diff --git a/tests/fixtures/layouts/merging-github.yaml b/tests/fixtures/layouts/merging-github.yaml
index 4e13063..9f43f75 100644
--- a/tests/fixtures/layouts/merging-github.yaml
+++ b/tests/fixtures/layouts/merging-github.yaml
@@ -2,6 +2,7 @@
     name: merge
     description: Pipeline for merging the pull request
     manager: independent
+    merge-failure-message: 'Merge failed'
     trigger:
       github:
         - event: pull_request
diff --git a/tests/unit/test_github_driver.py b/tests/unit/test_github_driver.py
index f287790..c8e7341 100644
--- a/tests/unit/test_github_driver.py
+++ b/tests/unit/test_github_driver.py
@@ -335,6 +335,8 @@
         self.fake_github.emitEvent(D.getCommentAddedEvent('merge me'))
         self.waitUntilSettled()
         self.assertFalse(D.is_merged)
+        self.assertEqual(len(D.comments), 1)
+        self.assertEqual(D.comments[0], 'Merge failed')
 
     @simple_layout('layouts/dependent-github.yaml', driver='github')
     def test_parallel_changes(self):