Add diff logic to python format subcommand (#15156)

* Add diff logic to python format subcommand

* Update test

* Add in filter per format-c

* fix tests

* Update new workflow

2 files changed, 56 insertions, 14 deletions

diff --git a/lib/python/qmk/cli/format/python.py b/lib/python/qmk/cli/format/python.py
index 00612f97e..95868d18a 100755
--- a/lib/python/qmk/cli/format/python.py
+++ b/lib/python/qmk/cli/format/python.py
@@ -4,23 +4,65 @@ from subprocess import CalledProcessError, DEVNULL
 
 from milc import cli
 
+from qmk.path import normpath
 
-@cli.argument('-n', '--dry-run', arg_only=True, action='store_true', help="Don't actually format.")
-@cli.subcommand("Format python code according to QMK's style.", hidden=False if cli.config.user.developer else True)
-def format_python(cli):
-    """Format python code according to QMK's style.
-    """
+py_file_suffixes = ('py',)
+py_dirs = ['lib/python']
+
+
+def yapf_run(files):
     edit = '--diff' if cli.args.dry_run else '--in-place'
-    yapf_cmd = ['yapf', '-vv', '--recursive', edit, 'bin/qmk', 'lib/python']
+    yapf_cmd = ['yapf', '-vv', '--recursive', edit, *files]
     try:
         cli.run(yapf_cmd, check=True, capture_output=False, stdin=DEVNULL)
-        cli.log.info('Python code in `bin/qmk` and `lib/python` is correctly formatted.')
-        return True
+        cli.log.info('Successfully formatted the python code.')
 
     except CalledProcessError:
-        if cli.args.dry_run:
-            cli.log.error('Python code in `bin/qmk` and `lib/python` incorrectly formatted!')
+        cli.log.error(f'Python code in {",".join(py_dirs)} incorrectly formatted!')
+        return False
+
+
+def filter_files(files):
+    """Yield only files to be formatted and skip the rest
+    """
+
+    for file in files:
+        if file and file.name.split('.')[-1] in py_file_suffixes:
+            yield file
         else:
-            cli.log.error('Error formatting python code!')
+            cli.log.debug('Skipping file %s', file)
+
+
+@cli.argument('-n', '--dry-run', arg_only=True, action='store_true', help="Don't actually format.")
+@cli.argument('-b', '--base-branch', default='origin/master', help='Branch to compare to diffs to.')
+@cli.argument('-a', '--all-files', arg_only=True, action='store_true', help='Format all files.')
+@cli.argument('files', nargs='*', arg_only=True, type=normpath, help='Filename(s) to format.')
+@cli.subcommand("Format python code according to QMK's style.", hidden=False if cli.config.user.developer else True)
+def format_python(cli):
+    """Format python code according to QMK's style.
+    """
+    # Find the list of files to format
+    if cli.args.files:
+        files = list(filter_files(cli.args.files))
+
+        if not files:
+            cli.log.error('No Python files in filelist: %s', ', '.join(map(str, cli.args.files)))
+            exit(0)
+
+        if cli.args.all_files:
+            cli.log.warning('Filenames passed with -a, only formatting: %s', ','.join(map(str, files)))
+
+    elif cli.args.all_files:
+        files = py_dirs
+
+    else:
+        git_diff_cmd = ['git', 'diff', '--name-only', cli.args.base_branch, *py_dirs]
+        git_diff = cli.run(git_diff_cmd, stdin=DEVNULL)
+        files = list(filter(None, git_diff.stdout.split('\n')))
+
+    # Sanity check
+    if not files:
+        cli.log.error('No changed files detected. Use "qmk format-python -a" to format all files')
+        return False
 
-    return False
+    return yapf_run(files)
diff --git a/lib/python/qmk/tests/test_cli_commands.py b/lib/python/qmk/tests/test_cli_commands.py
index b39fe5e46..0dad5d5fc 100644
--- a/lib/python/qmk/tests/test_cli_commands.py
+++ b/lib/python/qmk/tests/test_cli_commands.py
@@ -81,9 +81,9 @@ def test_hello():
 
 
 def test_format_python():
-    result = check_subcommand('format-python', '--dry-run')
+    result = check_subcommand('format-python', '-n', '-a')
     check_returncode(result)
-    assert 'Python code in `bin/qmk` and `lib/python` is correctly formatted.' in result.stdout
+    assert 'Successfully formatted the python code.' in result.stdout
 
 
 def test_list_keyboards():