Implemented #1511: Support for easily seeing all files isort will be ran againstissue/1511/show-files-via-cli-support

3 files changed, 37 insertions, 4 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 87baa08a..712e554d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ Find out more about isort's release policy [here](https://pycqa.github.io/isort/
   - Implemented #1433: Provide helpful feedback in case a custom config file is specified without a configuration.
   - Implemented #1494: Default to sorting imports within `.pxd` files.
   - Implemented #1502: Improved float-to-top behavior when there is an existing import section present at top-of-file.
+  - Implemented #1511: Support for easily seeing all files isort will be ran against using `isort . --show-files`.
   - Improved handling of unsupported configuration option errors (see #1475).
   - Fixed #1463: Better interactive documentation for future option.
   - Fixed #1461: Quiet config option not respected by file API in some circumstances.
diff --git a/isort/main.py b/isort/main.py
index fb5f3200..c518a92d 100644
--- a/isort/main.py
+++ b/isort/main.py
@@ -639,6 +639,12 @@ def _build_arg_parser() -> argparse.ArgumentParser:
         help="See isort's determined config, as well as sources of config options.",
     )
     parser.add_argument(
+        "--show-files",
+        dest="show_files",
+        action="store_true",
+        help="See the files isort will be ran against with the current config options.",
+    )
+    parser.add_argument(
         "--honor-noqa",
         dest="honor_noqa",
         action="store_true",
@@ -805,6 +811,9 @@ def main(argv: Optional[Sequence[str]] = None, stdin: Optional[TextIOWrapper] =
         return
 
     show_config: bool = arguments.pop("show_config", False)
+    show_files: bool = arguments.pop("show_files", False)
+    if show_config and show_files:
+        sys.exit("Error: either specify show-config or show-files not both.")
 
     if "settings_path" in arguments:
         if os.path.isfile(arguments["settings_path"]):
@@ -854,6 +863,9 @@ def main(argv: Optional[Sequence[str]] = None, stdin: Optional[TextIOWrapper] =
         print(json.dumps(config.__dict__, indent=4, separators=(",", ": "), default=_preconvert))
         return
     elif file_names == ["-"]:
+        if show_files:
+            sys.exit("Error: can't show files for streaming input.")
+
         if check:
             incorrectly_sorted = not api.check_stream(
                 input_stream=sys.stdin if stdin is None else stdin,
@@ -883,6 +895,10 @@ def main(argv: Optional[Sequence[str]] = None, stdin: Optional[TextIOWrapper] =
             file_names = filtered_files
 
         file_names = iter_source_code(file_names, config, skipped, broken)
+        if show_files:
+            for file_name in file_names:
+                print(file_name)
+            return
         num_skipped = 0
         num_broken = 0
         if config.verbose:
diff --git a/tests/unit/test_main.py b/tests/unit/test_main.py
index ddca98dd..ef837b61 100644
--- a/tests/unit/test_main.py
+++ b/tests/unit/test_main.py
@@ -13,9 +13,6 @@ from isort.exceptions import InvalidSettingsPath
 from isort.settings import DEFAULT_CONFIG, Config
 from isort.wrap_modes import WrapModes
 
-# This test code was written by the `hypothesis.extra.ghostwriter` module
-# and is provided under the Creative Commons Zero public domain dedication.
-
 
 @given(
     file_name=st.text(),
@@ -104,6 +101,26 @@ def test_preconvert():
         main._preconvert(datetime.now())
 
 
+def test_show_files(capsys, tmpdir):
+    tmpdir.join("a.py").write("import a")
+    tmpdir.join("b.py").write("import b")
+
+    # show files should list the files isort would sort
+    main.main([str(tmpdir), "--show-files"])
+    out, error = capsys.readouterr()
+    assert "a.py" in out
+    assert "b.py" in out
+    assert not error
+
+    # can not be used for stream
+    with pytest.raises(SystemExit):
+        main.main(["-", "--show-files"])
+
+    # can not be used with show-config
+    with pytest.raises(SystemExit):
+        main.main([str(tmpdir), "--show-files", "--show-config"])
+
+
 def test_main(capsys, tmpdir):
     base_args = [
         "-sp",
@@ -661,7 +678,6 @@ from a import b, e, c
     )
 
     # ensures that isort warns with deprecated flags with stdin
-
     input_content = TextIOWrapper(
         BytesIO(
             b"""