pyupgrade: 3.6+ (#3805)

* pyupgrade: 3.6+

* tests: pyupgrade 3.6+

dvc/analytics.py

@@ -72,7 +72,7 @@ def send(path):
     url = "https://analytics.dvc.org"
     headers = {"content-type": "application/json"}
 
-    with open(path, "r") as fobj:
+    with open(path) as fobj:
         report = json.load(fobj)
 
     report.update(_runtime_info())
@@ -158,7 +158,7 @@ def _find_or_create_user_id():
     try:
         with Lock(lockfile):
             try:
-                with open(fname, "r") as fobj:
+                with open(fname) as fobj:
                     user_id = json.load(fobj)["user_id"]
 
             except (FileNotFoundError, ValueError, KeyError):
@@ -170,6 +170,4 @@ def _find_or_create_user_id():
             return user_id
 
     except LockError:
-        logger.debug(
-            "Failed to acquire '{lockfile}'".format(lockfile=lockfile)
-        )
+        logger.debug(f"Failed to acquire '{lockfile}'")

dvc/api.py

@@ -11,7 +11,7 @@ class UrlNotDvcRepoError(DvcException):
     """Thrown if the given URL is not a DVC repository."""
 
     def __init__(self, url):
-        super().__init__("'{}' is not a DVC repository.".format(url))
+        super().__init__(f"'{url}' is not a DVC repository.")
 
 
 def get_url(path, repo=None, rev=None, remote=None):

dvc/cache.py

@@ -40,7 +40,7 @@ def _make_remote_property(name):
     return cached_property(getter)
 
 
-class Cache(object):
+class Cache:
     """Class that manages cache locations of a DVC repo.
 
     Args:
@@ -101,7 +101,7 @@ class NamedCacheItem:
             self.children[checksum].update(child_item)
 
 
-class NamedCache(object):
+class NamedCache:
     def __init__(self):
         self._items = defaultdict(lambda: defaultdict(NamedCacheItem))
         self.external = defaultdict(set)

dvc/command/base.py

@@ -26,7 +26,7 @@ def append_doc_link(help_message, path):
     )
 
 
-class CmdBase(object):
+class CmdBase:
     def __init__(self, args):
         from dvc.repo import Repo
         from dvc.updater import Updater
@@ -43,7 +43,7 @@ class CmdBase(object):
         """Default targets for `dvc repro`."""
         from dvc.dvcfile import PIPELINE_FILE
 
-        msg = "assuming default target '{}'.".format(PIPELINE_FILE)
+        msg = f"assuming default target '{PIPELINE_FILE}'."
         logger.warning(msg)
         return [PIPELINE_FILE]
 

dvc/command/get_url.py

@@ -16,7 +16,7 @@ class CmdGetUrl(CmdBaseNoRepo):
             Repo.get_url(self.args.url, out=self.args.out)
             return 0
         except DvcException:
-            logger.exception("failed to get '{}'".format(self.args.url))
+            logger.exception(f"failed to get '{self.args.url}'")
             return 1
 
 

dvc/command/ls/__init__.py

@@ -38,7 +38,7 @@ class CmdList(CmdBaseNoRepo):
                 logger.info("\n".join(entries))
             return 0
         except DvcException:
-            logger.exception("failed to list '{}'".format(self.args.url))
+            logger.exception(f"failed to list '{self.args.url}'")
             return 1
 
 

dvc/command/ls/ls_colors.py

@@ -1,7 +1,7 @@
 import os
 
 
-class LsColors(object):
+class LsColors:
     default = "rs=0:di=01;34:ex=01;32"
 
     def __init__(self, lscolors=None):
@@ -45,4 +45,4 @@ class LsColors(object):
         if not val:
             return text
         rs = self._codes.get("rs", 0)
-        return "\033[{}m{}\033[{}m".format(val, text, rs)
+        return f"\033[{val}m{text}\033[{rs}m"

dvc/command/metrics.py

@@ -19,16 +19,16 @@ def show_metrics(
 
     for branch, val in metrics.items():
         if all_branches or all_tags or all_commits:
-            logger.info("{branch}:".format(branch=branch))
+            logger.info(f"{branch}:")
 
         for fname, metric in val.items():
             if not isinstance(metric, dict):
                 logger.info("\t{}: {}".format(fname, str(metric)))
                 continue
 
-            logger.info("\t{}:".format(fname))
+            logger.info(f"\t{fname}:")
             for key, value in flatten(format_dict(metric), ".").items():
-                logger.info("\t\t{}: {}".format(key, value))
+                logger.info(f"\t\t{key}: {value}")
 
     if missing:
         raise BadMetricError(missing)
@@ -68,7 +68,7 @@ class CmdMetricsAdd(CmdBase):
         try:
             self.repo.metrics.add(self.args.path)
         except DvcException:
-            msg = "failed to add metric file '{}'".format(self.args.path)
+            msg = f"failed to add metric file '{self.args.path}'"
             logger.exception(msg)
             return 1
 
@@ -80,7 +80,7 @@ class CmdMetricsRemove(CmdBase):
         try:
             self.repo.metrics.remove(self.args.path)
         except DvcException:
-            msg = "failed to remove metric file '{}'".format(self.args.path)
+            msg = f"failed to remove metric file '{self.args.path}'"
             logger.exception(msg)
             return 1
 

dvc/command/pipeline.py

@@ -164,7 +164,7 @@ class CmdPipelineShow(CmdBase):
                         self.args.locked,
                     )
             except DvcException:
-                msg = "failed to show pipeline for '{}'".format(target)
+                msg = f"failed to show pipeline for '{target}'"
                 logger.exception(msg)
                 return 1
         return 0

dvc/command/remote.py

@@ -18,17 +18,13 @@ class CmdRemote(CmdConfig):
 
     def _check_exists(self, conf):
         if self.args.name not in conf["remote"]:
-            raise ConfigError(
-                "remote '{}' doesn't exists.".format(self.args.name)
-            )
+            raise ConfigError(f"remote '{self.args.name}' doesn't exists.")
 
 
 class CmdRemoteAdd(CmdRemote):
     def run(self):
         if self.args.default:
-            logger.info(
-                "Setting '{}' as a default remote.".format(self.args.name)
-            )
+            logger.info(f"Setting '{self.args.name}' as a default remote.")
 
         with self.config.edit(self.args.level) as conf:
             if self.args.name in conf["remote"] and not self.args.force:

dvc/command/remove.py

@@ -34,7 +34,7 @@ class CmdRemove(CmdBase):
                 outs_only = self._is_outs_only(target)
                 self.repo.remove(target, outs_only=outs_only)
             except DvcException:
-                logger.exception("failed to remove '{}'".format(target))
+                logger.exception(f"failed to remove '{target}'")
                 return 1
         return 0
 

dvc/command/run.py

@@ -75,7 +75,7 @@ class CmdRun(CmdBase):
         if " " not in argument or '"' in argument:
             return argument
 
-        return '"{}"'.format(argument)
+        return f'"{argument}"'
 
 
 def add_parser(subparsers, parent_parser):

dvc/command/status.py

@@ -19,7 +19,7 @@ class CmdDataStatus(CmdDataBase):
         ind = indent * self.STATUS_INDENT
 
         if isinstance(status, str):
-            logger.info("{}{}".format(ind, status))
+            logger.info(f"{ind}{status}")
             return
 
         if isinstance(status, list):
@@ -33,7 +33,7 @@ class CmdDataStatus(CmdDataBase):
             if isinstance(value, str):
                 logger.info("{}{}{}".format(ind, self._normalize(value), key))
             elif value:
-                logger.info("{}{}:".format(ind, key))
+                logger.info(f"{ind}{key}:")
                 self._show(value, indent + 1)
 
     def run(self):

dvc/command/unprotect.py

@@ -13,7 +13,7 @@ class CmdUnprotect(CmdBase):
             try:
                 self.repo.unprotect(target)
             except DvcException:
-                msg = "failed to unprotect '{}'".format(target)
+                msg = f"failed to unprotect '{target}'"
                 logger.exception(msg)
                 return 1
         return 0

dvc/command/version.py

@@ -28,12 +28,12 @@ class CmdVersion(CmdBaseNoRepo):
         from dvc.repo import Repo
 
         info = [
-            "DVC version: {}".format(__version__),
-            "Python version: {}".format(platform.python_version()),
-            "Platform: {}".format(platform.platform()),
-            "Binary: {}".format(is_binary()),
-            "Package: {}".format(PKG),
-            "Supported remotes: {}".format(self.get_supported_remotes()),
+            f"DVC version: {__version__}",
+            f"Python version: {platform.python_version()}",
+            f"Platform: {platform.platform()}",
+            f"Binary: {is_binary()}",
+            f"Package: {PKG}",
+            f"Supported remotes: {self.get_supported_remotes()}",
         ]
 
         try:
@@ -51,7 +51,7 @@ class CmdVersion(CmdBaseNoRepo):
                 if psutil:
                     fs_type = self.get_fs_type(repo.cache.local.cache_dir)
                     info.append(
-                        "Filesystem type (cache directory): {}".format(fs_type)
+                        f"Filesystem type (cache directory): {fs_type}"
                     )
             else:
                 logger.warning(
@@ -72,7 +72,7 @@ class CmdVersion(CmdBaseNoRepo):
 
         if psutil:
             fs_root = self.get_fs_type(os.path.abspath(root_directory))
-            info.append("Filesystem type (workspace): {}".format(fs_root))
+            info.append(f"Filesystem type (workspace): {fs_root}")
 
         logger.info("\n".join(info))
         return 0
@@ -115,7 +115,7 @@ class CmdVersion(CmdBaseNoRepo):
                 os.unlink(dst)
             except DvcException:
                 status = "not supported"
-            cache.append("{name} - {status}".format(name=name, status=status))
+            cache.append(f"{name} - {status}")
         os.remove(src)
 
         return ", ".join(cache)

dvc/config.py

@@ -31,7 +31,7 @@ class ConfigError(DvcException):
     """DVC config exception."""
 
     def __init__(self, msg):
-        super().__init__("config file error: {}".format(msg))
+        super().__init__(f"config file error: {msg}")
 
 
 class NoRemoteError(ConfigError):
@@ -89,7 +89,7 @@ def ByUrl(mapping):
         if os.name == "nt" and len(parsed.scheme) == 1 and parsed.netloc == "":
             return schemas[""](data)
         if parsed.scheme not in schemas:
-            raise Invalid("Unsupported URL type {}://".format(parsed.scheme))
+            raise Invalid(f"Unsupported URL type {parsed.scheme}://")
 
         return schemas[parsed.scheme](data)
 
@@ -390,7 +390,7 @@ def _load_config(filename):
 
 
 def _save_config(filename, conf_dict):
-    logger.debug("Writing '{}'.".format(filename))
+    logger.debug(f"Writing '{filename}'.")
     os.makedirs(os.path.dirname(filename), exist_ok=True)
 
     config = configobj.ConfigObj(_pack_remotes(conf_dict))
@@ -417,7 +417,7 @@ def _pack_remotes(conf):
 
     # Transform remote.name -> 'remote "name"'
     for name, val in conf["remote"].items():
-        result['remote "{}"'.format(name)] = val
+        result[f'remote "{name}"'] = val
     result.pop("remote", None)
 
     return result

dvc/daemon.py

@@ -66,7 +66,7 @@ def _spawn_posix(cmd, env):
 
 
 def _spawn(cmd, env):
-    logger.debug("Trying to spawn '{}'".format(cmd))
+    logger.debug(f"Trying to spawn '{cmd}'")
 
     if os.name == "nt":
         _spawn_windows(cmd, env)
@@ -75,7 +75,7 @@ def _spawn(cmd, env):
     else:
         raise NotImplementedError
 
-    logger.debug("Spawned '{}'".format(cmd))
+    logger.debug(f"Spawned '{cmd}'")
 
 
 def daemon(args):

dvc/dagascii.py

@@ -37,7 +37,7 @@ def find_pager():
     if env_pager:
         return make_pager(env_pager)
 
-    if os.system("({}) 2>{}".format(DEFAULT_PAGER, os.devnull)) == 0:
+    if os.system(f"({DEFAULT_PAGER}) 2>{os.devnull}") == 0:
         return make_pager(DEFAULT_PAGER_FORMATTED)
 
     logger.warning(
@@ -49,7 +49,7 @@ def find_pager():
     return pydoc.plainpager
 
 
-class VertexViewer(object):
+class VertexViewer:
     """Class to define vertex box boundaries that will be accounted for during
     graph building by grandalf.
 
@@ -75,7 +75,7 @@ class VertexViewer(object):
         return self._w
 
 
-class AsciiCanvas(object):
+class AsciiCanvas:
     """Class for drawing in ASCII.
 
     Args:
@@ -145,21 +145,21 @@ class AsciiCanvas(object):
                 if dx == 0:
                     y = y0
                 else:
-                    y = y0 + int(round((x - x0) * dy / float((dx))))
+                    y = y0 + int(round((x - x0) * dy / float(dx)))
                 self.point(x, y, char)
         elif y0 < y1:
             for y in range(y0, y1 + 1):
                 if dy == 0:
                     x = x0
                 else:
-                    x = x0 + int(round((y - y0) * dx / float((dy))))
+                    x = x0 + int(round((y - y0) * dx / float(dy)))
                 self.point(x, y, char)
         else:
             for y in range(y1, y0 + 1):
                 if dy == 0:
                     x = x0
                 else:
-                    x = x1 + int(round((y - y1) * dx / float((dy))))
+                    x = x1 + int(round((y - y1) * dx / float(dy)))
                 self.point(x, y, char)
 
     def text(self, x, y, text):
@@ -213,7 +213,7 @@ def _build_sugiyama_layout(vertexes, edges):
     # Y
     #
 
-    vertexes = {v: Vertex(" {} ".format(v)) for v in vertexes}
+    vertexes = {v: Vertex(f" {v} ") for v in vertexes}
     # NOTE: reverting edges to correctly orientate the graph
     edges = [Edge(vertexes[e], vertexes[s]) for s, e in edges]
     vertexes = vertexes.values()

dvc/data_cloud.py

@@ -8,7 +8,7 @@ from dvc.remote import Remote
 logger = logging.getLogger(__name__)
 
 
-class DataCloud(object):
+class DataCloud:
     """Class that manages dvc remotes.
 
