Add print-message pre-commit hook

tests/print_message_test.py

@@ -0,0 +1,27 @@
+from __future__ import absolute_import
+from __future__ import unicode_literals
+
+from pre_commit_hooks.print_message import default_message
+from pre_commit_hooks.print_message import main
+
+
+def test_passes_by_default():
+    assert main() == 0
+
+
+def test_fails_with_fail_flag():
+    assert main(['-f']) > 0
+    assert main(['--f']) > 0
+
+
+def test_default_message(capsys):
+    main()
+    stdout, _ = capsys.readouterr()
+    assert stdout.strip() == default_message
+
+
+def test_message_argument(capsys):
+    message = 'a message'
+    main(['-m', message])
+    stdout, _ = capsys.readouterr()
+    assert stdout.strip() == message