diff --git a/test/Microsoft.TestPlatform.CrossPlatEngine.UnitTests/Client/InProcessProxyDiscoveryManagerTests.cs b/test/Microsoft.TestPlatform.CrossPlatEngine.UnitTests/Client/InProcessProxyDiscoveryManagerTests.cs
index ab6d88f3dd..5e4809f4c9 100644
--- a/test/Microsoft.TestPlatform.CrossPlatEngine.UnitTests/Client/InProcessProxyDiscoveryManagerTests.cs
+++ b/test/Microsoft.TestPlatform.CrossPlatEngine.UnitTests/Client/InProcessProxyDiscoveryManagerTests.cs
@@ -49,7 +49,7 @@ public void DiscoverTestsShouldCallInitialize()
         {
             var manualResetEvent = new ManualResetEvent(false);
             var mockTestDiscoveryEventHandler = new Mock<ITestDiscoveryEventsHandler2>();
-            this.mockDiscoveryManager.Setup(o => o.Initialize(Enumerable.Empty<string>(), mockTestDiscoveryEventHandler.Object)).Callback(
+            this.mockDiscoveryManager.Setup(o => o.Initialize(Enumerable.Empty<string>(), null)).Callback(
                 () => manualResetEvent.Set());
 
             var discoveryCriteria = new DiscoveryCriteria(new[] { "test.dll" }, 1, string.Empty);
diff --git a/test/Microsoft.TestPlatform.CrossPlatEngine.UnitTests/Client/InProcessProxyexecutionManagerTests.cs b/test/Microsoft.TestPlatform.CrossPlatEngine.UnitTests/Client/InProcessProxyexecutionManagerTests.cs
index da541f9037..0003712027 100644
--- a/test/Microsoft.TestPlatform.CrossPlatEngine.UnitTests/Client/InProcessProxyexecutionManagerTests.cs
+++ b/test/Microsoft.TestPlatform.CrossPlatEngine.UnitTests/Client/InProcessProxyexecutionManagerTests.cs
@@ -51,7 +51,7 @@ public void StartTestRunShouldCallInitialize()
             var mockTestMessageEventHandler = new Mock<ITestMessageEventHandler>();
             this.inProcessProxyExecutionManager.StartTestRun(testRunCriteria, null);
 
-            this.mockExecutionManager.Verify(o => o.Initialize(Enumerable.Empty<string>(), mockTestMessageEventHandler.Object), Times.Once, "StartTestRun should call Initialize if not already initialized");
+            this.mockExecutionManager.Verify(o => o.Initialize(Enumerable.Empty<string>(), It.IsAny<ITestMessageEventHandler>()), Times.Once, "StartTestRun should call Initialize if not already initialized");
         }
 
         [TestMethod]
diff --git a/test/Microsoft.TestPlatform.CrossPlatEngine.UnitTests/EventHandlers/TestRequestHandlerTests.cs b/test/Microsoft.TestPlatform.CrossPlatEngine.UnitTests/EventHandlers/TestRequestHandlerTests.cs
index 8b01383442..4b5d5a2d24 100644
--- a/test/Microsoft.TestPlatform.CrossPlatEngine.UnitTests/EventHandlers/TestRequestHandlerTests.cs
+++ b/test/Microsoft.TestPlatform.CrossPlatEngine.UnitTests/EventHandlers/TestRequestHandlerTests.cs
@@ -174,13 +174,12 @@ public void ProcessRequestsVersionCheckShouldLogErrorIfDiagnosticsEnableFails()
         public void ProcessRequestsDiscoveryInitializeShouldSetExtensionPaths()
         {
             var message = this.dataSerializer.SerializePayload(MessageType.DiscoveryInitialize, new[] { "testadapter.dll" });
-            var mockTestDiscoveryEventHandler = new Mock<ITestDiscoveryEventsHandler2>();
             this.ProcessRequestsAsync(this.mockTestHostManagerFactory.Object);
 
             this.SendMessageOnChannel(message);
             this.jobQueue.Flush();
 
-            this.mockDiscoveryManager.Verify(d => d.Initialize(It.Is<IEnumerable<string>>(paths => paths.Any(p => p.Equals("testadapter.dll"))), mockTestDiscoveryEventHandler.Object));
+            this.mockDiscoveryManager.Verify(d => d.Initialize(It.Is<IEnumerable<string>>(paths => paths.Any(p => p.Equals("testadapter.dll"))), It.IsAny<ITestDiscoveryEventsHandler2>()));
             this.SendSessionEnd();
         }
 
@@ -219,13 +218,12 @@ public void DiscoveryCompleteShouldSendDiscoveryCompletePayloadOnChannel()
         public void ProcessRequestsExecutionInitializeShouldSetExtensionPaths()
         {
             var message = this.dataSerializer.SerializePayload(MessageType.ExecutionInitialize, new[] { "testadapter.dll" });
-            var mockTestDiscoveryEventHandler = new Mock<ITestDiscoveryEventsHandler2>();
             this.ProcessRequestsAsync(this.mockTestHostManagerFactory.Object);
 
             this.SendMessageOnChannel(message);
             this.jobQueue.Flush();
 
-            this.mockExecutionManager.Verify(e => e.Initialize(It.Is<IEnumerable<string>>(paths => paths.Any(p => p.Equals("testadapter.dll"))), mockTestDiscoveryEventHandler.Object));
+            this.mockExecutionManager.Verify(e => e.Initialize(It.Is<IEnumerable<string>>(paths => paths.Any(p => p.Equals("testadapter.dll"))), It.IsAny<ITestMessageEventHandler>()));
             this.SendSessionEnd();
         }