diff --git a/packages/flutter_tools/lib/src/test/flutter_platform.dart b/packages/flutter_tools/lib/src/test/flutter_platform.dart
index 207f79930b3..93af3f414ad 100644
--- a/packages/flutter_tools/lib/src/test/flutter_platform.dart
+++ b/packages/flutter_tools/lib/src/test/flutter_platform.dart
@@ -164,7 +164,6 @@ class FlutterPlatform extends PlatformPlugin {
           harnessToTest.cancel();
           testToHarness.cancel();
 
-          assert(!controllerSinkClosed);
           switch (testResult) {
             case _TestResult.crashed:
               int exitCode = await process.exitCode;