[Telemetry] Allow value interpolation in action_runner JavaScript API

telemetry/telemetry/internal/backends/form_based_credentials_backend_unittest_base.py

 # Copyright 2013 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 telemetry.testing import simple_mock
 
 _ = simple_mock.DONT_CARE
 
 
 class FormBasedCredentialsBackendUnitTestBase(unittest.TestCase):
   def setUp(self):
     self._credentials_type = None
 
   def testLoginUsingMock(self):
     raise NotImplementedError()
 
   def _LoginUsingMock(self, backend, login_page_url, email_element_id,
                       password_element_id, form_element_id,
                       already_logged_in_js): # pylint: disable=no-self-use
+    del form_element_id  # Unused.
     tab = simple_mock.MockObject()
     ar = simple_mock.MockObject()
 
     config = {'username': 'blah',
               'password': 'blargh'}
 
     tab.ExpectCall('Navigate', login_page_url)
     tab.ExpectCall('EvaluateJavaScript', already_logged_in_js).WillReturn(False)
     tab.ExpectCall('WaitForDocumentReadyStateToBeInteractiveOrBetter')
 
-    ar.ExpectCall('WaitForJavaScriptCondition',
-                  '(document.querySelector("#%s") !== null) || (%s)' % (
-                      form_element_id, already_logged_in_js), 60)
+    ar.ExpectCall(
+        'WaitForJavaScriptCondition',
+        '(document.querySelector({{ form_id }}) !== null) || ({{ @code }})')

[perezju, 2017/01/09 13:13:20]

This wasn't a great test to begin with. Looks very much like a "change detection
test" [1]. Ideally should be replaced with a test not using a mock, but this
whole FormBasedCredentials thing seems to be scheduled for deprecation anyway so
I just changed the test enough to make it pass.

[1]:
https://testing.googleblog.com/2015/01/testing-on-toilet-change-detector-test...

     ar.ExpectCall('WaitForNavigate')
 
     def VerifyEmail(js):
       assert email_element_id in js
       assert 'blah' in js
     tab.ExpectCall('ExecuteJavaScript', _).WhenCalled(VerifyEmail)
 
     def VerifyPw(js):
       assert password_element_id in js
       assert 'largh' in js
     tab.ExpectCall('ExecuteJavaScript', _).WhenCalled(VerifyPw)
 
     def VerifySubmit(js):
       assert '.submit' in js or '.click' in js
     tab.ExpectCall('ExecuteJavaScript', _).WhenCalled(VerifySubmit)
 
     # Checking for form still up.
     tab.ExpectCall('EvaluateJavaScript', _).WillReturn(False)
 
     backend.LoginNeeded(tab, ar, config)