     Args:

dvc/dependency/base.py

@@ -3,24 +3,22 @@ from dvc.exceptions import DvcException
 
 class DependencyDoesNotExistError(DvcException):
     def __init__(self, path):
-        msg = "dependency '{}' does not exist".format(path)
+        msg = f"dependency '{path}' does not exist"
         super().__init__(msg)
 
 
 class DependencyIsNotFileOrDirError(DvcException):
     def __init__(self, path):
-        msg = "dependency '{}' is not a file or directory".format(path)
+        msg = f"dependency '{path}' is not a file or directory"
         super().__init__(msg)
 
 
 class DependencyIsStageFileError(DvcException):
     def __init__(self, path):
-        super().__init__(
-            "Stage file '{}' cannot be a dependency.".format(path)
-        )
+        super().__init__(f"Stage file '{path}' cannot be a dependency.")
 
 
-class BaseDependency(object):
+class BaseDependency:
     IS_DEPENDENCY = True
 
     DoesNotExistError = DependencyDoesNotExistError

dvc/dependency/param.py

@@ -91,7 +91,7 @@ class ParamsDependency(LocalDependency):
                 config = yaml.safe_load(fobj)
             except yaml.YAMLError as exc:
                 raise BadParamFileError(
-                    "Unable to read parameters from '{}'".format(self)
+                    f"Unable to read parameters from '{self}'"
                 ) from exc
 
         ret = {}

dvc/dvcfile.py

@@ -33,7 +33,7 @@ PIPELINE_LOCK = "dvc.lock"
 
 class LockfileCorruptedError(DvcException):
     def __init__(self, path):
-        super().__init__("Lockfile '{}' is corrupted.".format(path))
+        super().__init__(f"Lockfile '{path}' is corrupted.")
 
 
 def is_valid_filename(path):
@@ -80,7 +80,7 @@ class FileMixin:
         ) == os.path.abspath(other.path)
 
     def __str__(self):
-        return "{}: {}".format(self.__class__.__name__, self.relpath)
+        return f"{self.__class__.__name__}: {self.relpath}"
 
     @property
     def relpath(self):
@@ -192,7 +192,7 @@ class PipelineFile(FileMixin):
     def _dump_pipeline_file(self, stage):
         data = {}
         if self.exists():
-            with open(self.path, "r") as fd:
+            with open(self.path) as fd:
                 data = parse_stage_for_update(fd.read(), self.path)
         else:
             open(self.path, "w+").close()

dvc/exceptions.py

@@ -34,8 +34,7 @@ class OutputDuplicationError(DvcException):
             )
         else:
             msg = "output '{}' is already specified in stages:\n{}".format(
-                output,
-                "\n".join("\t- {}".format(s.addressing) for s in stages),
+                output, "\n".join(f"\t- {s.addressing}" for s in stages),
             )
         super().__init__(msg)
         self.stages = stages
@@ -102,7 +101,7 @@ class ArgumentDuplicationError(DvcException):
 
     def __init__(self, path):
         assert isinstance(path, str)
-        super().__init__("file '{}' is specified more than once.".format(path))
+        super().__init__(f"file '{path}' is specified more than once.")
 
 
 class MoveNotDataSourceError(DvcException):
@@ -158,7 +157,7 @@ class InitError(DvcException):
 class ReproductionError(DvcException):
     def __init__(self, dvc_file_name):
         self.path = dvc_file_name
-        super().__init__("failed to reproduce '{}'".format(dvc_file_name))
+        super().__init__(f"failed to reproduce '{dvc_file_name}'")
 
 
 class BadMetricError(DvcException):
@@ -166,7 +165,7 @@ class BadMetricError(DvcException):
         super().__init__(
             "the following metrics do not exist, "
             "are not metric files or are malformed: {paths}".format(
-                paths=", ".join("'{}'".format(path) for path in paths)
+                paths=", ".join(f"'{path}'" for path in paths)
             )
         )
 
@@ -204,7 +203,7 @@ class OverlappingOutputPathsError(DvcException):
 
 class CheckoutErrorSuggestGit(DvcException):
     def __init__(self, target):
-        super().__init__("Did you mean `git checkout {}`?".format(target))
+        super().__init__(f"Did you mean `git checkout {target}`?")
 
 
 class ETagMismatchError(DvcException):
@@ -218,9 +217,7 @@ class ETagMismatchError(DvcException):
 class FileMissingError(DvcException):
     def __init__(self, path):
         self.path = path
-        super().__init__(
-            "Can't find '{}' neither locally nor on remote".format(path)
-        )
+        super().__init__(f"Can't find '{path}' neither locally nor on remote")
 
 
 class DvcIgnoreInCollectedDirError(DvcException):
@@ -245,18 +242,14 @@ class DownloadError(DvcException):
     def __init__(self, amount):
         self.amount = amount
 
-        super().__init__(
-            "{amount} files failed to download".format(amount=amount)
-        )
+        super().__init__(f"{amount} files failed to download")
 
 
 class UploadError(DvcException):
     def __init__(self, amount):
         self.amount = amount
 
-        super().__init__(
-            "{amount} files failed to upload".format(amount=amount)
-        )
+        super().__init__(f"{amount} files failed to upload")
 
 
 class CheckoutError(DvcException):
@@ -278,7 +271,7 @@ class CollectCacheError(DvcException):
 class NoRemoteInExternalRepoError(DvcException):
     def __init__(self, url):
         super().__init__(
-            "No DVC remote is specified in target repository '{}'.".format(url)
+            f"No DVC remote is specified in target repository '{url}'."
         )
 
 
@@ -293,7 +286,7 @@ class NoOutputInExternalRepoError(DvcException):
 
 class HTTPError(DvcException):
     def __init__(self, code, reason):
-        super().__init__("'{} {}'".format(code, reason))
+        super().__init__(f"'{code} {reason}'")
 
 
 class PathMissingError(DvcException):

dvc/ignore.py

@@ -11,7 +11,7 @@ from dvc.utils import relpath
 logger = logging.getLogger(__name__)
 
 
-class DvcIgnore(object):
+class DvcIgnore:
     DVCIGNORE_FILE = ".dvcignore"
 
     def __call__(self, root, dirs, files):
@@ -83,7 +83,7 @@ class DvcIgnoreRepo(DvcIgnore):
         return dirs, files
 
 
-class DvcIgnoreFilter(object):
+class DvcIgnoreFilter:
     def __init__(self, tree):
         self.tree = tree
         self.ignores = {

dvc/lock.py

@@ -25,7 +25,7 @@ class LockError(DvcException):
     """Thrown when unable to acquire the lock for DVC repo."""
 
 
-class Lock(object):
+class Lock:
     """Class for DVC repo lock.
 
     Uses zc.lockfile as backend.

dvc/output/base.py

@@ -19,28 +19,28 @@ logger = logging.getLogger(__name__)
 
 class OutputDoesNotExistError(DvcException):
     def __init__(self, path):
-        msg = "output '{}' does not exist".format(path)
+        msg = f"output '{path}' does not exist"
         super().__init__(msg)
 
 
 class OutputIsNotFileOrDirError(DvcException):
     def __init__(self, path):
-        msg = "output '{}' is not a file or directory".format(path)
+        msg = f"output '{path}' is not a file or directory"
         super().__init__(msg)
 
 
 class OutputAlreadyTrackedError(DvcException):
     def __init__(self, path):
-        msg = "output '{}' is already tracked by SCM (e.g. Git)".format(path)
+        msg = f"output '{path}' is already tracked by SCM (e.g. Git)"
         super().__init__(msg)
 
 
 class OutputIsStageFileError(DvcException):
     def __init__(self, path):
-        super().__init__("Stage file '{}' cannot be an output.".format(path))
+        super().__init__(f"Stage file '{path}' cannot be an output.")
 
 
-class BaseOutput(object):
+class BaseOutput:
     IS_DEPENDENCY = False
 
     REMOTE = BaseRemote
@@ -228,7 +228,7 @@ class BaseOutput(object):
             raise self.IsNotFileOrDirError(self)
 
         if self.is_empty:
-            logger.warning("'{}' is empty.".format(self))
+            logger.warning(f"'{self}' is empty.")
 
         self.ignore()
 
@@ -247,9 +247,7 @@ class BaseOutput(object):
         assert not self.IS_DEPENDENCY
 
         if not self.changed():
-            logger.info(
-                "Output '{}' didn't change. Skipping saving.".format(self)
-            )
+            logger.info(f"Output '{self}' didn't change. Skipping saving.")
             return
 
         self.info = self.save_info()
@@ -280,9 +278,7 @@ class BaseOutput(object):
         return ret
 
     def verify_metric(self):
-        raise DvcException(
-            "verify metric is not supported for {}".format(self.scheme)
-        )
+        raise DvcException(f"verify metric is not supported for {self.scheme}")
 
     def download(self, to):
         self.remote.download(self.path_info, to.path_info)
@@ -376,7 +372,7 @@ class BaseOutput(object):
                     show_checksums=False,
                 )
             except DvcException:
-                logger.debug("failed to pull cache for '{}'".format(self))
+                logger.debug(f"failed to pull cache for '{self}'")
 
         if self.cache.changed_cache_file(self.checksum):
             msg = (

dvc/path_info.py

@@ -8,7 +8,7 @@ from funcy import cached_property
 from dvc.utils import relpath
 
 
-class _BasePath(object):
+class _BasePath:
     def overlaps(self, other):
         if isinstance(other, (str, bytes)):
             other = self.__class__(other)
@@ -87,7 +87,7 @@ class _URLPathInfo(PosixPathInfo):
     __unicode__ = __str__
 
 
-class _URLPathParents(object):
+class _URLPathParents:
     def __init__(self, src):
         self.src = src
         self._parents = self.src._path.parents
@@ -99,7 +99,7 @@ class _URLPathParents(object):
         return self.src.replace(path=self._parents[idx])
 
     def __repr__(self):
-        return "<{}.parents>".format(self.src)
+        return f"<{self.src}.parents>"
 
 
 class URLInfo(_BasePath):
@@ -119,7 +119,7 @@ class URLInfo(_BasePath):
         assert bool(host) ^ bool(netloc)
 
         if netloc is not None:
-            return cls("{}://{}{}".format(scheme, netloc, path))
+            return cls(f"{scheme}://{netloc}{path}")
 
         obj = cls.__new__(cls)
         obj._fill_parts(scheme, host, user, port, path)
@@ -153,7 +153,7 @@ class URLInfo(_BasePath):
 
     @cached_property
     def url(self):
-        return "{}://{}{}".format(self.scheme, self.netloc, self._spath)
+        return f"{self.scheme}://{self.netloc}{self._spath}"
 
     def __str__(self):
         return self.url
@@ -215,10 +215,10 @@ class URLInfo(_BasePath):
         if isinstance(other, (str, bytes)):
             other = self.__class__(other)
         if self.__class__ != other.__class__:
-            msg = "'{}' has incompatible class with '{}'".format(self, other)
+            msg = f"'{self}' has incompatible class with '{other}'"
             raise ValueError(msg)
         if self._base_parts != other._base_parts:
-            msg = "'{}' does not start with '{}'".format(self, other)
+            msg = f"'{self}' does not start with '{other}'"
             raise ValueError(msg)
         return self._path.relative_to(other._path)
 

dvc/prompt.py

@@ -38,7 +38,7 @@ def confirm(statement):
     Returns:
         bool: whether or not specified statement was confirmed.
     """
-    prompt = "{statement} [y/n]".format(statement=statement)
+    prompt = f"{statement} [y/n]"
     answer = _ask(prompt, limited_to=["yes", "no", "y", "n"])
     return answer and answer.startswith("y")
 
@@ -52,5 +52,5 @@ def password(statement):
     Returns:
         str: password entered by the user.
     """
-    logger.info("{statement}: ".format(statement=statement))
+    logger.info(f"{statement}: ")
     return getpass("")

dvc/remote/azure.py

@@ -67,12 +67,12 @@ class AzureRemote(BaseRemote):
         from azure.storage.blob import BlockBlobService
         from azure.common import AzureMissingResourceHttpError
 
-        logger.debug("URL {}".format(self.path_info))
-        logger.debug("Connection string {}".format(self.connection_string))
+        logger.debug(f"URL {self.path_info}")
+        logger.debug(f"Connection string {self.connection_string}")
         blob_service = BlockBlobService(
             connection_string=self.connection_string
         )
-        logger.debug("Container name {}".format(self.path_info.bucket))
+        logger.debug(f"Container name {self.path_info.bucket}")
         try:  # verify that container exists
             blob_service.list_blobs(
                 self.path_info.bucket, delimiter="/", num_results=1
@@ -85,7 +85,7 @@ class AzureRemote(BaseRemote):
         if path_info.scheme != self.scheme:
             raise NotImplementedError
 
-        logger.debug("Removing {}".format(path_info))
+        logger.debug(f"Removing {path_info}")
         self.blob_service.delete_blob(path_info.bucket, path_info.path)
 
     def _list_paths(self, bucket, prefix, progress_callback=None):

dvc/remote/base.py

@@ -57,7 +57,7 @@ class RemoteCmdError(DvcException):
 
 class RemoteActionNotImplemented(DvcException):
     def __init__(self, action, scheme):
-        m = "{} is not supported for {} remotes".format(action, scheme)
+        m = f"{action} is not supported for {scheme} remotes"
         super().__init__(m)
 
 
@@ -68,7 +68,7 @@ class RemoteMissingDepsError(DvcException):
 class DirCacheError(DvcException):
     def __init__(self, checksum):
         super().__init__(
-            "Failed to load dir cache for hash value: '{}'.".format(checksum)
+            f"Failed to load dir cache for hash value: '{checksum}'."
         )
 
 
@@ -82,7 +82,7 @@ def index_locked(f):
     return wrapper
 
 
-class BaseRemote(object):
+class BaseRemote:
     scheme = "base"
     path_cls = URLInfo
     REQUIRES = {}
@@ -151,7 +151,7 @@ class BaseRemote(object):
         if not missing:
             return
 
-        url = config.get("url", "{}://".format(self.scheme))
+        url = config.get("url", f"{self.scheme}://")
         msg = (
             "URL '{}' is supported but requires these missing "
             "dependencies: {}. If you have installed dvc using pip, "
@@ -418,10 +418,10 @@ class BaseRemote(object):
         if self.cache_type_confirmed:
             return
 
-        is_link = getattr(self, "is_{}".format(link_type), None)
+        is_link = getattr(self, f"is_{link_type}", None)
         if is_link and not is_link(path_info):
             self.remove(path_info)
-            raise DvcException("failed to verify {}".format(link_type))
+            raise DvcException(f"failed to verify {link_type}")
 
         self.cache_type_confirmed = True
 
@@ -444,7 +444,7 @@ class BaseRemote(object):
 
     def _do_link(self, from_info, to_info, link_method):
         if self.exists(to_info):
-            raise DvcException("Link '{}' already exists!".format(to_info))
+            raise DvcException(f"Link '{to_info}' already exists!")
 
