Add update_commit_msg

Update hooks file

Update description

Simplify approach

Remove redundant statement

Add test

Add more tests

Updates lints

Use io.open instead

Update setup.py

Remove unused import

Rename update-commit-msg to prepend-ticket-number-to-commit-msg

tests/prepend_ticket_number_to_commit_msg_test.py

@@ -0,0 +1,53 @@
+from __future__ import absolute_import
+from __future__ import unicode_literals
+
+import mock
+import pytest
+import six
+
+from pre_commit_hooks.prepend_ticket_number_to_commit_msg import get_branch_name
+from pre_commit_hooks.prepend_ticket_number_to_commit_msg import main
+from pre_commit_hooks.prepend_ticket_number_to_commit_msg import update_commit_message
+
+
+TESTING_MODULE = 'pre_commit_hooks.prepend_ticket_number_to_commit_msg'
+
+
+@pytest.mark.parametrize(
+    ('msg'),
+    (
+        'Test',
+        'JIRA-1234_Test',
+    ),
+)
+@mock.patch(TESTING_MODULE + '.get_branch_name')
+def test_update_commit_message(mock_branch_name, msg, tmpdir):
+    mock_branch_name.return_value = 'JIRA-1234_new_feature'
+    path = tmpdir.join('file.txt')
+    path.write(msg)
+    update_commit_message(six.text_type(path), '[A-Z]+-\d+')  # noqa
+    assert 'JIRA-1234' in path.read()
+
+
+@mock.patch(TESTING_MODULE + '.subprocess')
+def test_get_branch_name(mock_subprocess):
+    get_branch_name()
+    mock_subprocess.check_output.assert_called_once_with(
+        [
+            'git',
+            'rev-parse',
+            '--abbrev-ref',
+            'HEAD',
+        ],
+    )
+
+
+@mock.patch(TESTING_MODULE + '.argparse')
+@mock.patch(TESTING_MODULE + '.update_commit_message')
+def test_main(mock_update_commit_message, mock_argparse):
+    mock_args = mock.Mock()
+    mock_args.filenames = ['foo.txt']
+    mock_args.regex = None
+    mock_argparse.ArgumentParser.return_value.parse_args.return_value = mock_args
+    main()
+    mock_update_commit_message.assert_called_once_with('foo.txt', '[A-Z]+-\d+')  # noqa