Add some tests for tests_should_end_in_test hook

tests/conftest.py

@@ -0,0 +1,11 @@
+
+import __builtin__
+
+import mock
+import pytest
+
+
+@pytest.yield_fixture
+def print_mock():
+    with mock.patch.object(__builtin__, 'print', autospec=True) as mock_print:
+        yield mock_print

tests/tests_should_end_in_test_test.py

@@ -0,0 +1,14 @@
+
+from pre_commit_hooks.tests_should_end_in_test import validate_files
+
+
+def test_validate_files_all_pass(print_mock):
+    ret = validate_files(['foo_test.py', 'bar_test.py'])
+    assert ret == 0
+    assert print_mock.call_count == 0
+
+
+def test_validate_files_one_fails(print_mock):
+    ret = validate_files(['not_test_ending.py', 'foo_test.py'])
+    assert ret == 1
+    assert print_mock.call_count == 1