Fix flaky test_import_timestamp test.

TNL-2386

common/test/acceptance/pages/studio/import_export.py

@@ -239,10 +239,16 @@ class ImportMixin(object):
 
     def is_timestamp_visible(self):
         """
-        Checks if the UTC timestamp of the last successfull import is visible
+        Checks if the UTC timestamp of the last successful import is visible
         """
         return self.q(css='.item-progresspoint-success-date').visible
 
+    def wait_for_timestamp_visible(self):
+        """
+        Wait for the timestamp of the last successful import to be visible.
+        """
+        EmptyPromise(self.is_timestamp_visible, 'Timestamp Visible', timeout=30).fulfill()
+
     def wait_for_filename_error(self):
         """
         Wait for the upload field to display an error.

common/test/acceptance/tests/studio/test_import_export.py

@@ -4,7 +4,6 @@ Acceptance tests for the Import and Export pages
 from abc import abstractmethod
 from bok_choy.promise import EmptyPromise
 from datetime import datetime
-from flaky import flaky
 
 from .base_studio_test import StudioLibraryTest, StudioCourseTest
 from ...fixtures.course import XBlockFixtureDesc
@@ -186,7 +185,6 @@ class ImportTestMixin(object):
         self.import_page.upload_tarball(self.tarball_name)
         self.import_page.wait_for_upload()
 
-    @flaky  # TODO: fix this. See TNL-2386
     def test_import_timestamp(self):
         """
         Scenario: I perform a course / library import
@@ -200,13 +198,13 @@ class ImportTestMixin(object):
         utc_now = datetime.utcnow()
         import_date, import_time = self.import_page.timestamp
 
-        self.assertTrue(self.import_page.is_timestamp_visible())
+        self.import_page.wait_for_timestamp_visible()
         self.assertEqual(utc_now.strftime('%m/%d/%Y'), import_date)
         self.assertEqual(utc_now.strftime('%H:%M'), import_time)
 
         self.import_page.visit()
         self.import_page.wait_for_tasks(completed=True)
-        self.assertTrue(self.import_page.is_timestamp_visible())
+        self.import_page.wait_for_timestamp_visible()
 
     def test_landing_url(self):
         """