[e2e] Fix overly verbose stack traces in test failures

We need to reset `reportTestException` back to the previous value after completion of `runTest`, or repeated failures will cause the exception handler for a previous test to be invoked, as they "stack". Instead of reseting it, however, do this once in the constructor because the test description is already provided by the function signature.

Author: jiahaog

packages/e2e/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.6.0+1
+
+* Fix overly verbose stack traces in test failures
+
 ## 0.6.0
 
 * **Breaking change** `E2EPlugin` exports a `Future` for `testResults`.

packages/e2e/lib/e2e.dart

@@ -39,6 +39,19 @@ class E2EWidgetsFlutterBinding extends LiveTestWidgetsFlutterBinding {
       }
       if (!_allTestsPassed.isCompleted) _allTestsPassed.complete(true);
     });
+
+    // TODO(jackson): Report the results individually instead of all at once
+    // See https://github.com/flutter/flutter/issues/38985
+    final TestExceptionReporter oldTestExceptionReporter = reportTestException;
+    reportTestException =
+        (FlutterErrorDetails details, String testDescription) {
+      _results[testDescription] = 'failed';
+      _failureMethodsDetails.add(Failure(testDescription, details.toString()));
+      if (!_allTestsPassed.isCompleted) {
+        _allTestsPassed.complete(false);
+      }
+      oldTestExceptionReporter(details, testDescription);
+    };
   }
 
   // TODO(dnfield): Remove the ignore once we bump the minimum Flutter version
@@ -120,18 +133,6 @@ class E2EWidgetsFlutterBinding extends LiveTestWidgetsFlutterBinding {
     String description = '',
     Duration timeout,
   }) async {
-    // TODO(jackson): Report the results individually instead of all at once
-    // See https://github.com/flutter/flutter/issues/38985
-    final TestExceptionReporter oldTestExceptionReporter = reportTestException;
-    reportTestException =
-        (FlutterErrorDetails details, String testDescription) {
-      _results[description] = 'failed';
-      _failureMethodsDetails.add(Failure(testDescription, details.toString()));
-      if (!_allTestsPassed.isCompleted) {
-        _allTestsPassed.complete(false);
-      }
-      oldTestExceptionReporter(details, testDescription);
-    };
     await super.runTest(
       testBody,
       invariantTester,

packages/e2e/pubspec.yaml

@@ -1,6 +1,6 @@
 name: e2e
 description: Runs tests that use the flutter_test API as integration tests.
-version: 0.6.0
+version: 0.6.0+1
 homepage: https://github.com/flutter/plugins/tree/master/packages/e2e
 
 environment: