Add a new hook to forbid new submodules
diff --git a/tests/forbid_new_submodules_test.py b/tests/forbid_new_submodules_test.py
new file mode 100644
index 0000000..1750e00
--- /dev/null
+++ b/tests/forbid_new_submodules_test.py
@@ -0,0 +1,39 @@
+from __future__ import absolute_import
+
+import pytest
+from pre_commit.util import cmd_output
+
+from pre_commit_hooks.forbid_new_submodules import main
+
+
+@pytest.yield_fixture
+def git_dir_with_git_dir(tmpdir):
+ with tmpdir.as_cwd():
+ cmd_output('git', 'init', '.')
+ cmd_output('git', 'commit', '-m', 'init', '--allow-empty')
+ cmd_output('git', 'init', 'foo')
+ with tmpdir.join('foo').as_cwd():
+ cmd_output('git', 'commit', '-m', 'init', '--allow-empty')
+ yield
+
+
+@pytest.mark.parametrize(
+ 'cmd',
+ (
+ # Actually add the submodule
+ ('git', 'submodule', 'add', './foo'),
+ # Sneaky submodule add (that doesn't show up in .gitmodules)
+ ('git', 'add', 'foo'),
+ ),
+)
+def test_main_new_submodule(git_dir_with_git_dir, capsys, cmd):
+ cmd_output(*cmd)
+ assert main() == 1
+ out, _ = capsys.readouterr()
+ assert out.startswith('foo: new submodule introduced\n')
+
+
+def test_main_no_new_submodule(git_dir_with_git_dir):
+ open('test.py', 'a+').close()
+ cmd_output('git', 'add', 'test.py')
+ assert main() == 0
