[webview_flutter_wkwebview] Fixes bug where an NSError not an NSErrorData was returned (flutter#5973)

Author: bparrishMines

packages/webview_flutter/webview_flutter_wkwebview/example/ios/RunnerTests/FWFWebViewHostApiTests.m

@@ -351,4 +351,41 @@ - (void)testEvaluateJavaScript {
   XCTAssertEqualObjects(returnValue, @"result");
   XCTAssertNil(returnError);
 }
+
+- (void)testEvaluateJavaScriptReturnsNSErrorData {
+  FWFWebView *mockWebView = OCMClassMock([FWFWebView class]);
+
+  OCMStub([mockWebView
+      evaluateJavaScript:@"runJavaScript"
+       completionHandler:([OCMArg invokeBlockWithArgs:[NSNull null],
+                                                      [NSError errorWithDomain:@"errorDomain"
+                                                                          code:0
+                                                                      userInfo:@{
+                                                                        NSLocalizedDescriptionKey :
+                                                                            @"description"
+                                                                      }],
+                                                      nil])]);
+
+  FWFInstanceManager *instanceManager = [[FWFInstanceManager alloc] init];
+  [instanceManager addDartCreatedInstance:mockWebView withIdentifier:0];
+
+  FWFWebViewHostApiImpl *hostAPI =
+      [[FWFWebViewHostApiImpl alloc] initWithInstanceManager:instanceManager];
+
+  NSString __block *returnValue;
+  FlutterError __block *returnError;
+  [hostAPI evaluateJavaScriptForWebViewWithIdentifier:@0
+                                     javaScriptString:@"runJavaScript"
+                                           completion:^(id result, FlutterError *error) {
+                                             returnValue = result;
+                                             returnError = error;
+                                           }];
+
+  XCTAssertNil(returnValue);
+  FWFNSErrorData *errorData = returnError.details;
+  XCTAssertTrue([errorData isKindOfClass:[FWFNSErrorData class]]);
+  XCTAssertEqualObjects(errorData.code, @0);
+  XCTAssertEqualObjects(errorData.domain, @"errorDomain");
+  XCTAssertEqualObjects(errorData.localizedDescription, @"description");
+}
 @end

packages/webview_flutter/webview_flutter_wkwebview/ios/Classes/FWFWebViewHostApi.m

@@ -141,7 +141,7 @@ - (void)evaluateJavaScriptForWebViewWithIdentifier:(nonnull NSNumber *)identifie
            if (!result || [result isKindOfClass:[NSString class]] ||
                [result isKindOfClass:[NSNumber class]]) {
              returnValue = result;
-           } else {
+           } else if (![result isKindOfClass:[NSNull class]]) {
              NSString *className = NSStringFromClass([result class]);
              NSLog(@"Return type of evaluateJavaScript is not directly supported: %@. Returned "
                    @"description of value.",
@@ -151,7 +151,7 @@ - (void)evaluateJavaScriptForWebViewWithIdentifier:(nonnull NSNumber *)identifie
          } else {
            flutterError = [FlutterError errorWithCode:@"FWFEvaluateJavaScriptError"
                                               message:@"Failed evaluating JavaScript."
-                                              details:error];
+                                              details:FWFNSErrorDataFromNSError(error)];
          }
 
          completion(returnValue, flutterError);

packages/webview_flutter/webview_flutter_wkwebview/lib/src/web_kit/web_kit_api_impls.dart

@@ -908,11 +908,25 @@ class WKWebViewHostApiImpl extends WKWebViewHostApi {
   Future<Object?> evaluateJavaScriptForInstances(
     WKWebView instance,
     String javaScriptString,
-  ) {
-    return evaluateJavaScript(
-      instanceManager.getIdentifier(instance)!,
-      javaScriptString,
-    );
+  ) async {
+    try {
+      final Object? result = await evaluateJavaScript(
+        instanceManager.getIdentifier(instance)!,
+        javaScriptString,
+      );
+      return result;
+    } on PlatformException catch (exception) {
+      if (exception.details is! NSErrorData) {
+        rethrow;
+      }
+
+      throw PlatformException(
+        code: exception.code,
+        message: exception.message,
+        stacktrace: exception.stacktrace,
+        details: (exception.details as NSErrorData).toNSError(),
+      );
+    }
   }
 