         link_method(from_info, to_info)
 
@@ -544,8 +544,7 @@ class BaseRemote(object):
     def save(self, path_info, checksum_info, save_link=True):
         if path_info.scheme != self.scheme:
             raise RemoteActionNotImplemented(
-                "save {} -> {}".format(path_info.scheme, self.scheme),
-                self.scheme,
+                f"save {path_info.scheme} -> {self.scheme}", self.scheme,
             )
 
         checksum = checksum_info[self.PARAM_CHECKSUM]
@@ -712,7 +711,7 @@ class BaseRemote(object):
         parts = self.path_cls(path).parts[-2:]
 
         if not (len(parts) == 2 and parts[0] and len(parts[0]) == 2):
-            raise ValueError("Bad cache file path '{}'".format(path))
+            raise ValueError(f"Bad cache file path '{path}'")
 
         return "".join(parts)
 
@@ -991,7 +990,7 @@ class BaseRemote(object):
 
         with Tqdm(
             desc="Estimating size of "
-            + ("cache in '{}'".format(name) if name else "remote cache"),
+            + (f"cache in '{name}'" if name else "remote cache"),
             unit="file",
         ) as pbar:
 
@@ -1010,7 +1009,7 @@ class BaseRemote(object):
                 remote_size = total_prefixes * len(remote_checksums)
             else:
                 remote_size = total_prefixes
-            logger.debug("Estimated remote size: {} files".format(remote_size))
+            logger.debug(f"Estimated remote size: {remote_size} files")
         return remote_size, remote_checksums
 
     def _cache_checksums_traverse(
@@ -1043,7 +1042,7 @@ class BaseRemote(object):
         else:
             yield from remote_checksums
             initial = len(remote_checksums)
-            traverse_prefixes = ["{:02x}".format(i) for i in range(1, 256)]
+            traverse_prefixes = [f"{i:02x}" for i in range(1, 256)]
             if self.TRAVERSE_PREFIX_LEN > 2:
                 traverse_prefixes += [
                     "{0:0{1}x}".format(i, self.TRAVERSE_PREFIX_LEN)
@@ -1051,7 +1050,7 @@ class BaseRemote(object):
                 ]
         with Tqdm(
             desc="Querying "
-            + ("cache in '{}'".format(name) if name else "remote cache"),
+            + (f"cache in '{name}'" if name else "remote cache"),
             total=remote_size,
             initial=initial,
             unit="file",

dvc/remote/gdrive.py

@@ -22,10 +22,8 @@ FOLDER_MIME_TYPE = "application/vnd.google-apps.folder"
 
 class GDrivePathNotFound(DvcException):
     def __init__(self, path_info, hint):
-        hint = "" if hint is None else " {}".format(hint)
-        super().__init__(
-            "GDrive path '{}' not found.{}".format(path_info, hint)
-        )
+        hint = "" if hint is None else f" {hint}"
+        super().__init__(f"GDrive path '{path_info}' not found.{hint}")
 
 
 class GDriveAuthError(DvcException):
@@ -62,7 +60,7 @@ def _gdrive_retry(func):
                 "rateLimitExceeded",
             ]
         if result:
-            logger.debug("Retrying GDrive API call, error: {}.".format(exc))
+            logger.debug(f"Retrying GDrive API call, error: {exc}.")
 
         return result
 
@@ -465,7 +463,7 @@ class GDriveRemote(BaseRemote):
             return None
         query = "trashed=false and ({})".format(
             " or ".join(
-                "'{}' in parents".format(parent_id) for parent_id in parent_ids
+                f"'{parent_id}' in parents" for parent_id in parent_ids
             )
         )
         query += " and title='{}'".format(title.replace("'", "\\'"))
@@ -542,9 +540,9 @@ class GDriveRemote(BaseRemote):
         else:
             dir_ids = self._ids_cache["ids"]
         parents_query = " or ".join(
-            "'{}' in parents".format(dir_id) for dir_id in dir_ids
+            f"'{dir_id}' in parents" for dir_id in dir_ids
         )
-        query = "({}) and trashed=false".format(parents_query)
+        query = f"({parents_query}) and trashed=false"
 
         for item in self._gdrive_list(query):
             if progress_callback:

dvc/remote/gs.py

@@ -1,4 +1,3 @@
-import io
 import logging
 import os.path
 import posixpath
@@ -55,7 +54,7 @@ def _upload_to_bucket(
     no_progress_bar=False,
 ):
     blob = bucket.blob(to_info.path, chunk_size=chunk_size)
-    with io.open(from_file, mode="rb") as fobj:
+    with open(from_file, mode="rb") as fobj:
         with Tqdm.wrapattr(
             fobj,
             "read",
@@ -110,7 +109,7 @@ class GSRemote(BaseRemote):
         from_bucket = self.gs.bucket(from_info.bucket)
         blob = from_bucket.get_blob(from_info.path)
         if not blob:
-            msg = "'{}' doesn't exist in the cloud".format(from_info.path)
+            msg = f"'{from_info.path}' doesn't exist in the cloud"
             raise DvcException(msg)
 
         to_bucket = self.gs.bucket(to_info.bucket)
@@ -120,7 +119,7 @@ class GSRemote(BaseRemote):
         if path_info.scheme != "gs":
             raise NotImplementedError
 
-        logger.debug("Removing gs://{}".format(path_info))
+        logger.debug(f"Removing gs://{path_info}")
         blob = self.gs.bucket(path_info.bucket).get_blob(path_info.path)
         if not blob:
             return
@@ -193,7 +192,7 @@ class GSRemote(BaseRemote):
     def _download(self, from_info, to_file, name=None, no_progress_bar=False):
         bucket = self.gs.bucket(from_info.bucket)
         blob = bucket.get_blob(from_info.path)
-        with io.open(to_file, mode="wb") as fobj:
+        with open(to_file, mode="wb") as fobj:
             with Tqdm.wrapattr(
                 fobj,
                 "write",

dvc/remote/hdfs.py

@@ -55,7 +55,7 @@ class HDFSRemote(BaseRemote):
     def hadoop_fs(self, cmd, user=None):
         cmd = "hadoop fs -" + cmd
         if user:
-            cmd = "HADOOP_USER_NAME={} ".format(user) + cmd
+            cmd = f"HADOOP_USER_NAME={user} " + cmd
 
         # NOTE: close_fds doesn't work with redirected stdin/stdout/stderr.
         # See https://github.com/iterative/dvc/issues/1197.
@@ -87,7 +87,7 @@ class HDFSRemote(BaseRemote):
         # NOTE: pyarrow doesn't support checksum, so we need to use hadoop
         regex = r".*\t.*\t(?P<checksum>.*)"
         stdout = self.hadoop_fs(
-            "checksum {}".format(path_info.path), user=path_info.user
+            f"checksum {path_info.path}", user=path_info.user
         )
         return self._group(regex, stdout, "checksum")
 
@@ -112,7 +112,7 @@ class HDFSRemote(BaseRemote):
             raise NotImplementedError
 
         if self.exists(path_info):
-            logger.debug("Removing {}".format(path_info.path))
+            logger.debug(f"Removing {path_info.path}")
             with self.hdfs(path_info) as hdfs:
                 hdfs.rm(path_info.path)
 
@@ -147,7 +147,7 @@ class HDFSRemote(BaseRemote):
                     yield fd
                 else:
                     yield io.TextIOWrapper(fd, encoding=encoding)
-        except IOError as e:
+        except OSError as e:
             # Empty .errno and not specific enough error class in pyarrow,
             # see https://issues.apache.org/jira/browse/ARROW-6248
             if "file does not exist" in str(e):
@@ -175,7 +175,7 @@ class HDFSRemote(BaseRemote):
                             if progress_callback:
                                 progress_callback()
                             yield urlparse(entry["name"]).path
-                except IOError as e:
+                except OSError as e:
                     # When searching for a specific prefix pyarrow raises an
                     # exception if the specified cache dir does not exist
                     if not prefix:

dvc/remote/http.py

@@ -185,7 +185,7 @@ class HTTPRemote(BaseRemote):
             return res
 
         except requests.exceptions.RequestException:
-            raise DvcException("could not perform a {} request".format(method))
+            raise DvcException(f"could not perform a {method} request")
 
     def gc(self):
         raise NotImplementedError

dvc/remote/index.py

@@ -69,9 +69,7 @@ class RemoteIndex:
     INDEX_TABLE_LAYOUT = "checksum TEXT PRIMARY KEY, " "dir INTEGER NOT NULL"
 
     def __init__(self, repo, name, dir_suffix=".dir"):
-        self.path = os.path.join(
-            repo.index_dir, "{}{}".format(name, self.INDEX_SUFFIX)
-        )
+        self.path = os.path.join(repo.index_dir, f"{name}{self.INDEX_SUFFIX}")
 
         self.dir_suffix = dir_suffix
         self.database = None
@@ -80,7 +78,7 @@ class RemoteIndex:
         self.lock = threading.Lock()
 
     def __iter__(self):
-        cmd = "SELECT checksum FROM {}".format(self.INDEX_TABLE)
+        cmd = f"SELECT checksum FROM {self.INDEX_TABLE}"
         for (checksum,) in self._execute(cmd):
             yield checksum
 
@@ -105,7 +103,7 @@ class RemoteIndex:
 
     def dir_checksums(self):
         """Iterate over .dir checksums stored in the index."""
-        cmd = "SELECT checksum FROM {} WHERE dir = 1".format(self.INDEX_TABLE)
+        cmd = f"SELECT checksum FROM {self.INDEX_TABLE} WHERE dir = 1"
         for (checksum,) in self._execute(cmd):
             yield checksum
 
@@ -184,7 +182,7 @@ class RemoteIndex:
 
         Changes to the index will not committed until dump() is called.
         """
-        cmd = "DELETE FROM {}".format(self.INDEX_TABLE)
+        cmd = f"DELETE FROM {self.INDEX_TABLE}"
         self._execute(cmd)
 
     def update(self, dir_checksums, file_checksums):

dvc/remote/local.py

@@ -301,9 +301,7 @@ class LocalRemote(BaseRemote):
         {dir_checksum: set(file_checksum, ...)} which can be used to map
         a .dir file to its file contents.
         """
-        logger.debug(
-            "Preparing to collect status from {}".format(remote.path_info)
-        )
+        logger.debug(f"Preparing to collect status from {remote.path_info}")
         md5s = set(named_cache.scheme_keys(self.scheme))
 
         logger.debug("Collecting information from local cache...")
@@ -549,9 +547,7 @@ class LocalRemote(BaseRemote):
                     "failed to upload full contents of '{}', "
                     "aborting .dir file upload".format(name)
                 )
-                logger.error(
-                    "failed to upload '{}' to '{}'".format(from_info, to_info)
-                )
+                logger.error(f"failed to upload '{from_info}' to '{to_info}'")
                 return 1
         return func(from_info, to_info, name)
 
@@ -595,7 +591,7 @@ class LocalRemote(BaseRemote):
 
     def _unprotect_file(self, path):
         if System.is_symlink(path) or System.is_hardlink(path):
-            logger.debug("Unprotecting '{}'".format(path))
+            logger.debug(f"Unprotecting '{path}'")
             tmp = os.path.join(os.path.dirname(path), "." + uuid())
 
             # The operations order is important here - if some application
@@ -624,9 +620,7 @@ class LocalRemote(BaseRemote):
     def unprotect(self, path_info):
         path = path_info.fspath
         if not os.path.exists(path):
-            raise DvcException(
-                "can't unprotect non-existing data '{}'".format(path)
-            )
+            raise DvcException(f"can't unprotect non-existing data '{path}'")
 
         if os.path.isdir(path):
             self._unprotect_dir(path)
@@ -678,7 +672,7 @@ class LocalRemote(BaseRemote):
             dir_info = self.get_dir_cache(checksum)
             self._create_unpacked_dir(checksum, dir_info, unpacked_dir_info)
         except DvcException:
-            logger.warning("Could not create '{}'".format(unpacked_dir_info))
+            logger.warning(f"Could not create '{unpacked_dir_info}'")
 
             self.remove(unpacked_dir_info)
 

dvc/remote/oss.py

@@ -64,9 +64,9 @@ class OSSRemote(BaseRemote):
     def oss_service(self):
         import oss2
 
-        logger.debug("URL: {}".format(self.path_info))
-        logger.debug("key id: {}".format(self.key_id))
-        logger.debug("key secret: {}".format(self.key_secret))
+        logger.debug(f"URL: {self.path_info}")
+        logger.debug(f"key id: {self.key_id}")
+        logger.debug(f"key secret: {self.key_secret}")
 
         auth = oss2.Auth(self.key_id, self.key_secret)
         bucket = oss2.Bucket(auth, self.endpoint, self.path_info.bucket)
@@ -87,7 +87,7 @@ class OSSRemote(BaseRemote):
         if path_info.scheme != self.scheme:
             raise NotImplementedError
 
-        logger.debug("Removing oss://{}".format(path_info))
+        logger.debug(f"Removing oss://{path_info}")
         self.oss_service.delete_object(path_info.path)
 
     def _list_paths(self, prefix, progress_callback=None):

dvc/remote/pool.py

@@ -30,7 +30,7 @@ def close_pools():
     get_pool.memory.clear()
 
 
-class Pool(object):
+class Pool:
     def __init__(self, conn_func, *conn_args, **conn_kwargs):
         self._conn_func = conn_func
         self._conn_args = conn_args

dvc/remote/s3.py

@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-
 import logging
 import os
 import posixpath
@@ -88,9 +86,7 @@ class S3Remote(BaseRemote):
         try:
             obj = s3.head_object(Bucket=bucket, Key=path, *args, **kwargs)
         except Exception as exc:
-            raise DvcException(
-                "s3://{}/{} does not exist".format(bucket, path)
-            ) from exc
+            raise DvcException(f"s3://{bucket}/{path} does not exist") from exc
         return obj
 
     @classmethod
@@ -113,7 +109,7 @@ class S3Remote(BaseRemote):
             if lastbyte > size:
                 lastbyte = size - 1
 
-            srange = "bytes={}-{}".format(byte_position, lastbyte)
+            srange = f"bytes={byte_position}-{lastbyte}"
 
             part = s3.upload_part_copy(
                 Bucket=to_info.bucket,
@@ -191,7 +187,7 @@ class S3Remote(BaseRemote):
         if path_info.scheme != "s3":
             raise NotImplementedError
 
