list: add --show-json option (#5888)

* list: add --show-json option

* list: add test for --show-json

dvc/command/ls/__init__.py

@@ -34,7 +34,11 @@ class CmdList(CmdBaseNoRepo):
                 recursive=self.args.recursive,
                 dvc_only=self.args.dvc_only,
             )
-            if entries:
+            if self.args.show_json:
+                import json
+
+                logger.info(json.dumps(entries))
+            elif entries:
                 entries = _prettify(entries, sys.stdout.isatty())
                 logger.info("\n".join(entries))
             return 0
@@ -65,6 +69,9 @@ def add_parser(subparsers, parent_parser):
     list_parser.add_argument(
         "--dvc-only", action="store_true", help="Show only DVC outputs."
     )
+    list_parser.add_argument(
+        "--show-json", action="store_true", help="Show output in JSON format."
+    )
     list_parser.add_argument(
         "--rev",
         nargs="?",

tests/unit/command/ls/test_ls.py

@@ -1,3 +1,6 @@
+import json
+import logging
+
 from dvc.cli import parse_args
 from dvc.command.ls import CmdList
 
@@ -52,3 +55,18 @@ def test_list_outputs_only(mocker):
     m.assert_called_once_with(
         url, None, recursive=False, rev=None, dvc_only=True
     )
+
+
+def test_show_json(mocker, caplog):
+    cli_args = parse_args(["list", "local_dir", "--show-json"])
+    assert cli_args.func == CmdList
+
+    cmd = cli_args.func(cli_args)
+
+    result = [{"key": "val"}]
+    mocker.patch("dvc.repo.Repo.ls", return_value=result)
+
+    with caplog.at_level(logging.INFO, "dvc"):
+        assert cmd.run() == 0
+
+    assert json.dumps(result) in caplog.messages