   /// Calls [setNavigationDelegate] with the ids of the provided object instances.

packages/webview_flutter/webview_flutter_wkwebview/lib/src/web_kit_webview_widget.dart

@@ -573,6 +573,10 @@ class WebKitWebViewPlatformController extends WebViewPlatformController {
         return '"<null>"';
       }
       return '(null)';
+    } else if (value is bool) {
+      return value ? '1' : '0';
+    } else if (value is double && value.truncate() == value) {
+      return value.truncate().toString();
     } else if (value is List) {
       final List<String> stringValues = <String>[];
       for (final Object? listValue in value) {

packages/webview_flutter/webview_flutter_wkwebview/test/src/web_kit/web_kit_test.dart

@@ -4,6 +4,7 @@
 
 import 'dart:async';
 
+import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:mockito/annotations.dart';
 import 'package:mockito/mockito.dart';
@@ -815,6 +816,30 @@ void main() {
             .thenAnswer((_) => Future<String>.value('stopstop'));
         expect(webView.evaluateJavaScript('gogo'), completion('stopstop'));
       });
+
+      test('evaluateJavaScript returns NSError', () {
+        when(mockPlatformHostApi.evaluateJavaScript(webViewInstanceId, 'gogo'))
+            .thenThrow(
+          PlatformException(
+            code: '',
+            details: NSErrorData(
+              code: 0,
+              domain: 'domain',
+              localizedDescription: 'desc',
+            ),
+          ),
+        );
+        expect(
+          webView.evaluateJavaScript('gogo'),
+          throwsA(
+            isA<PlatformException>().having(
+              (PlatformException exception) => exception.details,
+              'details',
+              isA<NSError>(),
+            ),
+          ),
+        );
+      });
     });
 
     group('WKUIDelegate', () {

packages/webview_flutter/webview_flutter_wkwebview/test/src/web_kit_webview_widget_test.dart

@@ -634,6 +634,42 @@ void main() {
         );
       });
 
+      testWidgets('evaluateJavascript with bool return value',
+          (WidgetTester tester) async {
+        await buildWidget(tester);
+
+        when(mockWebView.evaluateJavaScript('runJavaScript')).thenAnswer(
+          (_) => Future<Object?>.value(true),
+        );
+        // The legacy implementation of webview_flutter_wkwebview would convert
+        // objects to strings before returning them to Dart. This verifies bool
+        // is represented the way it is in Objective-C.
+        // `NSNumber.description` converts bool values to a 1 or 0.
+        expect(
+          testController.evaluateJavascript('runJavaScript'),
+          completion('1'),
+        );
+      });
+
+      testWidgets('evaluateJavascript with double return value',
+          (WidgetTester tester) async {
+        await buildWidget(tester);
+
+        when(mockWebView.evaluateJavaScript('runJavaScript')).thenAnswer(
+          (_) => Future<Object?>.value(1.0),
+        );
+        // The legacy implementation of webview_flutter_wkwebview would convert
+        // objects to strings before returning them to Dart. This verifies
+        // double is represented the way it is in Objective-C. If a double
+        // doesn't contain any decimal values, it gets truncated to an int.
+        // This should be happenning because NSNumber convertes float values
+        // with no decimals to an int when using `NSNumber.description`.
+        expect(
+          testController.evaluateJavascript('runJavaScript'),
+          completion('1'),
+        );
+      });
+
       testWidgets('evaluateJavascript with list return value',
           (WidgetTester tester) async {
         await buildWidget(tester);