-        logger.debug("Removing {}".format(path_info))
+        logger.debug(f"Removing {path_info}")
         self.s3.delete_object(Bucket=path_info.bucket, Key=path_info.path)
 
     def _list_objects(

dvc/remote/ssh/__init__.py

@@ -290,7 +290,7 @@ class SSHRemote(BaseRemote):
                 try:
                     channel.stat(path)
                     ret.append(True)
-                except IOError as exc:
+                except OSError as exc:
                     if exc.errno != errno.ENOENT:
                         raise
                     ret.append(False)

dvc/remote/ssh/connection.py

@@ -25,9 +25,9 @@ def sizeof_fmt(num, suffix="B"):
     """ Convert number of bytes to human-readable string """
     for unit in ["", "K", "M", "G", "T", "P", "E", "Z"]:
         if abs(num) < 1024.0:
-            return "%3.1f%s%s" % (num, unit, suffix)
+            return f"{num:3.1f}{unit}{suffix}"
         num /= 1024.0
-    return "%.1f%s%s" % (num, "Y", suffix)
+    return "{:.1f}{}{}".format(num, "Y", suffix)
 
 
 class SSHConnection:
@@ -100,7 +100,7 @@ class SSHConnection:
 
         if stat.S_ISREG(st_mode) or stat.S_ISLNK(st_mode):
             raise DvcException(
-                "a file with the same name '{}' already exists".format(path)
+                f"a file with the same name '{path}' already exists"
             )
 
         head, tail = posixpath.split(path)
@@ -111,12 +111,12 @@ class SSHConnection:
         if tail:
             try:
                 self.sftp.mkdir(path)
-            except IOError as exc:
+            except OSError as exc:
                 # Since paramiko errors are very vague we need to recheck
                 # whether it's because path already exists or something else
                 if exc.errno == errno.EACCES or not self.exists(path):
                     raise DvcException(
-                        "unable to create remote directory '{}'".format(path)
+                        f"unable to create remote directory '{path}'"
                     ) from exc
 
     def walk(self, directory, topdown=True):
@@ -126,7 +126,7 @@ class SSHConnection:
         # [1] https://github.com/python/cpython/blob/master/Lib/os.py
         try:
             dir_entries = self.sftp.listdir_attr(directory)
-        except IOError as exc:
+        except OSError as exc:
             raise DvcException(
                 "couldn't get the '{}' remote directory files list".format(
                     directory
@@ -292,14 +292,14 @@ class SSHConnection:
             md5 = self.execute("md5 " + path).split()[-1]
         else:
             raise DvcException(
-                "'{}' is not supported as a SSH remote".format(self.uname)
+                f"'{self.uname}' is not supported as a SSH remote"
             )
 
         assert len(md5) == 32
         return md5
 
     def copy(self, src, dest):
-        self.execute("cp {} {}".format(src, dest))
+        self.execute(f"cp {src} {dest}")
 
     def open_max_sftp_channels(self):
         # If there are more than 1 it means we've already opened max amount
@@ -321,14 +321,12 @@ class SSHConnection:
 
     def reflink(self, src, dest):
         if self.uname == "Linux":
-            return self.execute("cp --reflink {} {}".format(src, dest))
+            return self.execute(f"cp --reflink {src} {dest}")
 
         if self.uname == "Darwin":
-            return self.execute("cp -c {} {}".format(src, dest))
+            return self.execute(f"cp -c {src} {dest}")
 
-        raise DvcException(
-            "'{}' is not supported as a SSH remote".format(self.uname)
-        )
+        raise DvcException(f"'{self.uname}' is not supported as a SSH remote")
 
     def hardlink(self, src, dest):
-        self.execute("ln {} {}".format(src, dest))
+        self.execute(f"ln {src} {dest}")

dvc/repo/__init__.py

@@ -33,7 +33,7 @@ def locked(f):
     return wrapper
 
 
-class Repo(object):
+class Repo:
     DVC_DIR = ".dvc"
 
     from dvc.repo.destroy import destroy
@@ -123,14 +123,14 @@ class Repo(object):
         self._reset()
 
     def __repr__(self):
-        return "{}: '{}'".format(self.__class__.__name__, self.root_dir)
+        return f"{self.__class__.__name__}: '{self.root_dir}'"
 
     @classmethod
     def find_root(cls, root=None):
         root_dir = os.path.realpath(root or os.curdir)
 
         if not os.path.isdir(root_dir):
-            raise NotDvcRepoError("directory '{}' does not exist".format(root))
+            raise NotDvcRepoError(f"directory '{root}' does not exist")
 
         while True:
             dvc_dir = os.path.join(root_dir, cls.DVC_DIR)
@@ -281,7 +281,7 @@ class Repo(object):
                 for target in targets
             )
 
-            suffix = "({})".format(branch) if branch else ""
+            suffix = f"({branch})" if branch else ""
             for stage, filter_info in pairs:
                 used_cache = stage.get_used_cache(
                     remote=remote,

dvc/repo/gc.py

@@ -11,7 +11,7 @@ logger = logging.getLogger(__name__)
 def _do_gc(typ, func, clist, jobs=None):
     removed = func(clist, jobs=jobs)
     if not removed:
-        logger.info("No unused '{}' cache to remove.".format(typ))
+        logger.info(f"No unused '{typ}' cache to remove.")
 
 
 def _raise_error_if_all_disabled(**kwargs):

dvc/repo/metrics/__init__.py

@@ -1,4 +1,4 @@
-class Metrics(object):
+class Metrics:
     def __init__(self, repo):
         self.repo = repo
 

dvc/repo/params/__init__.py

@@ -1,4 +1,4 @@
-class Params(object):
+class Params:
     def __init__(self, repo):
         self.repo = repo
 

dvc/repo/plots/__init__.py

@@ -148,7 +148,7 @@ def plot(
 
 
 def _parse_template(template_path, priority_datafile):
-    with open(template_path, "r") as fobj:
+    with open(template_path) as fobj:
         tempalte_content = fobj.read()
 
     template_datafiles = Template.parse_data_anchors(tempalte_content)

dvc/repo/plots/data.py

@@ -45,14 +45,12 @@ class NoMetricOnRevisionError(DvcException):
     def __init__(self, path, revision):
         self.path = path
         self.revision = revision
-        super().__init__(
-            "Could not find '{}' on revision '{}'".format(path, revision)
-        )
+        super().__init__(f"Could not find '{path}' on revision '{revision}'")
 
 
 class NoMetricInHistoryError(DvcException):
     def __init__(self, path):
-        super().__init__("Could not find '{}'.".format(path))
+        super().__init__(f"Could not find '{path}'.")
 
 
 def plot_data(filename, revision, content):
@@ -194,13 +192,13 @@ class JSONPlotData(PlotData):
         return json.loads(self.content, object_pairs_hook=OrderedDict)
 
     def _processors(self):
-        parent_processors = super(JSONPlotData, self)._processors()
+        parent_processors = super()._processors()
         return [_apply_path, _find_data] + parent_processors
 
 
 class CSVPlotData(PlotData):
     def __init__(self, filename, revision, content, delimiter=","):
-        super(CSVPlotData, self).__init__(filename, revision, content)
+        super().__init__(filename, revision, content)
         self.delimiter = delimiter
 
     def raw(self, csv_header=True, **kwargs):
@@ -277,7 +275,7 @@ def _load_from_revisions(repo, datafile, revisions):
         except PlotMetricTypeError:
             raise
         except (yaml.error.YAMLError, json.decoder.JSONDecodeError, csv.Error):
-            logger.error("Failed to parse '{}' at '{}'.".format(datafile, rev))
+            logger.error(f"Failed to parse '{datafile}' at '{rev}'.")
             raise
 
     if not data and exceptions:

dvc/repo/plots/template.py

@@ -13,7 +13,7 @@ logger = logging.getLogger(__name__)
 
 class TemplateNotFoundError(DvcException):
     def __init__(self, path):
-        super().__init__("Template '{}' not found.".format(path))
+        super().__init__(f"Template '{path}' not found.")
 
 
 class NoDataForTemplateError(DvcException):
@@ -26,7 +26,7 @@ class NoDataForTemplateError(DvcException):
 class NoFieldInDataError(DvcException):
     def __init__(self, field_name):
         super().__init__(
-            "Field '{}' does not exist in provided data.".format(field_name)
+            f"Field '{field_name}' does not exist in provided data."
         )
 
 
@@ -94,7 +94,7 @@ class Template:
         x_title=None,
         y_title=None,
     ):
-        with open(template_path, "r") as fobj:
+        with open(template_path) as fobj:
             result_content = fobj.read()
 
         if x_field:

dvc/repo/tree.py

@@ -29,7 +29,7 @@ class DvcTree(BaseTree):
             raise FileNotFoundError from exc
 
         if len(outs) != 1 or outs[0].is_dir_checksum:
-            raise IOError(errno.EISDIR)
+            raise OSError(errno.EISDIR)
 
         out = outs[0]
         # temporary hack to make cache use WorkingTree and not GitTree, because

dvc/rwlock.py

@@ -38,7 +38,7 @@ class RWLockFileFormatError(DvcException):
 def _edit_rwlock(lock_dir):
     path = os.path.join(lock_dir, "rwlock")
     try:
-        with open(path, "r") as fobj:
+        with open(path) as fobj:
             lock = SCHEMA(json.load(fobj))
     except FileNotFoundError:
         lock = SCHEMA({})

dvc/scm/base.py

@@ -17,7 +17,7 @@ class FileNotInRepoError(SCMError):
 
 class CloneError(SCMError):
     def __init__(self, url, path):
-        super().__init__("Failed to clone repo '{}' to '{}'".format(url, path))
+        super().__init__(f"Failed to clone repo '{url}' to '{path}'")
 
 
 class RevError(SCMError):
@@ -34,7 +34,7 @@ class NoSCMError(SCMError):
         super().__init__(msg)
 
 
-class Base(object):
+class Base:
     """Base class for source control management driver implementations."""
 
     def __init__(self, root_dir=os.curdir):

dvc/scm/git/__init__.py

@@ -30,7 +30,7 @@ class TqdmGit(Tqdm):
         if op_code:
             message = (op_code + " | " + message) if message else op_code
         if message:
-            self.postfix["info"] = " {} | ".format(message)
+            self.postfix["info"] = f" {message} | "
         self.update_to(cur_count, max_count)
 
     @staticmethod
@@ -211,7 +211,7 @@ class Git(Base):
                 fobj.seek(fobj.tell() - 1, os.SEEK_SET)
                 last = fobj.read(1)
                 prefix = "" if last == "\n" else "\n"
-            fobj.write("{}{}\n".format(prefix, entry))
+            fobj.write(f"{prefix}{entry}\n")
 
     def ignore_remove(self, path):
         entry, gitignore = self._get_gitignore(path)
@@ -219,7 +219,7 @@ class Git(Base):
         if not os.path.exists(gitignore):
             return
 
-        with open(gitignore, "r") as fobj:
+        with open(gitignore) as fobj:
             lines = fobj.readlines()
 
         filtered = list(filter(lambda x: x.strip() != entry.strip(), lines))
@@ -257,13 +257,13 @@ class Git(Base):
         infos = self.repo.remote().pull()
         for info in infos:
             if info.flags & info.ERROR:
-                raise SCMError("pull failed: {}".format(info.note))
+                raise SCMError(f"pull failed: {info.note}")
 
     def push(self):
         infos = self.repo.remote().push()
         for info in infos:
             if info.flags & info.ERROR:
-                raise SCMError("push failed: {}".format(info.summary))
+                raise SCMError(f"push failed: {info.summary}")
 
     def branch(self, branch):
         self.repo.git.branch(branch)
@@ -296,7 +296,7 @@ class Git(Base):
     def _install_hook(self, name):
         hook = self._hook_path(name)
         with open(hook, "w+") as fobj:
-            fobj.write("#!/bin/sh\nexec dvc git-hook {} $@\n".format(name))
+            fobj.write(f"#!/bin/sh\nexec dvc git-hook {name} $@\n")
 
         os.chmod(hook, 0o777)
 
@@ -312,7 +312,7 @@ class Git(Base):
 
         config = {}
         if os.path.exists(config_path):
-            with open(config_path, "r") as fobj:
+            with open(config_path) as fobj:
                 config = yaml.safe_load(fobj)
 
         entry = {
@@ -404,15 +404,15 @@ class Git(Base):
         # Try all the remotes and if it resolves unambiguously then take it
         if not Git.is_sha(rev):
             shas = {
-                _resolve_rev("{}/{}".format(remote.name, rev))
+                _resolve_rev(f"{remote.name}/{rev}")
                 for remote in self.repo.remotes
             } - {None}
             if len(shas) > 1:
-                raise RevError("ambiguous Git revision '{}'".format(rev))
+                raise RevError(f"ambiguous Git revision '{rev}'")
             if len(shas) == 1:
                 return shas.pop()
 
-        raise RevError("unknown Git revision '{}'".format(rev))
+        raise RevError(f"unknown Git revision '{rev}'")
 
     def has_rev(self, rev):
         try:

dvc/scm/git/tree.py

@@ -42,10 +42,10 @@ class GitTree(BaseTree):
 
         obj = self.git_object_by_path(path)
         if obj is None:
-            msg = "No such file in branch '{}'".format(self.rev)
-            raise IOError(errno.ENOENT, msg, relative_path)
+            msg = f"No such file in branch '{self.rev}'"
+            raise OSError(errno.ENOENT, msg, relative_path)
         if obj.mode == GIT_MODE_DIR:
-            raise IOError(errno.EISDIR, "Is a directory", relative_path)
+            raise OSError(errno.EISDIR, "Is a directory", relative_path)
 
         # GitPython's obj.data_stream is a fragile thing, it is better to
         # read it immediately, also it needs to be to decoded if we follow
@@ -135,6 +135,6 @@ class GitTree(BaseTree):
 
         tree = self.git_object_by_path(top)
         if tree is None:
-            raise IOError(errno.ENOENT, "No such file")
+            raise OSError(errno.ENOENT, "No such file")
 
         yield from self._walk(tree, topdown=topdown)

dvc/scm/tree.py

@@ -2,7 +2,7 @@ import os
 import stat
 
 
-class BaseTree(object):
+class BaseTree:
     """Abstract class to represent access to files"""
 
