Initial (Android only) implementation of a WebView widget.

[amirh]

The focus of this CL is the overall widget/controller structure, and
test plumbing.
The API surface is just the bare minimum at this point (only loadUrl).

[bparrishMines]

LGTM

[bparrishMines]

nit: StandardMethodCodec() is the default value

[amirh]

done

[bparrishMines]

I think you can make this final MethodChannel _channel; by changing the constructor to:

WebViewController._(int id) : _channel = new MethodChannel(
        'plugins.flutter.io/webview_$id', const StandardMethodCodec());

[amirh]

good catch

[bparrishMines]

This way of testing works too, but you could avoid making a Mock class by doing something similar in firebase_performance.

We started testing plugins by making the MethodChannel public and using the @visibleForTesting annotation. It lets us test the actual class instead of having to always make a Fake one for testing.

[amirh]

This fake class is faking the Java implementation, the test is testing the real Dart WebView implementation.

[bparrishMines]

I was thinking of something along the lines of:

    final List<MethodCall> log = <MethodCall>[];
    WebViewController controller;
    
    Future<dynamic> methodCallHandler(MethodCall methodCall) async {
      log.add(methodCall);

      switch (methodCall.method) {
        case 'loadUrl':
          return null;
        default:
          return null;
      }
    }

    testWidgets('loadUrl', (WidgetTester tester) async {
      await tester.pumpWidget(
        WebView(
          onWebViewCreated: (WebViewController webViewController) {
            controller = webViewController;
          },
        ),
      );
      
      expect(controller, isNotNull);

      controller.channel.setMethodCallHandler(methodCallHandler);
      log.clear();

      controller.loadUrl('https://flutter.io');

      expect(log, <Matcher>[
        isMethodCall(
          'loadUrl',
          arguments: 'https://flutter.io',
        )
      ]);
    });

[amirh]

Following offline discussion we decided we're happy with the fake approach here.

[amirh]

Thanks!

[amirh]

done

[amirh]

good catch

[amirh]

This fake class is faking the Java implementation, the test is testing the real Dart WebView implementation.