Add git-diff argument to directly staged changes

.pre-commit-hooks.yaml

@@ -2,5 +2,6 @@
     name: relint
     description: 'Write your own linting rules using regular expressions.'
     entry: relint
+    args: [--git-diff]
     language: python
     types: [file]

README.rst

@@ -32,36 +32,40 @@ expressions can match multiple lines and include newlines.
 You can narrow down the file types your linter should be working with, by
 providing the optional ``filePattern`` attribute. The default is ``.*``.
 
-The optional `error` attribute allows you to only show a warning but not exit
-with a bad (non-zero) exit code. The default is `true`.
+The optional ``error`` attribute allows you to only show a warning but not exit
+with a bad (non-zero) exit code. The default is ``true``.
 
 The following command will lint all files in the current directory:
 
 .. code-block:: bash
 
     relint -c .relint.yml **
 
-The default configuration file name is `.relint.yml` within your working
+The default configuration file name is ``.relint.yml`` within your working
 directory, but you can provide any YAML or JSON file.
 
 If you prefer linting changed files (cached on git) you can use the option
-`--diff [-d]`:
+``--diff [-d]`` or ``--git-diff [-g]``:
 
 .. code-block:: bash
 
     git diff --unified=0 | relint my_file.py --diff
 
-This option is useful for pre-commit purposes. Here an example of how to use it
+
+pre-commit
+^^^^^^^^^^
+
+You can automate the linting process by adding a **pre-commit** hook to your
+project. Add the following entry to your ``.pre-commit-config.yaml``:
 with `pre-commit`_ framework:
 
 .. code-block:: yaml
 
     - repo: https://github.com/codingjoe/relint
-      rev: 1.2.0
+      rev: 1.4.0
       hooks:
         - id: relint
-
-You can find an example of `relint-pre-commit.sh`_ in this repository.
+          args: [-W]  # optional, if you want to fail on warnings during commit
 
 Samples
 -------
@@ -80,7 +84,7 @@ Samples
 
     - name: the database is lava
       pattern: '@pytest.fixture.*\n[ ]*def [^(]+\([^)]*(db|transactional_db)(, |\))'
-      hint: Please do not create db fixtures but model_bakery recipies instead.
+      hint: Please do not create db fixtures but model_bakery recipes instead.
       filePattern: .*\.py
 
     - name: No logger in management commands

relint.py

@@ -2,6 +2,7 @@
 import fnmatch
 import glob
 import re
+import subprocess
 import sys
 import warnings
 from collections import namedtuple
@@ -58,7 +59,12 @@ def parse_args(args):
         '-d',
         '--diff',
         action='store_true',
-        help='Analyze content from git diff.'
+        help='Analyze content from a diff.'
+    )
+    parser.add_argument(
+        '--git-diff',
+        action='store_true',
+        help='Analyze content from git diff directly by calling `git diff --staged`.'
     )
     parser.add_argument(
         '-W',
@@ -249,6 +255,12 @@ def main(args=sys.argv[1:]):
 
     if args.diff:
         output = sys.stdin.read()
+    elif args.git_diff:
+        output = subprocess.check_output(
+            ['git', 'diff', '--staged', '--unified=0', '--no-color'],
+            universal_newlines=True,
+        )
+    if args.diff or args.git_diff:
         changed_content = parse_diff(output)
         matches = match_with_diff_changes(changed_content, matches)
 

test_relint.py

@@ -1,4 +1,6 @@
 import io
+import os
+import subprocess
 import sys
 import warnings
 
@@ -196,3 +198,14 @@ def test_corrupt_config_file(self, tmpdir):
                 main(['**'])
 
         assert 'Error parsing your relint config file.' in str(exc_info.value)
+
+    def test_git_diff(self, capsys, tmpdir):
+        tmpdir.join('.relint.yml').write(open('.relint.yml').read())
+        tmpdir.join('dummy.py').write("# TODO do something")
+        subprocess.check_call(['git', 'init'], cwd=tmpdir.strpath)  # nosec
+
+        with tmpdir.as_cwd():
+            with pytest.raises(SystemExit) as exc_info:
+                main(['relint.py', 'dummy.py', '--git-diff'])
+
+        assert '0' in str(exc_info.value)