     @property

dvc/stage/__init__.py

@@ -277,7 +277,7 @@ class Stage(params.StageParams):
                 out.unprotect()
                 continue
 
-            logger.debug("Removing output '{}' of {}.".format(out, self))
+            logger.debug(f"Removing output '{out}' of {self}.")
             out.remove(ignore_remove=ignore_remove)
 
     def unprotect_outs(self):
@@ -308,7 +308,7 @@ class Stage(params.StageParams):
 
         self.run(**kwargs)
 
-        logger.debug("{stage} was reproduced".format(stage=self))
+        logger.debug(f"{self} was reproduced")
 
         return self
 
@@ -357,7 +357,7 @@ class Stage(params.StageParams):
 
     def compute_md5(self):
         m = compute_md5(self)
-        logger.debug("Computed {} md5: '{}'".format(self, m))
+        logger.debug(f"Computed {self} md5: '{m}'")
         return m
 
     def save(self):
@@ -384,7 +384,7 @@ class Stage(params.StageParams):
         ]
 
     def _changed_stage_entry(self):
-        return "'md5' of {} changed.".format(self)
+        return f"'md5' of {self} changed."
 
     def changed_entries(self):
         changed_deps = self._changed_entries(self.deps)
@@ -558,4 +558,4 @@ class PipelineStage(Stage):
         return self.cmd_changed
 
     def _changed_stage_entry(self):
-        return "'cmd' of {} has changed.".format(self)
+        return f"'cmd' of {self} has changed."

dvc/stage/cache.py

@@ -52,7 +52,7 @@ class StageCache:
         path = self._get_cache_path(key, value)
 
         try:
-            with open(path, "r") as fobj:
+            with open(path) as fobj:
                 return COMPILED_LOCK_FILE_STAGE_SCHEMA(yaml.safe_load(fobj))
         except FileNotFoundError:
             return None

dvc/stage/exceptions.py

@@ -3,9 +3,9 @@ from dvc.exceptions import DvcException
 
 class StageCmdFailedError(DvcException):
     def __init__(self, cmd, status=None):
-        msg = "failed to run: {}".format(cmd)
+        msg = f"failed to run: {cmd}"
         if status is not None:
-            msg += ", exited with {}".format(status)
+            msg += f", exited with {status}"
         super().__init__(msg)
 
 
@@ -19,18 +19,18 @@ class StageFileDoesNotExistError(DvcException):
     def __init__(self, fname):
         from dvc.dvcfile import DVC_FILE_SUFFIX, is_dvc_file
 
-        msg = "'{}' does not exist.".format(fname)
+        msg = f"'{fname}' does not exist."
 
         sname = fname + DVC_FILE_SUFFIX
         if is_dvc_file(sname):
-            msg += " Do you mean '{}'?".format(sname)
+            msg += f" Do you mean '{sname}'?"
 
         super().__init__(msg)
 
 
 class StageFileAlreadyExistsError(DvcException):
     def __init__(self, relpath):
-        msg = "not overwriting '{}'".format(relpath)
+        msg = f"not overwriting '{relpath}'"
         super().__init__(msg)
 
 
@@ -38,11 +38,11 @@ class StageFileIsNotDvcFileError(DvcException):
     def __init__(self, fname):
         from dvc.dvcfile import DVC_FILE_SUFFIX, is_dvc_file
 
-        msg = "'{}' is not a DVC-file".format(fname)
+        msg = f"'{fname}' is not a DVC-file"
 
         sname = fname + DVC_FILE_SUFFIX
         if is_dvc_file(sname):
-            msg += " Do you mean '{}'?".format(sname)
+            msg += f" Do you mean '{sname}'?"
 
         super().__init__(msg)
 
@@ -90,7 +90,7 @@ class MissingDataSource(DvcException):
 class StageNotFound(KeyError, DvcException):
     def __init__(self, file, name):
         super().__init__(
-            "Stage '{}' not found inside '{}' file".format(name, file.relpath)
+            f"Stage '{name}' not found inside '{file.relpath}' file"
         )
 
 
@@ -98,7 +98,7 @@ class StageNameUnspecified(DvcException):
     def __init__(self, file):
         super().__init__(
             "Stage name not provided."
-            "Please specify the name as: `{0}:stage_name`".format(file.relpath)
+            "Please specify the name as: `{}:stage_name`".format(file.relpath)
         )
 
 

dvc/state.py

@@ -29,7 +29,7 @@ class StateVersionTooNewError(DvcException):
         )
 
 
-class StateNoop(object):
+class StateNoop:
     files = []
 
     def save(self, path_info, checksum):
@@ -48,7 +48,7 @@ class StateNoop(object):
         pass
 
 
-class State(object):  # pylint: disable=too-many-instance-attributes
+class State:  # pylint: disable=too-many-instance-attributes
     """Class for the state database.
 
     Args:
@@ -440,7 +440,7 @@ class State(object):  # pylint: disable=too-many-instance-attributes
         """
         unused = []
 
-        self._execute("SELECT * FROM {}".format(self.LINK_STATE_TABLE))
+        self._execute(f"SELECT * FROM {self.LINK_STATE_TABLE}")
         for row in self.cursor:
             relpath, inode, mtime = row
             inode = self._from_sqlite(inode)

dvc/system.py

@@ -22,7 +22,7 @@ if (
         pass
 
 
-class System(object):
+class System:
     @staticmethod
     def is_unix():
         return os.name != "nt"
@@ -89,7 +89,7 @@ class System(object):
 
         try:
             ret = 255
-            with open(src, "r") as s, open(dst, "w+") as d:
+            with open(src) as s, open(dst, "w+") as d:
                 ret = fcntl.ioctl(d.fileno(), FICLONE, s.fileno())
         finally:
             if ret != 0:
@@ -111,7 +111,7 @@ class System(object):
                 ret = System._reflink_linux(source, link_name)
             else:
                 ret = -1
-        except IOError:
+        except OSError:
             ret = -1
 
         if ret != 0:

dvc/updater.py

@@ -14,7 +14,7 @@ from dvc.utils.pkg import PKG
 logger = logging.getLogger(__name__)
 
 
-class Updater(object):  # pragma: no cover
+class Updater:  # pragma: no cover
     URL = "https://updater.dvc.org"
     UPDATER_FILE = "updater"
     TIMEOUT = 24 * 60 * 60  # every day
@@ -34,7 +34,7 @@ class Updater(object):  # pragma: no cover
         ctime = os.path.getmtime(self.updater_file)
         outdated = time.time() - ctime >= self.TIMEOUT
         if outdated:
-            logger.debug("'{}' is outdated(".format(self.updater_file))
+            logger.debug(f"'{self.updater_file}' is outdated(")
         return outdated
 
     def _with_lock(self, func, action):
@@ -56,7 +56,7 @@ class Updater(object):  # pragma: no cover
             self.fetch()
             return
 
-        with open(self.updater_file, "r") as fobj:
+        with open(self.updater_file) as fobj:
             import json
 
             try:

dvc/utils/fs.py

@@ -96,7 +96,7 @@ def move(src, dst, mode=None):
     """
 
     dst = os.path.abspath(dst)
-    tmp = "{}.{}".format(dst, uuid())
+    tmp = f"{dst}.{uuid()}"
 
     if os.path.islink(src):
         # readlink does not accept path-like obj for Windows in Python <3.8

dvc/utils/http.py

@@ -30,7 +30,7 @@ def iter_url(url, chunk_size=io.DEFAULT_BUFFER_SIZE):
         the_url = url() if callable(url) else url
         response = requests.get(the_url, stream=True, headers=headers)
         if response.status_code == 404:
-            raise FileNotFoundError("Can't open {}".format(the_url))
+            raise FileNotFoundError(f"Can't open {the_url}")
         response.raise_for_status()
         return response
 
@@ -49,7 +49,7 @@ def iter_url(url, chunk_size=io.DEFAULT_BUFFER_SIZE):
                         raise
 
                     # Reopen request from where we stopped
-                    headers = {"Range": "bytes={}-".format(pos)}
+                    headers = {"Range": f"bytes={pos}-"}
                     response = request(headers)
         finally:
             response.close()

dvc/utils/stage.py

@@ -13,7 +13,7 @@ except ImportError:
 
 
 def load_stage_file(path):
-    with open(path, "r", encoding="utf-8") as fd:
+    with open(path, encoding="utf-8") as fd:
         return parse_stage(fd.read(), path)
 
 

tests/basic_env.py

@@ -1,5 +1,3 @@
-# encoding: utf-8
-
 import logging
 import os
 import tempfile
@@ -17,7 +15,7 @@ from dvc.utils.fs import remove
 logger = logging.getLogger("dvc")
 
 
-class TestDirFixture(object):
+class TestDirFixture:
     DATA_DIR = "data_dir"
     DATA_SUB_DIR = os.path.join(DATA_DIR, "data_sub_dir")
     DATA = os.path.join(DATA_DIR, "data")
@@ -76,8 +74,8 @@ class TestDirFixture(object):
 
     @staticmethod
     def mkdtemp(base_directory=None):
-        prefix = "dvc-test.{}.".format(os.getpid())
-        suffix = ".{}".format(shortuuid.uuid())
+        prefix = f"dvc-test.{os.getpid()}."
+        suffix = f".{shortuuid.uuid()}"
         return tempfile.mkdtemp(
             prefix=prefix, suffix=suffix, dir=base_directory
         )

tests/conftest.py

@@ -31,7 +31,7 @@ def reset_loglevel(request, caplog):
 here = os.path.abspath(os.path.dirname(__file__))
 
 user = "user"
-key_path = os.path.join(here, "{0}.key".format(user))
+key_path = os.path.join(here, f"{user}.key")
 
 
 @pytest.fixture

tests/dir_helpers.py

@@ -79,7 +79,7 @@ class TmpDir(pathlib.Path):
         self = cls._from_parts(args, init=False)
         if not self._flavour.is_supported:
             raise NotImplementedError(
-                "cannot instantiate %r on your system" % (cls.__name__,)
+                f"cannot instantiate {cls.__name__!r} on your system"
             )
         self._init()
         return self
@@ -263,10 +263,10 @@ def run_copy(tmp_dir, dvc):
 
     def run_copy(src, dst, **run_kwargs):
         return dvc.run(
-            cmd="python copy.py {} {}".format(src, dst),
+            cmd=f"python copy.py {src} {dst}",
             outs=[dst],
             deps=[src, "copy.py"],
-            **run_kwargs
+            **run_kwargs,
         )
 
     return run_copy
@@ -328,7 +328,7 @@ def setup_remote(make_tmp_dir):
                 conf["core"]["remote"] = name
 
         repo.scm.add(repo.config.files["repo"])
-        repo.scm.commit("add '{}' remote".format(name))
+        repo.scm.commit(f"add '{name}' remote")
         return url
 
     return create

tests/func/remote/test_gdrive.py

@@ -44,7 +44,7 @@ def test_relative_user_credentials_file_config_setting(tmp_dir, dvc):
     # Check that in config we got the path relative to the config file itself
     # Also, we store posix path even on Windows
     config = configobj.ConfigObj(repo.config.files["repo"])
-    assert config['remote "{}"'.format(remote_name)][
+    assert config[f'remote "{remote_name}"'][
         "gdrive_user_credentials_file"
     ] == posixpath.join("..", "secrets", "credentials.json")
 

tests/func/test_add.py

@@ -49,7 +49,7 @@ def test_add(tmp_dir, dvc):
 
 def test_add_unicode(tmp_dir, dvc):
     with open("\xe1", "wb") as fd:
-        fd.write("something".encode("utf-8"))
+        fd.write(b"something")
 
     (stage,) = dvc.add("\xe1")
 
@@ -206,7 +206,7 @@ class TestAddLocalRemoteFile(TestDvc):
 
         self.dvc = DvcRepo()
 
-        foo = "remote://{}/{}".format(remote, self.FOO)
+        foo = f"remote://{remote}/{self.FOO}"
         ret = main(["add", foo])
         self.assertEqual(ret, 0)
 
@@ -525,7 +525,7 @@ def temporary_windows_drive(tmp_path_factory):
     new_drive_name = [
         letter for letter in string.ascii_uppercase if letter not in drives
     ][0]
-    new_drive = "{}:".format(new_drive_name)
+    new_drive = f"{new_drive_name}:"
 
     target_path = tmp_path_factory.mktemp("tmp_windows_drive")
 

tests/func/test_api.py

@@ -41,7 +41,7 @@ def test_get_url_external(erepo_dir, remote_url, setup_remote):
         erepo_dir.dvc_gen("foo", "foo", commit="add foo")
 
     # Using file url to force clone to tmp repo
-    repo_url = "file://{}".format(erepo_dir)
+    repo_url = f"file://{erepo_dir}"
     expected_url = URLInfo(remote_url) / "ac/bd18db4cc2f85cedef654fccc4a4d8"
     assert api.get_url("foo", repo=repo_url) == expected_url
 
@@ -53,7 +53,7 @@ def test_get_url_requires_dvc(tmp_dir, scm):
         api.get_url("foo", repo=os.fspath(tmp_dir))
 
     with pytest.raises(UrlNotDvcRepoError):
-        api.get_url("foo", repo="file://{}".format(tmp_dir))
+        api.get_url("foo", repo=f"file://{tmp_dir}")
 
 
 @pytest.mark.parametrize("remote_url", all_remote_params, indirect=True)
@@ -86,7 +86,7 @@ def test_open_external(remote_url, erepo_dir, setup_remote):
     remove(erepo_dir.dvc.cache.local.cache_dir)
 
     # Using file url to force clone to tmp repo
-    repo_url = "file://{}".format(erepo_dir)
+    repo_url = f"file://{erepo_dir}"
     with api.open("version", repo=repo_url) as fd:
         assert fd.read() == "master"
 
@@ -121,7 +121,7 @@ def test_open_not_cached(dvc):
     dvc.run(
         single_stage=True,
         metrics_no_cache=[metric_file],
-        cmd=('python -c "{}"'.format(metric_code)),
+        cmd=(f'python -c "{metric_code}"'),
     )
 
     with api.open(metric_file) as fd:

tests/func/test_checkout.py

@@ -257,7 +257,7 @@ class TestGitIgnoreBasic(CheckoutBase):
         self.commit_data_file(fname2)
         self.dvc.run(
             single_stage=True,
-            cmd="python {} {} {}".format(self.CODE, self.FOO, fname3),
+            cmd=f"python {self.CODE} {self.FOO} {fname3}",
             deps=[self.CODE, self.FOO],
             outs_no_cache=[fname3],
         )

tests/func/test_cli.py

@@ -164,7 +164,7 @@ class TestFindRoot(TestDvc):
     def test(self):
         os.chdir("..")
 
