[Telemetry] Allow value interpolation in action_runner JavaScript API

telemetry/telemetry/internal/backends/form_based_credentials_backend_unittest_base.py

Index: telemetry/telemetry/internal/backends/form_based_credentials_backend_unittest_base.py
diff --git a/telemetry/telemetry/internal/backends/form_based_credentials_backend_unittest_base.py b/telemetry/telemetry/internal/backends/form_based_credentials_backend_unittest_base.py
index 8752c06370f203a401ec599856b2596e956250f3..437689b516a5576b2ccd91bffb7559774cd24907 100644
--- a/telemetry/telemetry/internal/backends/form_based_credentials_backend_unittest_base.py
+++ b/telemetry/telemetry/internal/backends/form_based_credentials_backend_unittest_base.py
@@ -19,6 +19,7 @@ class FormBasedCredentialsBackendUnitTestBase(unittest.TestCase):
   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()
 
@@ -29,9 +30,9 @@ class FormBasedCredentialsBackendUnitTestBase(unittest.TestCase):
     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):