Merge pull request #1400 from diseraluca/issue/1397

Extends git_hook to allow for a user-specified configuration file.

README.md

@@ -556,7 +556,7 @@ include the following in `.git/hooks/pre-commit`:
 import sys
 from isort.hooks import git_hook
 
-sys.exit(git_hook(strict=True, modify=True, lazy=True))
+sys.exit(git_hook(strict=True, modify=True, lazy=True, settings_file=""))
 ```
 
 If you just want to display warnings, but allow the commit to happen
@@ -569,6 +569,15 @@ Set it to `True` to ensure all tracked files are properly isorted,
 leave it out or set it to `False` to check only files added to your
 index.
 
+If you want to use a specific configuration file for the hook, you can pass its
+path to settings_file. If no path is specifically requested, `git_hook` will
+search for the configuration file starting at the directory containing the first
+staged file, as per `git diff-index` ordering, and going upward in the directory
+structure until a valid configuration file is found or
+[`MAX_CONFIG_SEARCH_DEPTH`](src/config.py:35) directories are checked.
+The settings_file parameter is used to support users who keep their configuration
+file in a directory that might not be a parent of all the other files.
+
 ## Setuptools integration
 
 Upon installation, isort enables a `setuptools` command that checks

isort/hooks.py

@@ -33,7 +33,9 @@ def get_lines(command: List[str]) -> List[str]:
     return [line.strip() for line in stdout.splitlines()]
 
 
-def git_hook(strict: bool = False, modify: bool = False, lazy: bool = False) -> int:
+def git_hook(
+    strict: bool = False, modify: bool = False, lazy: bool = False, settings_file: str = ""
+) -> int:
     """
     Git pre-commit hook to check staged files for isort errors
 
@@ -46,6 +48,11 @@ def git_hook(strict: bool = False, modify: bool = False, lazy: bool = False) ->
     :param bool lazy - if True, also check/fix unstaged files.
         This is useful if you frequently use ``git commit -a`` for example.
         If False, ony check/fix the staged files for isort errors.
+    :param str settings_file - A path to a file to be used as
+                               the configuration file for this run.
+        When settings_file is the empty string, the configuration file
+        will be searched starting at the directory containing the first
+        staged file, if any, and going upward in the directory structure.
 
     :return number of errors if in strict mode, 0 otherwise.
     """
@@ -60,7 +67,10 @@ def git_hook(strict: bool = False, modify: bool = False, lazy: bool = False) ->
         return 0
 
     errors = 0
-    config = Config(settings_path=os.path.dirname(os.path.abspath(files_modified[0])))
+    config = Config(
+        settings_file=settings_file,
+        settings_path=os.path.dirname(os.path.abspath(files_modified[0])),
+    )
     for filename in files_modified:
         if filename.endswith(".py"):
             # Get the staged contents of the file

tests/test_hooks.py

@@ -1,4 +1,5 @@
 import os
+from pathlib import Path
 from unittest.mock import MagicMock, patch
 
 from isort import exceptions, hooks
@@ -53,3 +54,31 @@ class FakeProcessResponse(object):
         with patch("subprocess.run", MagicMock(return_value=FakeProcessResponse())) as run_mock:
             with patch("isort.api", MagicMock(side_effect=exceptions.FileSkipped("", ""))):
                 hooks.git_hook(modify=True)
+
+
+def test_git_hook_uses_the_configuration_file_specified_in_settings_path(tmp_path: Path) -> None:
+    subdirectory_path = tmp_path / "subdirectory"
+    configuration_file_path = subdirectory_path / ".isort.cfg"
+
+    # Inserting the modified file in the parent directory of the configuration file ensures that it
+    # will not be found by the normal search routine
+    modified_file_path = configuration_file_path.parent.parent / "somefile.py"
+
+    # This section will be used to check that the configuration file was indeed loaded
+    section = "testsection"
+
+    os.mkdir(subdirectory_path)
+    with open(configuration_file_path, "w") as fd:
+        fd.write("[isort]\n")
+        fd.write(f"sections={section}")
+
+    with open(modified_file_path, "w") as fd:
+        pass
+
+    files_modified = [str(modified_file_path.absolute())]
+    with patch("isort.hooks.get_lines", MagicMock(return_value=files_modified)):
+        with patch("isort.hooks.get_output", MagicMock(return_value="")):
+            with patch("isort.api.check_code_string", MagicMock()) as run_mock:
+                hooks.git_hook(settings_file=str(configuration_file_path))
+
+                assert run_mock.call_args[1]["config"].sections == (section,)