-        class A(object):
+        class A:
             quiet = False
             verbose = True
 

tests/func/test_config.py

@@ -34,7 +34,7 @@ class TestConfigCLI(TestDvc):
     def _do_test(self, local=False):
         section = "core"
         field = "analytics"
-        section_field = "{}.{}".format(section, field)
+        section_field = f"{section}.{field}"
         value = "True"
         newvalue = "False"
 

tests/func/test_data_cloud.py

@@ -87,9 +87,7 @@ class TestDataCloudBase(TestDvc):
 
     def _ensure_should_run(self):
         if not self.should_test():
-            raise SkipTest(
-                "Test {} is disabled".format(self.__class__.__name__)
-            )
+            raise SkipTest(f"Test {self.__class__.__name__} is disabled")
 
     def _setup_cloud(self):
         self._ensure_should_run()
@@ -167,7 +165,7 @@ class TestDataCloudBase(TestDvc):
             self.cloud.pull(info)
             self.assertTrue(os.path.exists(cache))
             self.assertTrue(os.path.isfile(cache))
-            with open(cache, "r") as fd:
+            with open(cache) as fd:
                 self.assertEqual(fd.read(), self.FOO_CONTENTS)
 
             self.cloud.pull(info_dir)
@@ -366,7 +364,7 @@ class TestDataCloudCLIBase(TestDvc):
         self.assertTrue(os.path.isfile(self.FOO))
         self.assertTrue(os.path.isdir(self.DATA_DIR))
 
-        with open(cache, "r") as fd:
+        with open(cache) as fd:
             self.assertEqual(fd.read(), self.FOO_CONTENTS)
         self.assertTrue(os.path.isfile(cache_dir))
 
@@ -391,9 +389,7 @@ class TestDataCloudCLIBase(TestDvc):
 
     def test(self):
         if not self.should_test():
-            raise SkipTest(
-                "Test {} is disabled".format(self.__class__.__name__)
-            )
+            raise SkipTest(f"Test {self.__class__.__name__} is disabled")
         self._test()
 
 

tests/func/test_external_repo.py

@@ -51,7 +51,7 @@ def test_cache_reused(erepo_dir, mocker, setup_remote):
     download_spy = mocker.spy(LocalRemote, "download")
 
     # Use URL to prevent any fishy optimizations
-    url = "file://{}".format(erepo_dir)
+    url = f"file://{erepo_dir}"
     with external_repo(url) as repo:
         repo.fetch()
         assert download_spy.mock.call_count == 1
@@ -66,7 +66,7 @@ def test_cache_reused(erepo_dir, mocker, setup_remote):
 def test_known_sha(erepo_dir):
     erepo_dir.scm.commit("init")
 
-    url = "file://{}".format(erepo_dir)
+    url = f"file://{erepo_dir}"
     with external_repo(url) as repo:
         rev = repo.scm.get_rev()
         prev_rev = repo.scm.resolve_rev("HEAD^")

tests/func/test_ignore.py

@@ -1,4 +1,3 @@
-# encoding: utf-8
 import os
 import shutil
 

tests/func/test_import.py

@@ -141,9 +141,7 @@ def test_import_non_cached(erepo_dir, tmp_dir, dvc, scm):
 
     with erepo_dir.chdir():
         erepo_dir.dvc.run(
-            cmd="echo hello > {}".format(src),
-            outs_no_cache=[src],
-            single_stage=True,
+            cmd=f"echo hello > {src}", outs_no_cache=[src], single_stage=True,
         )
 
     erepo_dir.scm_add(

tests/func/test_install.py

@@ -11,7 +11,7 @@ from dvc.utils import file_md5
 @pytest.mark.skipif(
     sys.platform == "win32", reason="Git hooks aren't supported on Windows"
 )
-class TestInstall(object):
+class TestInstall:
     def _hook(self, name):
         return pathlib.Path(".git") / "hooks" / name
 

tests/func/test_ls.py

@@ -298,7 +298,7 @@ def test_ls_remote_repo(erepo_dir):
         erepo_dir.scm_gen(FS_STRUCTURE, commit="init")
         erepo_dir.dvc_gen(DVC_STRUCTURE, commit="dvc")
 
-    url = "file://{}".format(erepo_dir)
+    url = f"file://{erepo_dir}"
     files = Repo.ls(url)
     match_files(
         files,
@@ -318,7 +318,7 @@ def test_ls_remote_repo_recursive(erepo_dir):
         erepo_dir.scm_gen(FS_STRUCTURE, commit="init")
         erepo_dir.dvc_gen(DVC_STRUCTURE, commit="dvc")
 
-    url = "file://{}".format(erepo_dir)
+    url = f"file://{erepo_dir}"
     files = Repo.ls(url, recursive=True)
     match_files(
         files,
@@ -346,7 +346,7 @@ def test_ls_remote_git_only_repo_recursive(git_dir):
     with git_dir.chdir():
         git_dir.scm_gen(FS_STRUCTURE, commit="init")
 
-    url = "file://{}".format(git_dir)
+    url = f"file://{git_dir}"
     files = Repo.ls(url, recursive=True)
     match_files(
         files,
@@ -364,7 +364,7 @@ def test_ls_remote_repo_with_path_dir(erepo_dir):
         erepo_dir.scm_gen(FS_STRUCTURE, commit="init")
         erepo_dir.dvc_gen(DVC_STRUCTURE, commit="dvc")
 
-    url = "file://{}".format(erepo_dir)
+    url = f"file://{erepo_dir}"
     path = "model"
     files = Repo.ls(url, path)
     match_files(
@@ -385,7 +385,7 @@ def test_ls_remote_repo_with_rev(erepo_dir):
         erepo_dir.dvc_gen(DVC_STRUCTURE, commit="dvc")
 
     rev = erepo_dir.scm.list_all_commits()[1]
-    url = "file://{}".format(erepo_dir)
+    url = f"file://{erepo_dir}"
     files = Repo.ls(url, rev=rev)
     match_files(
         files,
@@ -403,7 +403,7 @@ def test_ls_remote_repo_with_rev_recursive(erepo_dir):
         erepo_dir.scm_gen(FS_STRUCTURE, commit="init")
 
     rev = erepo_dir.scm.list_all_commits()[1]
-    url = "file://{}".format(erepo_dir)
+    url = f"file://{erepo_dir}"
     files = Repo.ls(url, rev=rev, recursive=True)
     match_files(
         files,

tests/func/test_move.py

@@ -140,7 +140,7 @@ class TestMoveDirectoryShouldNotOverwriteExisting(TestDvcGit):
         self.assertTrue(os.path.exists(dir_name))
         self.assertEqual(
             set(os.listdir(dir_name)),
-            set([".gitignore", data_dir_stage, self.DATA_DIR]),
+            {".gitignore", data_dir_stage, self.DATA_DIR},
         )
 
         self.assertTrue(os.path.exists(new_dir_name))

tests/func/test_remote.py

@@ -265,7 +265,7 @@ def test_remote_modify_validation(dvc):
         == 251
     )
     config = configobj.ConfigObj(dvc.config.files["repo"])
-    assert unsupported_config not in config['remote "{}"'.format(remote_name)]
+    assert unsupported_config not in config[f'remote "{remote_name}"']
 
 
 def test_remote_modify_default(dvc):

tests/func/test_repo.py

@@ -58,11 +58,11 @@ def test_destroy(tmp_dir, dvc, run_copy):
 
 def test_collect(tmp_dir, scm, dvc, run_copy):
     def collect_outs(*args, **kwargs):
-        return set(
+        return {
             str(out)
             for stage in dvc.collect(*args, **kwargs)
             for out in stage.outs
-        )
+        }
 
     tmp_dir.dvc_gen("foo", "foo")
     run_copy("foo", "bar", single_stage=True)
@@ -100,7 +100,7 @@ def test_collect(tmp_dir, scm, dvc, run_copy):
 
 def test_stages(tmp_dir, dvc):
     def stages():
-        return set(stage.relpath for stage in Repo(os.fspath(tmp_dir)).stages)
+        return {stage.relpath for stage in Repo(os.fspath(tmp_dir)).stages}
 
     tmp_dir.dvc_gen({"file": "a", "dir/file": "b", "dir/subdir/file": "c"})
 

tests/func/test_repro.py

@@ -74,7 +74,7 @@ class TestRepro(SingleStageRun, TestDvc):
             fname=self.file1_stage,
             outs=[self.file1],
             deps=[self.FOO, self.CODE],
-            cmd="python {} {} {}".format(self.CODE, self.FOO, self.file1),
+            cmd=f"python {self.CODE} {self.FOO} {self.file1}",
             name="run1",
         )
 
@@ -146,7 +146,7 @@ class TestReproWorkingDirectoryAsOutput(TestDvc):
 
         output = os.path.join("..", "something")
         stage_dump = {
-            "cmd": "echo something > {}".format(output),
+            "cmd": f"echo something > {output}",
             "outs": [{"path": output}],
         }
         dump_stage_file(faulty_stage_path, stage_dump)
@@ -175,7 +175,7 @@ class TestReproWorkingDirectoryAsOutput(TestDvc):
             fname=os.path.join(dir1, "b.dvc"),
             wdir=dir1,
             outs=[out_dir],  # ../a/nested
-            cmd="mkdir {path}".format(path=out_dir),
+            cmd=f"mkdir {out_dir}",
             single_stage=True,
         )
 
@@ -185,7 +185,7 @@ class TestReproWorkingDirectoryAsOutput(TestDvc):
 
         output = os.path.join("..", "..", "something")
         stage_dump = {
-            "cmd": "echo something > {}".format(output),
+            "cmd": f"echo something > {output}",
             "outs": [{"path": output}],
         }
         dump_stage_file(error_stage_path, stage_dump)
@@ -240,7 +240,7 @@ class TestReproDepUnderDir(SingleStageRun, TestDvc):
             fname=self.file1 + ".dvc",
             outs=[self.file1],
             deps=[self.DATA, self.CODE],
-            cmd="python {} {} {}".format(self.CODE, self.DATA, self.file1),
+            cmd=f"python {self.CODE} {self.DATA} {self.file1}",
             name="copy-data-file1",
         )
 
@@ -277,7 +277,7 @@ class TestReproDepDirWithOutputsUnderIt(SingleStageRun, TestDvc):
             fname=file1_stage,
             deps=[self.DATA_DIR],
             outs=[file1],
-            cmd="python {} {} {}".format(self.CODE, self.DATA, file1),
+            cmd=f"python {self.CODE} {self.DATA} {file1}",
             name="copy-data-file1",
         )
         self.assertTrue(stage is not None)
@@ -303,7 +303,7 @@ class TestReproNoDeps(TestRepro):
         stage = self._run(
             fname=stage_file,
             outs=[out],
-            cmd="python {}".format(code_file),
+            cmd=f"python {code_file}",
             name="uuid",
         )
 
@@ -377,8 +377,8 @@ class TestReproDryNoExec(TestDvc):
     def test(self):
         deps = []
         for d in range(3):
-            idir = "idir{}".format(d)
-            odir = "odir{}".format(d)
+            idir = f"idir{d}"
+            odir = f"odir{d}"
 
             deps.append("-d")
             deps.append(odir)
@@ -422,7 +422,7 @@ class TestReproChangedDeepData(TestReproChangedData):
             fname=self.file2 + ".dvc",
             outs=[self.file2],
             deps=[self.file1, self.CODE],
-            cmd="python {} {} {}".format(self.CODE, self.file1, self.file2),
+            cmd=f"python {self.CODE} {self.file1} {self.file2}",
             name="copy-file-file2",
         )
 
@@ -449,7 +449,7 @@ class TestReproForceDownstream(TestDvc):
         file1_stage = self.dvc.run(
             outs=[file1],
             deps=[self.FOO, code1],
-            cmd="python {} {} {}".format(code1, self.FOO, file1),
+            cmd=f"python {code1} {self.FOO} {file1}",
             single_stage=True,
         )
         self.assertTrue(file1_stage is not None)
@@ -460,7 +460,7 @@ class TestReproForceDownstream(TestDvc):
         file2_stage = self.dvc.run(
             outs=[file2],
             deps=[file1, code2],
-            cmd="python {} {} {}".format(code2, file1, file2),
+            cmd=f"python {code2} {file1} {file2}",
             single_stage=True,
         )
         self.assertTrue(file2_stage is not None)
@@ -471,7 +471,7 @@ class TestReproForceDownstream(TestDvc):
         file3_stage = self.dvc.run(
             outs=[file3],
             deps=[file2, code3],
-            cmd="python {} {} {}".format(code3, file2, file3),
+            cmd=f"python {code3} {file2} {file3}",
             single_stage=True,
         )
         self.assertTrue(file3_stage is not None)
@@ -518,7 +518,7 @@ class TestReproPipelines(SingleStageRun, TestDvc):
             fname=self.file1 + ".dvc",
             outs=[self.file1],
             deps=[self.FOO, self.CODE],
-            cmd="python {} {} {}".format(self.CODE, self.FOO, self.file1),
+            cmd=f"python {self.CODE} {self.FOO} {self.file1}",
             single_stage=True,
         )
 
@@ -527,7 +527,7 @@ class TestReproPipelines(SingleStageRun, TestDvc):
             fname=self.file2 + ".dvc",
             outs=[self.file2],
             deps=[self.BAR, self.CODE],
-            cmd="python {} {} {}".format(self.CODE, self.BAR, self.file2),
+            cmd=f"python {self.CODE} {self.BAR} {self.file2}",
             name="copy-BAR-file2",
         )
 
@@ -549,7 +549,7 @@ class TestReproLocked(TestReproChangedData):
             fname=file2 + ".dvc",
             outs=[file2],
             deps=[self.file1, self.CODE],
-            cmd="python {} {} {}".format(self.CODE, self.file1, file2),
+            cmd=f"python {self.CODE} {self.file1} {file2}",
             name="copy-file1-file2",
         )
 
@@ -590,7 +590,7 @@ class TestReproLockedCallback(SingleStageRun, TestDvc):
         stage = self._run(
             fname=file1_stage,
             outs=[file1],
-            cmd="python {} {} {}".format(self.CODE, self.FOO, file1),
+            cmd=f"python {self.CODE} {self.FOO} {file1}",
             name="copy-FOO-file1",
         )
         self.assertTrue(stage is not None)
@@ -637,7 +637,7 @@ class TestReproMetricsAddUnchanged(TestDvc):
             fname=file1_stage,
             outs_no_cache=[file1],
             deps=[self.FOO, self.CODE],
-            cmd="python {} {} {}".format(self.CODE, self.FOO, file1),
+            cmd=f"python {self.CODE} {self.FOO} {file1}",
             single_stage=True,
         )
 
