Fix autoupdate spamming with defaults.

tests/commands_test.py

@@ -120,6 +120,12 @@ def test_out_of_date_repo(out_of_date_repo):
     assert ret['sha'] == out_of_date_repo.head_sha
 
 
+def test_removes_defaults(out_of_date_repo):
+    ret = _update_repository(out_of_date_repo.repo_config)
+    assert 'args' not in ret['hooks'][0]
+    assert 'expected_return_value' not in ret['hooks'][0]
+
+
 def test_autoupdate_out_of_date_repo(out_of_date_repo):
     before = open(C.CONFIG_FILE).read()
     runner = Runner(out_of_date_repo.python_hooks_repo)

tests/jsonschema_extensions_test.py

@@ -1,5 +1,6 @@
 
 from pre_commit.jsonschema_extensions import apply_defaults
+from pre_commit.jsonschema_extensions import remove_defaults
 
 
 def test_apply_defaults_copies_object():
@@ -56,3 +57,25 @@ def test_apply_defaults_copies():
     ret1 = apply_defaults({}, schema)
     ret2 = apply_defaults({}, schema)
     assert ret1['foo'] is not ret2['foo']
+
+
+def test_remove_defaults_copies_object():
+    input = {}
+    ret = remove_defaults(input, {})
+    assert ret is not input
+
+
+def test_remove_defaults_does_not_remove_non_default():
+    ret = remove_defaults(
+        {'foo': 'bar'},
+        {'properties': {'foo': {'default': 'baz'}}},
+    )
+    assert ret == {'foo': 'bar'}
+
+
+def test_remove_defaults_removes_default():
+    ret = remove_defaults(
+        {'foo': 'bar'},
+        {'properties': {'foo': {'default': 'bar'}}},
+    )
+    assert ret == {}