Added tests

Author: Jan-Derk

test/method_channel_mock.dart

@@ -0,0 +1,32 @@
+import 'package:flutter/services.dart';
+
+class MethodChannelMock {
+  final MethodChannel methodChannel;
+  final String method;
+  final dynamic result;
+  final Duration delay;
+
+  MethodChannelMock({
+    required String channelName,
+    required this.method,
+    this.result,
+    this.delay = Duration.zero,
+  }) : methodChannel = MethodChannel(channelName) {
+    methodChannel.setMockMethodCallHandler(_handler);
+  }
+
+  Future _handler(MethodCall methodCall) async {
+    if (methodCall.method != method) {
+      throw MissingPluginException('No implementation found for method '
+          '$method on channel ${methodChannel.name}');
+    }
+
+    return Future.delayed(delay, () {
+      if (result is Exception) {
+        throw result;
+      }
+
+      return Future.value(result);
+    });
+  }
+}