diff --git a/tests/test_harness_dispatch.py b/tests/test_harness_dispatch.py
index b61bdef..13a9f40 100644
--- a/tests/test_harness_dispatch.py
+++ b/tests/test_harness_dispatch.py
@@ -123,6 +123,7 @@ def __init__(self, claimed=(), ci=(True,)):
             [],
             [],
         )
+        self.auto_merge_disabled = []
 
     def remote_branch_exists(self, branch):
         return branch in self.claimed
@@ -146,6 +147,10 @@ def comment(self, pr, body, label=None):
     def add_label(self, pr, label):
         self.labels.append((pr, label))
 
+    def disable_auto_merge(self, pr):
+        self.auto_merge_disabled.append(pr)
+        return True
+
     def create_issue(self, title, body, labels):
         self.issues.append((title, body, labels))