vcs/git: Add GitIgnoreBear

Closes #2610

bears/vcs/git/GitIgnoreBear.py

@@ -0,0 +1,50 @@
+import shutil
+
+from coalib.bears.GlobalBear import GlobalBear
+from coalib.misc.Shell import run_shell_command
+
+
+class GitIgnoreBear(GlobalBear):
+    AUTHORS = {'The coala developers'}
+    AUTHORS_EMAILS = {'[email protected]'}
+    LICENSE = 'AGPL-3.0'
+    CAN_DETECT = {'Formatting'}
+    LANGUAGES = {'Git'}
+
+    @classmethod
+    def check_prerequisites(cls):
+        if shutil.which('git') is None:
+            return 'git is not installed.'
+        else:
+            return True
+
+    @staticmethod
+    def get_ignored_files():
+        """
+        This function checks for the files that are being tracked
+        but are ignored in .gitignore file.
+        Visit https://github.com/coala/coala-bears/issues/2610
+        for more details.
+
+        :return:
+            A list of details of tracked files that are
+            ignored in .gitignore file.
+        """
+        files, _ = run_shell_command('git ls-files')
+        files = files.strip().split('\n')
+        ignored = list(map(
+            lambda file: run_shell_command(
+                'git check-ignore --no-index -v {}'.format(file))[0].strip(),
+            files
+        ))
+        return list(filter(lambda f: f != '', ignored))
+
+    def run(self):
+        for line in GitIgnoreBear.get_ignored_files():
+            pattern, filename = line.split('\t')
+            ignore_filename, line_number, ignore_regex = pattern.split(':')
+            yield self.new_result(
+                message='File {} is being tracked which was ignored in line '
+                        'number {} in file {}.'.format(
+                            filename, line_number, ignore_filename),
+                file=filename)

tests/vcs/git/GitIgnoreBearTest.py

@@ -0,0 +1,119 @@
+import os
+import platform
+import shutil
+import stat
+import unittest
+import unittest.mock
+from queue import Queue
+from tempfile import mkdtemp
+
+from bears.vcs.git.GitIgnoreBear import GitIgnoreBear
+from coalib.testing.BearTestHelper import generate_skip_decorator
+from coalib.misc.Shell import run_shell_command
+from coalib.settings.Section import Section
+
+
+@generate_skip_decorator(GitIgnoreBear)
+class GitIgnoreBearTest(unittest.TestCase):
+
+    @staticmethod
+    def run_git_command(*args, stdin=None):
+        run_shell_command(' '.join(('git',) + args), stdin)
+
+    def run_uut(self, *args, **kwargs):
+        """
+        Runs the unit-under-test (via `self.uut.run()`) and collects the
+        messages of the yielded results as a list.
+
+        :param args:   Positional arguments to forward to the run function.
+        :param kwargs: Keyword arguments to forward to the run function.
+        :return:       A list of the message strings.
+        """
+        return list(result.message for result in self.uut.run(*args, **kwargs))
+
+    def assert_no_msgs(self):
+        """
+        Assert that there are no messages in the message queue of the bear, and
+        show the messages in the failure message if it is not empty.
+        """
+        self.assertTrue(
+            self.msg_queue.empty(),
+            'Expected no messages in bear message queue, but got: ' +
+            str(list(str(i) for i in self.msg_queue.queue)))
+
+    def setUp(self):
+        self.msg_queue = Queue()
+        self.section = Section('')
+        self.uut = GitIgnoreBear(None, self.section, self.msg_queue)
+
+        self._old_cwd = os.getcwd()
+        self.gitdir = mkdtemp()
+        os.chdir(self.gitdir)
+        self.run_git_command('init')
+        self.run_git_command('config', 'user.email [email protected]')
+        self.run_git_command('config', 'user.name coala')
+
+    @staticmethod
+    def _windows_rmtree_remove_readonly(func, path, excinfo):
+        os.chmod(path, stat.S_IWRITE)
+        func(path)
+
+    def tearDown(self):
+        os.chdir(self._old_cwd)
+        if platform.system() == 'Windows':
+            onerror = self._windows_rmtree_remove_readonly
+        else:
+            onerror = None
+        shutil.rmtree(self.gitdir, onerror=onerror)
+
+    def test_check_prerequisites(self):
+        _shutil_which = shutil.which
+        try:
+            shutil.which = lambda *args, **kwargs: None
+            self.assertEqual(GitIgnoreBear.check_prerequisites(),
+                             'git is not installed.')
+
+            shutil.which = lambda *args, **kwargs: 'path/to/git'
+            self.assertTrue(GitIgnoreBear.check_prerequisites())
+        finally:
+            shutil.which = _shutil_which
+
+    def test_no_tracked_files(self):
+        self.assertEqual(self.run_uut(), [])
+        self.assert_no_msgs()
+
+    def test_no_gitignore_file(self):
+        file = open('test_file.txt', 'w')
+        file.close()
+        self.run_git_command('add', 'test_file.txt')
+
+        self.assertEqual(self.run_uut(), [])
+        self.assert_no_msgs()
+
+    def test_already_tracked_file(self):
+        file = open('test_file.txt', 'w')
+        file.close()
+        self.run_git_command('add', 'test_file.txt')
+
+        file = open('.gitignore', 'w')
+        file.write('test_file.txt')
+        file.close()
+
+        self.run_git_command('add', '.gitignore')
+        self.assertEqual(self.run_uut(), [
+            'File test_file.txt is being tracked which was ignored in line'
+            ' number 1 in file .gitignore.'
+        ])
+        self.assert_no_msgs()
+
+    def test_untracked_file(self):
+        file = open('test_file.txt', 'w')
+        file.close()
+
+        file = open('.gitignore', 'w')
+        file.write('test_file.txt')
+        file.close()
+
+        self.run_git_command('add', '.gitignore')
+        self.assertEqual(self.run_uut(), [])
+        self.assert_no_msgs()