js_checker.py: Restore smoke tests for linting violations.

tools/web_dev_style/js_checker_eslint_test.py

Index: tools/web_dev_style/js_checker_eslint_test.py
diff --git a/tools/web_dev_style/js_checker_eslint_test.py b/tools/web_dev_style/js_checker_eslint_test.py
new file mode 100755
index 0000000000000000000000000000000000000000..dd6f54a7e0fe9e3a32305b46b07d14e262eb5f15
--- /dev/null
+++ b/tools/web_dev_style/js_checker_eslint_test.py
@@ -0,0 +1,60 @@
+#!/usr/bin/env python
+# Copyright 2017 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 js_checker
+import os
+import shutil
+import sys
+import tempfile
+import unittest
+import json
+
+sys.path.append(
+        os.path.join(os.path.dirname(os.path.abspath(__file__)), '..', '..'))
+
+from PRESUBMIT_test_mocks import (MockInputApi, MockOutputApi, MockFile,
+                                  MockChange)
+
+class JsCheckerEsLintTest(unittest.TestCase):
+  def setUp(self):
+    self._tmp_files = []
+
+    input_api = MockInputApi()
+    output_api = MockOutputApi()
+    self.checker = js_checker.JSChecker(input_api, output_api)
+
+
+  def tearDown(self):
+    for tmp_file in self._tmp_files:
+      os.remove(tmp_file)
+
+
+  def _create_tmp_file(self, file_contents):
+    # Temp files need to be under src/ such that src/.eslintrc.js takes effect.
+    _HERE_PATH = os.path.dirname(__file__)
+    with open(os.path.join(_HERE_PATH, 'tmp_eslint_test.js'), 'w') as f:
+      self._tmp_files.append(f.name)
+      f.write(file_contents)
+    return f
+
+
+  def testGetElementByIdCheck(self):
+    checker = js_checker.JSChecker(MockInputApi(), MockOutputApi())
+    tmp = self._create_tmp_file('var a = document.getElementById(\'foo\');')
+
+    resultsJson = checker.RunEsLintChecks([tmp.name], format='json')
+    self.assertEqual(1, len(resultsJson))
+
+    results = json.loads(resultsJson[0].message)
+    self.assertEqual(1, len(results))
+
+    self.assertEqual(1, len(results[0].get('messages')))
+    message = results[0].get('messages')[0]
+    self.assertEqual('no-restricted-properties', message.get('ruleId'))
+    self.assertEqual(1, message.get('line'))
+
+
+if __name__ == '__main__':
+  unittest.main()