checkout: Suggest git checkout when dcv checkout fails (#1580)

dvc/project.py

@@ -566,10 +566,20 @@ class Project(object):
     def checkout(
         self, target=None, with_deps=False, force=False, recursive=False
     ):
-
         if target and not recursive:
+            from dvc.stage import (
+                StageFileDoesNotExistError,
+                StageFileBadNameError,
+            )
+
             all_stages = self.active_stages()
-            stages = self._collect(target, with_deps=with_deps)
+            try:
+                stages = self._collect(target, with_deps=with_deps)
+            except (StageFileDoesNotExistError, StageFileBadNameError) as exc:
+                raise DvcException(
+                    str(exc)
+                    + " Did you mean 'git checkout {}'?".format(target)
+                )
         else:
             all_stages = self.active_stages(target)
             stages = all_stages

dvc/stage.py

@@ -415,7 +415,7 @@ class Stage(object):
         if not Stage.is_valid_filename(fname):
             raise StageFileBadNameError(
                 "bad stage filename '{}'. Stage files should be named"
-                " 'Dvcfile' or have a '.dvc' suffix(e.g. '{}.dvc').".format(
+                " 'Dvcfile' or have a '.dvc' suffix (e.g. '{}.dvc').".format(
                     os.path.relpath(fname), os.path.basename(fname)
                 )
             )

tests/test_checkout.py

@@ -370,3 +370,32 @@ class TestCheckoutHook(TestDvc):
 
         with self.assertRaises(ConfirmRemoveError):
             self.dvc.checkout()
+
+
+class TestCheckoutSuggestGit(TestRepro):
+    def test(self):
+
+        try:
+            self.dvc.checkout(target="gitbranch")
+        except DvcException as exc:
+            msg = str(exc)
+            self.assertEqual(
+                msg,
+                "'gitbranch' does not exist. Did you mean 'git checkout gitbranch'?",
+            )
+
+        try:
+            self.dvc.checkout(target=self.FOO)
+        except DvcException as exc:
+            msg = str(exc)
+            self.assertEqual(
+                msg,
+                (
+                    "bad stage filename '{}'."
+                    " Stage files should be named 'Dvcfile'"
+                    " or have a '.dvc' suffix (e.g. '{}.dvc')."
+                    " Did you mean 'git checkout {}'?".format(
+                        self.FOO, self.FOO, self.FOO
+                    )
+                ),
+            )

tests/unit/stage.py

@@ -1,6 +1,5 @@
 import mock
 from unittest import TestCase
-
 from dvc.stage import Stage