diff --git a/ci/build_test_suites_test.py b/ci/build_test_suites_test.py
index c7cd4ab..26f4316 100644
--- a/ci/build_test_suites_test.py
+++ b/ci/build_test_suites_test.py
@@ -38,6 +38,7 @@
 import optimized_targets
 from pyfakefs import fake_filesystem_unittest
 import metrics_agent
+import test_discovery_agent
 
 
 class BuildTestSuitesTest(fake_filesystem_unittest.TestCase):
@@ -261,6 +262,12 @@
     def get_enabled_flag(self):
       return f'{self.target}_enabled'
 
+  def setUp(self):
+    test_discovery_agent_patcher = mock.patch('test_discovery_agent.TestDiscoveryAgent.discover_test_zip_regexes')
+    self.addCleanup(test_discovery_agent_patcher.stop)
+    self.mock_test_discovery_agent_end = test_discovery_agent_patcher.start()
+
+
   def test_build_optimization_off_builds_everything(self):
     build_targets = {'target_1', 'target_2'}
     build_planner = self.create_build_planner(