Add check_rubocop

Uses rubocop to check syntax / style of ruby files.

README.md

@@ -34,6 +34,7 @@ Add this to your `.pre-commit-config.yaml`
 - `check-docstring-first` - Checks for a common error of placing code before
   the docstring.
 - `check-json` - Attempts to load all json files to verify syntax.
+- `check-rubocop` - Attempts to verify syntax / style for ruby files
 - `check-merge-conflict` - Check for files that contain merge conflict strings.
 - `check-xml` - Attempts to load all xml files to verify syntax.
 - `check-yaml` - Attempts to load all yaml files to verify syntax.

hooks.yaml

@@ -37,6 +37,12 @@
     entry: check-json
     language: python
     files: \.json$
+-   id: check-rubocop
+    name: Check Rubocop
+    description: This hook checks ruby files for syntax/style
+    entry: check-rubocop
+    language: python
+    files: \.rb$
 -   id: pretty-format-json
     name: Pretty format JSON
     description: This hook sets a standard for formatting JSON files.

pre_commit_hooks/check_rubocop.py

@@ -0,0 +1,27 @@
+from __future__ import print_function
+
+import argparse
+import subprocess
+import sys
+
+
+def check_rubocop(argv=None):
+    parser = argparse.ArgumentParser()
+    parser.add_argument('filenames', nargs='*', help='filenames to check.')
+    args = parser.parse_args(argv)
+
+    retval = 0
+
+    command = ["rubocop"] + args.filenames
+
+    try:
+        retval = subprocess.check_call(command, shell=False)
+    except subprocess.CalledProcessError as err:
+        print('{0}: rubocop failed ({1})'.format(args.filenames, err))
+        retval = 1
+
+    return retval
+
+
+if __name__ == '__main__':
+    sys.exit(check_rubocop())

setup.py

@@ -42,6 +42,7 @@ setup(
             'check-case-conflict = pre_commit_hooks.check_case_conflict:main',
             'check-docstring-first = pre_commit_hooks.check_docstring_first:main',
             'check-json = pre_commit_hooks.check_json:check_json',
+            'check-rubocop = pre_commit_hooks.check_rubocop:check_rubocop',
             'check-merge-conflict = pre_commit_hooks.check_merge_conflict:detect_merge_conflict',
             'check-xml = pre_commit_hooks.check_xml:check_xml',
             'check-yaml = pre_commit_hooks.check_yaml:check_yaml',

testing/resources/invalid_ruby.rb

@@ -0,0 +1 @@
+puts 'Hello World!

testing/resources/valid_ruby.rb

@@ -0,0 +1 @@
+puts 'Hello World!'

tests/check_rubocop_test.py

@@ -0,0 +1,13 @@
+import pytest
+
+from pre_commit_hooks.check_rubocop import check_rubocop
+from testing.util import get_resource_path
+
+
+@pytest.mark.parametrize(('filename', 'expected_retval'), (
+    ('invalid_ruby.rb', 1),
+    ('valid_ruby.rb', 0),
+))
+def test_check_rubocop(filename, expected_retval):
+    ret = check_rubocop([get_resource_path(filename)])
+    assert ret == expected_retval