canLaunch and launch should return false if value is null

Author: mvanbeusekom

packages/url_launcher/url_launcher_platform_interface/lib/method_channel_url_launcher.dart

@@ -13,11 +13,11 @@ const MethodChannel _channel = MethodChannel('plugins.flutter.io/url_launcher');
 /// An implementation of [UrlLauncherPlatform] that uses method channels.
 class MethodChannelUrlLauncher extends UrlLauncherPlatform {
   @override
-  Future<bool?> canLaunch(String url) {
+  Future<bool> canLaunch(String url) {
     return _channel.invokeMethod<bool>(
       'canLaunch',
       <String, Object>{'url': url},
-    );
+    ).then((value) => value ?? false);
   }
 
   @override
@@ -26,7 +26,7 @@ class MethodChannelUrlLauncher extends UrlLauncherPlatform {
   }
 
   @override
-  Future<bool?> launch(
+  Future<bool> launch(
     String url, {
     required bool useSafariVC,
     required bool useWebView,
@@ -47,6 +47,6 @@ class MethodChannelUrlLauncher extends UrlLauncherPlatform {
         'universalLinksOnly': universalLinksOnly,
         'headers': headers,
       },
-    );
+    ).then((value) => value ?? false);
   }
 }

packages/url_launcher/url_launcher_platform_interface/lib/url_launcher_platform_interface.dart

@@ -38,15 +38,15 @@ abstract class UrlLauncherPlatform extends PlatformInterface {
   }
 
   /// Returns `true` if this platform is able to launch [url].
-  Future<bool?> canLaunch(String url) {
+  Future<bool> canLaunch(String url) {
     throw UnimplementedError('canLaunch() has not been implemented.');
   }
 
   /// Returns `true` if the given [url] was successfully launched.
   ///
   /// For documentation on the other arguments, see the `launch` documentation
   /// in `package:url_launcher/url_launcher.dart`.
-  Future<bool?> launch(
+  Future<bool> launch(
     String url, {
     required bool useSafariVC,
     required bool useWebView,

packages/url_launcher/url_launcher_platform_interface/test/method_channel_url_launcher_test.dart

@@ -43,6 +43,18 @@ void main() {
     final List<MethodCall> log = <MethodCall>[];
     channel.setMockMethodCallHandler((MethodCall methodCall) async {
       log.add(methodCall);
+
+      if (methodCall.method == 'canLaunch') {
+        if (methodCall.arguments['url'] == 'http://example.com/null') {
+          return null;
+        }
+      }
+
+      if (methodCall.method == 'launch') {
+        if (methodCall.arguments['url'] == 'http://example.com/null') {
+          return null;
+        }
+      }
     });
 
     final MethodChannelUrlLauncher launcher = MethodChannelUrlLauncher();
@@ -63,6 +75,12 @@ void main() {
       );
     });
 
+    test('canLaunch should return false if platform returns null', () async {
+      final canLaunch = await launcher.canLaunch('http://example.com/null');
+
+      expect(canLaunch, false);
+    });
+
     test('launch', () async {
       await launcher.launch(
         'http://example.com/',
@@ -271,6 +289,20 @@ void main() {
       );
     });
 
+    test('launch should return false if platform returns null', () async {
+      final launched = await launcher.launch(
+        'http://example.com/',
+        useSafariVC: true,
+        useWebView: false,
+        enableJavaScript: false,
+        enableDomStorage: false,
+        universalLinksOnly: false,
+        headers: const <String, String>{},
+      );
+
+      expect(launched, false);
+    });
+
     test('closeWebView default behavior', () async {
       await launcher.closeWebView();
       expect(