@@ -702,7 +702,7 @@ class TestReproChangedDir(SingleStageRun, TestDvc):
         stage = self._run(
             outs=[dir_name],
             deps=[file_name, dir_code],
-            cmd="python {}".format(dir_code),
+            cmd=f"python {dir_code}",
             name="copy-in-dir",
         )
         target = self._get_stage_target(stage)
@@ -731,7 +731,7 @@ class TestReproChangedDirData(SingleStageRun, TestDvc):
         stage = self._run(
             outs=[dir_name],
             deps=[self.DATA_DIR, dir_code],
-            cmd="python {} {} {}".format(dir_code, self.DATA_DIR, dir_name),
+            cmd=f"python {dir_code} {self.DATA_DIR} {dir_name}",
             name="copy-dir",
         )
         target = self._get_stage_target(stage)
@@ -801,14 +801,14 @@ class TestCmdReproChdir(TestDvc):
                 "run",
                 "--single-stage",
                 "-f",
-                "{}/Dvcfile".format(dname),
+                f"{dname}/Dvcfile",
                 "-w",
-                "{}".format(dname),
+                f"{dname}",
                 "-d",
                 self.FOO,
                 "-o",
                 self.BAR,
-                "python {} {} {}".format(self.CODE, self.FOO, self.BAR),
+                f"python {self.CODE} {self.FOO} {self.BAR}",
             ]
         )
         self.assertEqual(ret, 0)
@@ -878,9 +878,7 @@ class TestReproExternalBase(SingleStageRun, TestDvc):
     @patch("dvc.prompt.confirm", return_value=True)
     def test(self, mock_prompt):
         if not self.should_test():
-            raise SkipTest(
-                "Test {} is disabled".format(self.__class__.__name__)
-            )
+            raise SkipTest(f"Test {self.__class__.__name__} is disabled")
 
         cache = (
             self.scheme
@@ -991,7 +989,7 @@ class TestReproExternalS3(S3, TestReproExternalBase):
         return TEST_AWS_REPO_BUCKET
 
     def cmd(self, i, o):
-        return "aws s3 cp {} {}".format(i, o)
+        return f"aws s3 cp {i} {o}"
 
     def write(self, bucket, key, body):
         s3 = boto3.client("s3")
@@ -1008,7 +1006,7 @@ class TestReproExternalGS(GCP, TestReproExternalBase):
         return TEST_GCP_REPO_BUCKET
 
     def cmd(self, i, o):
-        return "gsutil cp {} {}".format(i, o)
+        return f"gsutil cp {i} {o}"
 
     def write(self, bucket, key, body):
         client = gc.Client()
@@ -1023,15 +1021,15 @@ class TestReproExternalHDFS(HDFS, TestReproExternalBase):
 
     @property
     def bucket(self):
-        return "{}@127.0.0.1".format(getpass.getuser())
+        return f"{getpass.getuser()}@127.0.0.1"
 
     def cmd(self, i, o):
-        return "hadoop fs -cp {} {}".format(i, o)
+        return f"hadoop fs -cp {i} {o}"
 
     def write(self, bucket, key, body):
         url = self.scheme + "://" + bucket + "/" + key
         p = Popen(
-            "hadoop fs -rm -f {}".format(url),
+            f"hadoop fs -rm -f {url}",
             shell=True,
             executable=os.getenv("SHELL"),
             stdin=PIPE,
@@ -1085,14 +1083,14 @@ class TestReproExternalSSH(SSH, TestReproExternalBase):
     def bucket(self):
         if not self._dir:
             self._dir = self.mkdtemp()
-        return "{}@127.0.0.1:{}".format(getpass.getuser(), self._dir)
+        return f"{getpass.getuser()}@127.0.0.1:{self._dir}"
 
     def cmd(self, i, o):
         prefix = "ssh://"
         assert i.startswith(prefix) and o.startswith(prefix)
         i = i[len(prefix) :]
         o = o[len(prefix) :]
-        return "scp {} {}".format(i, o)
+        return f"scp {i} {o}"
 
     def write(self, bucket, key, body):
         path = posixpath.join(self._dir, key)
@@ -1106,12 +1104,10 @@ class TestReproExternalSSH(SSH, TestReproExternalBase):
         try:
             sftp.stat(path)
             sftp.remove(path)
-        except IOError:
+        except OSError:
             pass
 
-        stdin, stdout, stderr = ssh.exec_command(
-            "mkdir -p $(dirname {})".format(path)
-        )
+        stdin, stdout, stderr = ssh.exec_command(f"mkdir -p $(dirname {path})")
         self.assertEqual(stdout.channel.recv_exit_status(), 0)
 
         with sftp.open(path, "w+") as fobj:
@@ -1150,8 +1146,8 @@ class TestReproExternalLOCAL(Local, TestReproExternalBase):
 
     def cmd(self, i, o):
         if os.name == "nt":
-            return "copy {} {}".format(i, o)
-        return "cp {} {}".format(i, o)
+            return f"copy {i} {o}"
+        return f"cp {i} {o}"
 
     def write(self, bucket, key, body):
         path = os.path.join(bucket, key)
@@ -1169,7 +1165,7 @@ class TestReproExternalHTTP(TestReproExternalBase):
 
     @staticmethod
     def get_remote(port):
-        return "http://localhost:{}/".format(port)
+        return f"http://localhost:{port}/"
 
     @property
     def local_cache(self):
@@ -1211,7 +1207,7 @@ class TestReproExternalHTTP(TestReproExternalBase):
 
             run_dependency = urljoin(remote, self.BAR)
             run_output = "remote_file"
-            cmd = 'open("{}", "w+")'.format(run_output)
+            cmd = f'open("{run_output}", "w+")'
 
             with open("create-output.py", "w") as fd:
                 fd.write(cmd)
@@ -1249,18 +1245,18 @@ class TestReproShell(TestDvc):
         self.dvc.run(
             fname=stage,
             outs=[fname],
-            cmd="echo $SHELL > {}".format(fname),
+            cmd=f"echo $SHELL > {fname}",
             single_stage=True,
         )
 
-        with open(fname, "r") as fd:
+        with open(fname) as fd:
             self.assertEqual(os.getenv("SHELL"), fd.read().strip())
 
         os.unlink(fname)
 
         self.dvc.reproduce(stage)
 
-        with open(fname, "r") as fd:
+        with open(fname) as fd:
             self.assertEqual(os.getenv("SHELL"), fd.read().strip())
 
 
@@ -1386,7 +1382,7 @@ class TestShouldDisplayMetricsOnReproWithMetricsOption(TestDvc):
                 "--single-stage",
                 "-m",
                 metrics_file,
-                "echo {} >> {}".format(metrics_value, metrics_file),
+                f"echo {metrics_value} >> {metrics_file}",
             ]
         )
         self.assertEqual(0, ret)
@@ -1400,7 +1396,7 @@ class TestShouldDisplayMetricsOnReproWithMetricsOption(TestDvc):
         )
         self.assertEqual(0, ret)
 
-        expected_metrics_display = "{}: {}".format(metrics_file, metrics_value)
+        expected_metrics_display = f"{metrics_file}: {metrics_value}"
         self.assertIn(expected_metrics_display, self._caplog.text)
 
 

tests/func/test_repro_multistage.py

@@ -492,7 +492,7 @@ def test_cyclic_graph_error(tmp_dir, dvc, run_copy):
     run_copy("bar", "baz", name="copy-bar-baz")
     run_copy("baz", "foobar", name="copy-baz-foobar")
 
-    with open(PIPELINE_FILE, "r") as f:
+    with open(PIPELINE_FILE) as f:
         data = parse_stage(f.read(), PIPELINE_FILE)
         data["stages"]["copy-baz-foo"] = {
             "cmd": "echo baz > foo",

tests/func/test_run_multistage.py

@@ -45,7 +45,7 @@ def test_run_multi_stage_repeat(tmp_dir, dvc, run_copy):
     stages = list(Dvcfile(dvc, PIPELINE_FILE).stages.values())
     assert len(stages) == 2
     assert all(isinstance(stage, PipelineStage) for stage in stages)
-    assert set(stage.name for stage in stages) == {
+    assert {stage.name for stage in stages} == {
         "copy-foo-foo1",
         "copy-foo1-foo2",
     }
@@ -183,7 +183,7 @@ def test_run_dump_on_multistage(tmp_dir, dvc, run_head):
 )
 def test_run_with_invalid_stage_name(run_copy, char):
     with pytest.raises(InvalidStageName):
-        run_copy("foo", "bar", name="copy_name-{}".format(char))
+        run_copy("foo", "bar", name=f"copy_name-{char}")
 
 
 def test_run_with_name_having_hyphen_underscore(tmp_dir, dvc, run_copy):

tests/func/test_run_single_stage.py

@@ -110,7 +110,7 @@ class TestRunNoExec(TestDvcGit):
             single_stage=True,
         )
         self.assertFalse(os.path.exists("out"))
-        with open(".gitignore", "r") as fobj:
+        with open(".gitignore") as fobj:
             self.assertEqual(fobj.read(), "/out\n")
 
 
@@ -233,7 +233,7 @@ class TestRunBadCwd(TestDvc):
 
     def test_same_prefix(self):
         with self.assertRaises(StagePathOutsideError):
-            path = "{}-{}".format(self._root_dir, uuid.uuid4())
+            path = f"{self._root_dir}-{uuid.uuid4()}"
             os.mkdir(path)
             self.dvc.run(cmd="", wdir=path, single_stage=True)
 
@@ -245,7 +245,7 @@ class TestRunBadWdir(TestDvc):
 
     def test_same_prefix(self):
         with self.assertRaises(StagePathOutsideError):
-            path = "{}-{}".format(self._root_dir, uuid.uuid4())
+            path = f"{self._root_dir}-{uuid.uuid4()}"
             os.mkdir(path)
             self.dvc.run(cmd="", wdir=path, single_stage=True)
 
@@ -276,7 +276,7 @@ class TestRunBadName(TestDvc):
 
     def test_same_prefix(self):
         with self.assertRaises(StagePathOutsideError):
-            path = "{}-{}".format(self._root_dir, uuid.uuid4())
+            path = f"{self._root_dir}-{uuid.uuid4()}"
             os.mkdir(path)
             self.dvc.run(
                 cmd="",
@@ -306,7 +306,7 @@ class TestRunRemoveOuts(TestDvc):
         self.dvc.run(
             deps=[self.CODE],
             outs=[self.FOO],
-            cmd="python {} {}".format(self.CODE, self.FOO),
+            cmd=f"python {self.CODE} {self.FOO}",
             single_stage=True,
         )
 
@@ -336,7 +336,7 @@ class TestRunUnprotectOutsCopy(TestDvc):
         )
         self.assertEqual(ret, 0)
         self.assertTrue(os.access(self.FOO, os.W_OK))
-        with open(self.FOO, "r") as fd:
+        with open(self.FOO) as fd:
             self.assertEqual(fd.read(), "foo")
 
         ret = main(
@@ -356,7 +356,7 @@ class TestRunUnprotectOutsCopy(TestDvc):
         )
         self.assertEqual(ret, 0)
         self.assertTrue(os.access(self.FOO, os.W_OK))
-        with open(self.FOO, "r") as fd:
+        with open(self.FOO) as fd:
             self.assertEqual(fd.read(), "foo")
 
 
@@ -394,7 +394,7 @@ class TestRunUnprotectOutsSymlink(TestDvc):
             self.assertFalse(os.access(self.FOO, os.W_OK))
 
         self.assertTrue(System.is_symlink(self.FOO))
-        with open(self.FOO, "r") as fd:
+        with open(self.FOO) as fd:
             self.assertEqual(fd.read(), "foo")
 
         ret = main(
@@ -421,7 +421,7 @@ class TestRunUnprotectOutsSymlink(TestDvc):
             self.assertFalse(os.access(self.FOO, os.W_OK))
 
         self.assertTrue(System.is_symlink(self.FOO))
-        with open(self.FOO, "r") as fd:
+        with open(self.FOO) as fd:
             self.assertEqual(fd.read(), "foo")
 
 
@@ -453,7 +453,7 @@ class TestRunUnprotectOutsHardlink(TestDvc):
         self.assertEqual(ret, 0)
         self.assertFalse(os.access(self.FOO, os.W_OK))
         self.assertTrue(System.is_hardlink(self.FOO))
-        with open(self.FOO, "r") as fd:
+        with open(self.FOO) as fd:
             self.assertEqual(fd.read(), "foo")
 
         ret = main(
@@ -474,7 +474,7 @@ class TestRunUnprotectOutsHardlink(TestDvc):
         self.assertEqual(ret, 0)
         self.assertFalse(os.access(self.FOO, os.W_OK))
         self.assertTrue(System.is_hardlink(self.FOO))
-        with open(self.FOO, "r") as fd:
+        with open(self.FOO) as fd:
             self.assertEqual(fd.read(), "foo")
 
 
@@ -594,7 +594,7 @@ class TestCmdRunCliMetrics(TestDvc):
             ]
         )
         self.assertEqual(ret, 0)
-        with open("metrics.txt", "r") as fd:
+        with open("metrics.txt") as fd:
             self.assertEqual(fd.read().rstrip(), "test")
 
     def test_not_cached(self):
@@ -608,14 +608,14 @@ class TestCmdRunCliMetrics(TestDvc):
             ]
         )
         self.assertEqual(ret, 0)
-        with open("metrics.txt", "r") as fd:
+        with open("metrics.txt") as fd:
             self.assertEqual(fd.read().rstrip(), "test")
 
 
 class TestCmdRunWorkingDirectory(TestDvc):
     def test_default_wdir_is_not_written(self):
         stage = self.dvc.run(
-            cmd="echo test > {}".format(self.FOO),
+            cmd=f"echo test > {self.FOO}",
             outs=[self.FOO],
             wdir=".",
             single_stage=True,
@@ -624,9 +624,7 @@ class TestCmdRunWorkingDirectory(TestDvc):
         self.assertNotIn(Stage.PARAM_WDIR, d.keys())
 
         stage = self.dvc.run(
-            cmd="echo test > {}".format(self.BAR),
-            outs=[self.BAR],
-            single_stage=True,
+            cmd=f"echo test > {self.BAR}", outs=[self.BAR], single_stage=True,
         )
         d = load_stage_file(stage.relpath)
         self.assertNotIn(Stage.PARAM_WDIR, d.keys())
@@ -637,7 +635,7 @@ class TestCmdRunWorkingDirectory(TestDvc):
         foo = os.path.join(dname, self.FOO)
         fname = os.path.join(dname, "stage" + DVC_FILE_SUFFIX)
         stage = self.dvc.run(
-            cmd="echo test > {}".format(foo),
+            cmd=f"echo test > {foo}",
             outs=[foo],
             fname=fname,
             single_stage=True,
@@ -761,7 +759,7 @@ class TestRunPersist(TestDvc):
                 "--single-stage",
                 self.outs_command,
                 file,
-                "echo {} >> {}".format(file_content, file),
+                f"echo {file_content} >> {file}",
             ]
         )
         self.assertEqual(0, ret)
@@ -776,7 +774,7 @@ class TestRunPersist(TestDvc):
         ret = main(["repro", stage_file])
         self.assertEqual(0, ret)
 
