1 files changed, 11 insertions, 0 deletions
diff --git a/toolkit/components/cleardata/tests/marionette/test_moved_origin_directory_cleanup.py b/toolkit/components/cleardata/tests/marionette/test_moved_origin_directory_cleanup.py
index 876f86cd32..50f4c93f65 100644
--- a/toolkit/components/cleardata/tests/marionette/test_moved_origin_directory_cleanup.py
+++ b/toolkit/components/cleardata/tests/marionette/test_moved_origin_directory_cleanup.py
@@ -46,6 +46,11 @@ class MovedOriginDirectoryCleanupTestCase(MarionetteTestCase):
                 """
             )
 
+    def read_prefs_file(self):
+        pref_path = Path(self.marionette.profile_path) / "prefs.js"
+        with open(pref_path) as f:
+            return f.read()
+
     def removeAllCookies(self):
         with self.marionette.using_context("chrome"):
             self.marionette.execute_script(
@@ -83,6 +88,12 @@ class MovedOriginDirectoryCleanupTestCase(MarionetteTestCase):
             message="privacy.sanitize.pending must include offlineApps",
         )
 
+        # Make sure the pref is written to the file
+        Wait(self.marionette).until(
+            lambda _: "offlineApps" in self.read_prefs_file(),
+            message="prefs.js must include offlineApps",
+        )
+
         # Cleanup happens via Sanitizer.onStartup after restart
         self.marionette.restart(in_app=False)