Bug 1488468 - Remove wait.until calls and improve formatting in test_main_tab_scalar; r=davehunt

Depends on D7904

Differential Revision: https://phabricator.services.mozilla.com/D7905

--HG--
extra : moz-landing-system : lando

toolkit/components/telemetry/tests/marionette/tests/client/test_main_tab_scalars.py

@@ -2,34 +2,46 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-from marionette_driver.wait import Wait
-
 from telemetry_harness.testcase import TelemetryTestCase
 
 
+def check_is_shutdown_ping(ping):
+    """Check for a shutdown ping."""
+
+    if ping["type"] != "main":
+        return False
+
+    if ping["payload"]["info"]["reason"] != "shutdown":
+        return False
+
+    return True
+
+
 class TestMainTabScalars(TelemetryTestCase):
+    """Tests for Telemetry Scalars."""
 
     def test_main_tab_scalars(self):
-        wait = Wait(self.marionette, 10)
+        """Test for Telemetry Scalars."""
 
         with self.marionette.using_context(self.marionette.CONTEXT_CHROME):
             tab1 = self.browser.tabbar.selected_tab
+
             tab2 = self.browser.tabbar.open_tab()
-            wait.until(lambda m: len(self.browser.tabbar.tabs) == 2)
             self.browser.tabbar.switch_to(tab2)
+
             tab3 = self.browser.tabbar.open_tab()
-            wait.until(lambda m: len(self.browser.tabbar.tabs) == 3)
             self.browser.tabbar.switch_to(tab3)
+
             self.browser.tabbar.close_tab(tab3, force=True)
-            wait.until(lambda m: len(self.browser.tabbar.tabs) == 2)
             self.browser.tabbar.close_tab(tab2, force=True)
-            wait.until(lambda m: len(self.browser.tabbar.tabs) == 1)
+
             self.browser.tabbar.switch_to(tab1)
-        ping = self.wait_for_ping(self.restart_browser, lambda p: p['type'] == 'main'
-                                  and p['payload']['info']['reason'] == 'shutdown')
-        assert ping['type'] == 'main'
-        assert ping['clientId'] == self.client_id
-        scalars = ping['payload']['processes']['parent']['scalars']
-        assert scalars['browser.engagement.max_concurrent_tab_count'] == 3
-        assert scalars['browser.engagement.tab_open_event_count'] == 2
-        assert scalars['browser.engagement.max_concurrent_window_count'] == 1
+
+        ping = self.wait_for_ping(self.restart_browser, check_is_shutdown_ping)
+        assert ping["type"] == "main"
+        assert ping["clientId"] == self.client_id
+
+        scalars = ping["payload"]["processes"]["parent"]["scalars"]
+        assert scalars["browser.engagement.max_concurrent_tab_count"] == 3
+        assert scalars["browser.engagement.tab_open_event_count"] == 2
+        assert scalars["browser.engagement.max_concurrent_window_count"] == 1