-        with open(file, "r") as fobj:
+        with open(file) as fobj:
             lines = fobj.readlines()
         self.assertEqual(2, len(lines))
 
@@ -813,7 +811,7 @@ class TestShouldRaiseOnOverlappingOutputPaths(TestDvc):
         with self.assertRaises(OverlappingOutputPathsError) as err:
             self.dvc.run(
                 outs=[self.DATA],
-                cmd="echo data >> {}".format(self.DATA),
+                cmd=f"echo data >> {self.DATA}",
                 single_stage=True,
             )
         error_output = str(err.exception)
@@ -823,12 +821,9 @@ class TestShouldRaiseOnOverlappingOutputPaths(TestDvc):
 
         self.assertIn("Paths for outs:\n", error_output)
         self.assertIn(
-            "\n'{}'('{}')\n".format(self.DATA_DIR, data_dir_stage),
-            error_output,
-        )
-        self.assertIn(
-            "\n'{}'('{}')\n".format(self.DATA, data_stage), error_output
+            f"\n'{self.DATA_DIR}'('{data_dir_stage}')\n", error_output,
         )
+        self.assertIn(f"\n'{self.DATA}'('{data_stage}')\n", error_output)
         self.assertIn(
             "\noverlap. To avoid unpredictable behaviour, rerun "
             "command with non overlapping outs paths.",
@@ -838,7 +833,7 @@ class TestShouldRaiseOnOverlappingOutputPaths(TestDvc):
 
 class TestRerunWithSameOutputs(TestDvc):
     def _read_content_only(self, path):
-        with open(path, "r") as fobj:
+        with open(path) as fobj:
             return [line.rstrip() for line in fobj]
 
     @property
@@ -852,7 +847,7 @@ class TestRerunWithSameOutputs(TestDvc):
                 "--single-stage",
                 "--outs",
                 self.FOO,
-                "echo {} > {}".format(self.FOO_CONTENTS, self.FOO),
+                f"echo {self.FOO_CONTENTS} > {self.FOO}",
             ]
         )
         self.assertEqual(0, ret)
@@ -867,7 +862,7 @@ class TestRerunWithSameOutputs(TestDvc):
                 self.FOO,
                 "--overwrite-dvcfile",
                 "--single-stage",
-                "echo {} >> {}".format(self.BAR_CONTENTS, self.FOO),
+                f"echo {self.BAR_CONTENTS} >> {self.FOO}",
             ]
         )
         self.assertEqual(0, ret)
@@ -907,7 +902,7 @@ class TestShouldNotCheckoutUponCorruptedLocalHardlinkCache(TestDvc):
         self.dvc = DvcRepo(".")
 
     def test(self):
-        cmd = "python {} {} {}".format(self.CODE, self.FOO, self.BAR)
+        cmd = f"python {self.CODE} {self.FOO} {self.BAR}"
         stage = self.dvc.run(
             deps=[self.FOO], outs=[self.BAR], cmd=cmd, single_stage=True
         )
@@ -959,7 +954,7 @@ class TestPersistentOutput(TestDvc):
 
         # Even if the "immutable" dependency didn't change
         # it should run the command again, as it is "ignoring build cache"
-        with open("greetings", "r") as fobj:
+        with open("greetings") as fobj:
             assert "hello\nhello\n" == fobj.read()
 
 

tests/func/test_stage.py

@@ -94,7 +94,7 @@ class TestReload(TestDvc):
 class TestDefaultWorkingDirectory(TestDvc):
     def test_ignored_in_checksum(self):
         stage = self.dvc.run(
-            cmd="echo test > {}".format(self.FOO),
+            cmd=f"echo test > {self.FOO}",
             deps=[self.BAR],
             outs=[self.FOO],
             single_stage=True,
@@ -128,7 +128,7 @@ class TestExternalRemoteResolution(TestDvc):
                     "--single-stage",
                     "-O",
                     "remote://storage/file",
-                    "echo file > {path}".format(path=file_path),
+                    f"echo file > {file_path}",
                 ]
             )
             == 0

tests/func/test_status.py

@@ -38,7 +38,7 @@ def test_status_non_dvc_repo_import(tmp_dir, dvc, git_dir):
 
     (status,) = dvc.status(["file.dvc"])["file.dvc"]
     assert status == {
-        "changed deps": {"file ({})".format(git_dir): "update available"}
+        "changed deps": {f"file ({git_dir})": "update available"}
     }
 
 

tests/func/test_tree.py

@@ -1,5 +1,3 @@
-# encoding: utf-8
-
 from os.path import join
 
 from dvc.ignore import CleanTree
@@ -36,7 +34,7 @@ class TestWorkingTree(TestDir):
         self.assertFalse(self.tree.isfile("not-existing-file"))
 
 
-class GitTreeTests(object):
+class GitTreeTests:
     def test_open(self):
         self.scm.add([self.FOO, self.UNICODE, self.DATA_DIR])
         self.scm.commit("add")
@@ -90,7 +88,7 @@ class TestGitSubmoduleTree(TestGitSubmodule, GitTreeTests):
         self._pushd(self._root_dir)
 
 
-class AssertWalkEqualMixin(object):
+class AssertWalkEqualMixin:
     def assertWalkEqual(self, actual, expected, msg=None):
         def convert_to_sets(walk_results):
             return [

tests/func/test_utils.py

@@ -1,5 +1,3 @@
-# encoding: utf-8
-
 from dvc import utils
 
 

tests/remotes.py

@@ -180,11 +180,11 @@ class OSS:
 
     @staticmethod
     def get_storagepath():
-        return "{}/{}".format(TEST_OSS_REPO_BUCKET, (uuid.uuid4()))
+        return f"{TEST_OSS_REPO_BUCKET}/{uuid.uuid4()}"
 
     @staticmethod
     def get_url():
-        return "oss://{}".format(OSS.get_storagepath())
+        return f"oss://{OSS.get_storagepath()}"
 
 
 class SSH:
@@ -200,7 +200,7 @@ class SSH:
 
         try:
             check_output(["ssh", "-o", "BatchMode=yes", "127.0.0.1", "ls"])
-        except (CalledProcessError, IOError):
+        except (CalledProcessError, OSError):
             return False
 
         return True
@@ -233,7 +233,7 @@ class SSHMocked:
             drive, path = os.path.splitdrive(path)
             assert drive.lower() == "c:"
             path = path.replace("\\", "/")
-        url = "ssh://{}@127.0.0.1:{}{}".format(user, port, path)
+        url = f"ssh://{user}@127.0.0.1:{port}{path}"
         return url
 
 
@@ -249,7 +249,7 @@ class HDFS:
                 shell=True,
                 executable=os.getenv("SHELL"),
             )
-        except (CalledProcessError, IOError):
+        except (CalledProcessError, OSError):
             return False
 
         p = Popen(
@@ -275,4 +275,4 @@ class HTTP:
 
     @staticmethod
     def get_url(port):
-        return "http://127.0.0.1:{}".format(port)
+        return f"http://127.0.0.1:{port}"

tests/unit/remote/ssh/test_connection.py

@@ -72,7 +72,7 @@ def test_walk(tmp_path, ssh):
         dir_data_path,
         subdir_data_path,
     ]
-    expected = set([entry.absolute().as_posix() for entry in entries])
+    expected = {entry.absolute().as_posix() for entry in entries}
 
     paths = set()
     for root, dirs, files in ssh.walk(root_path.absolute().as_posix()):

tests/unit/remote/ssh/test_ssh.py

@@ -17,14 +17,14 @@ def test_url(dvc):
     path = "/path/to/dir"
 
     # URL ssh://[user@]host.xz[:port]/path
-    url = "ssh://{}@{}:{}{}".format(user, host, port, path)
+    url = f"ssh://{user}@{host}:{port}{path}"
     config = {"url": url}
 
     remote = SSHRemote(dvc, config)
     assert remote.path_info == url
 
     # SCP-like URL ssh://[user@]host.xz:/absolute/path
-    url = "ssh://{}@{}:{}".format(user, host, path)
+    url = f"ssh://{user}@{host}:{path}"
     config = {"url": url}
 
     remote = SSHRemote(dvc, config)
@@ -60,7 +60,7 @@ else:
 )
 @patch("os.path.exists", return_value=True)
 @patch(
-    "{}.open".format(builtin_module_name),
+    f"{builtin_module_name}.open",
     new_callable=mock_open,
     read_data=mock_ssh_config,
 )
@@ -90,7 +90,7 @@ def test_ssh_host_override_from_config(
 )
 @patch("os.path.exists", return_value=True)
 @patch(
-    "{}.open".format(builtin_module_name),
+    f"{builtin_module_name}.open",
     new_callable=mock_open,
     read_data=mock_ssh_config,
 )
@@ -115,7 +115,7 @@ def test_ssh_user(mock_file, mock_exists, dvc, config, expected_user):
 )
 @patch("os.path.exists", return_value=True)
 @patch(
-    "{}.open".format(builtin_module_name),
+    f"{builtin_module_name}.open",
     new_callable=mock_open,
     read_data=mock_ssh_config,
 )
@@ -150,7 +150,7 @@ def test_ssh_port(mock_file, mock_exists, dvc, config, expected_port):
 )
 @patch("os.path.exists", return_value=True)
 @patch(
-    "{}.open".format(builtin_module_name),
+    f"{builtin_module_name}.open",
     new_callable=mock_open,
     read_data=mock_ssh_config,
 )
@@ -172,7 +172,7 @@ def test_ssh_keyfile(mock_file, mock_exists, dvc, config, expected_keyfile):
 )
 @patch("os.path.exists", return_value=True)
 @patch(
-    "{}.open".format(builtin_module_name),
+    f"{builtin_module_name}.open",
     new_callable=mock_open,
     read_data=mock_ssh_config,
 )

tests/unit/remote/test_azure.py

@@ -23,7 +23,7 @@ def test_init_compat(dvc):
 
 def test_init(dvc):
     prefix = "some/prefix"
-    url = "azure://{}/{}".format(container_name, prefix)
+    url = f"azure://{container_name}/{prefix}"
     config = {"url": url, "connection_string": connection_string}
     remote = AzureRemote(dvc, config)
     assert remote.path_info == url

tests/unit/remote/test_base.py

@@ -7,7 +7,7 @@ from dvc.path_info import PathInfo
 from dvc.remote.base import BaseRemote, RemoteCmdError, RemoteMissingDepsError
 
 
-class _CallableOrNone(object):
+class _CallableOrNone:
     """Helper for testing if object is callable() or None."""
 
     def __eq__(self, other):
@@ -111,11 +111,11 @@ def test_cache_checksums_traverse(path_to_checksum, cache_checksums, dvc):
     list(remote._cache_checksums_traverse(size, {0}))
     for i in range(1, 16):
         cache_checksums.assert_any_call(
-            prefix="{:03x}".format(i), progress_callback=CallableOrNone
+            prefix=f"{i:03x}", progress_callback=CallableOrNone
         )
     for i in range(1, 256):
         cache_checksums.assert_any_call(
-            prefix="{:02x}".format(i), progress_callback=CallableOrNone
+            prefix=f"{i:02x}", progress_callback=CallableOrNone
         )
 
     # default traverse (small remote)

tests/unit/remote/test_gdrive.py

@@ -9,7 +9,7 @@ USER_CREDS_TOKEN_REFRESH_ERROR = '{"access_token": "", "client_id": "", "client_
 USER_CREDS_MISSED_KEY_ERROR = "{}"
 
 
-class TestRemoteGDrive(object):
+class TestRemoteGDrive:
     CONFIG = {
         "url": "gdrive://root/data",
         "gdrive_client_id": "client",

tests/unit/remote/test_gs.py

@@ -6,7 +6,7 @@ from dvc.remote.gs import GSRemote, dynamic_chunk_size
 
 BUCKET = "bucket"
 PREFIX = "prefix"
-URL = "gs://{}/{}".format(BUCKET, PREFIX)
+URL = f"gs://{BUCKET}/{PREFIX}"
 CREDENTIALPATH = "/path/to/gcp_credentials.json"
 PROJECT = "PROJECT"
 CONFIG = {

tests/unit/remote/test_http.py

@@ -8,7 +8,7 @@ from tests.utils.httpd import StaticFileServer
 
 def test_download_fails_on_error_code(dvc):
     with StaticFileServer() as httpd:
-        url = "http://localhost:{}/".format(httpd.server_port)
+        url = f"http://localhost:{httpd.server_port}/"
         config = {"url": url}
 
         remote = HTTPRemote(dvc, config)

tests/unit/remote/test_oss.py

@@ -8,7 +8,7 @@ key_secret = "Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsu"
 
 def test_init(dvc):
     prefix = "some/prefix"
-    url = "oss://{}/{}".format(bucket_name, prefix)
+    url = f"oss://{bucket_name}/{prefix}"
     config = {
         "url": url,
         "oss_key_id": key_id,

tests/unit/remote/test_remote.py

@@ -31,7 +31,7 @@ def test_remote_without_checksum_jobs_default(dvc):
 
 @pytest.mark.parametrize("remote_cls", [GSRemote, S3Remote])
 def test_makedirs_not_create_for_top_level_path(remote_cls, dvc, mocker):
-    url = "{.scheme}://bucket/".format(remote_cls)
+    url = f"{remote_cls.scheme}://bucket/"
     remote = remote_cls(dvc, {"url": url})
     mocked_client = mocker.PropertyMock()
     # we use remote clients with same name as scheme to interact with remote

tests/unit/remote/test_remote_dir.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 import os
 
 import pytest