[Extern Generation] Add a presubmit script to check externs not being updated

extensions/common/api/externs_checker_test.py

Index: extensions/common/api/externs_checker_test.py
diff --git a/extensions/common/api/externs_checker_test.py b/extensions/common/api/externs_checker_test.py
new file mode 100755
index 0000000000000000000000000000000000000000..c570cdbb18e150ec708cad28245b4c8d52dcd276
--- /dev/null
+++ b/extensions/common/api/externs_checker_test.py
@@ -0,0 +1,76 @@
+#!/usr/bin/env python
+# Copyright 2016 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import unittest
+
+from externs_checker import ExternsChecker
+
+class MockFile(object):

[Dan Beam, 2016/02/23 03:15:24]

use src/PRESUBMIT_test_mocks.py

[Devlin, 2016/02/23 23:12:39]

Hey, look at that!

Done.

+  def __init__(self, path):
+    self.path = path
+  def LocalPath(self):
+    return self.path
+
+class MockWarning(object):
+  def __init__(self, message, items, long_message):
+    self.message = message
+    self.items = items
+    self.long_message = long_message
+
+class MockInputApi(object):
+  def __init__(self, files):
+    self.files = [MockFile(file) for file in files]
+
+  def AffectedFiles(self):
+    return self.files
+
+class MockOutputApi(object):
+  def PresubmitPromptWarning(self, message, items, long_message):
+    return MockWarning(message, items, long_message)
+
+class ExternsCheckerTest(unittest.TestCase):
+  API_PAIRS = {'a': '1', 'b': '2', 'c': '3'}
+
+  def _runChecks(self, files):
+    input_api = MockInputApi(files)
+    output_api = MockOutputApi()
+    checker = ExternsChecker(input_api, output_api, self.API_PAIRS)
+    return checker.RunChecks()
+
+  def testModifiedSourceWithoutModifiedExtern(self):
+    results = self._runChecks(['b', 'test', 'random'])
+    self.assertEquals(1, len(results))
+    self.assertEquals(1, len(results[0].items))
+    self.assertEquals('b', results[0].items[0])
+    self.assertEquals(
+        'To update the externs, run "'
+        'src/ $ python tools/json_schema_compiler/compiler.py b --root=. '
+        '--generator=externs > 2"',
+        results[0].long_message)
+
+  def testModifiedSourceWithModifiedExtern(self):
+    results = self._runChecks(['b', '2', 'test', 'random'])
+    self.assertEquals(0, len(results))
+
+  def testModifiedMultipleSourcesWithNoModifiedExterns(self):
+    results = self._runChecks(['b', 'test', 'c', 'random'])
+    self.assertEquals(1, len(results))
+    self.assertEquals(2, len(results[0].items))
+    self.assertTrue('b' in results[0].items)
+    self.assertTrue('c' in results[0].items)
+    self.assertEquals(
+        'To update the externs, run "'
+        'src/ $ python tools/json_schema_compiler/compiler.py <source_file> '
+        '--root=. --generator=externs > <output_file>"',
+        results[0].long_message)
+
+  def testModifiedMultipleSourcesWithOneModifiedExtern(self):
+    results = self._runChecks(['b', 'test', 'c', 'random', '2'])
+    self.assertEquals(1, len(results))
+    self.assertEquals(1, len(results[0].items))
+    self.assertEquals('c', results[0].items[0])
+
+if __name__ == '__main__':
+  unittest.main()