Fix Tests

• Fixes an issue with the tests. Apparently Flutter no longer bundles its test framework automatically and it must now be included as an explicit dependency.

pubspec.yaml

@@ -14,6 +14,7 @@ dependencies:
     sdk: flutter
 
 dev_dependencies:
+  test: ^1.5.1
   flutter_test:
     sdk: flutter
 

test/mock_channel.dart

@@ -64,6 +64,12 @@ class OneSignalMockChannelController {
       case "OneSignal#deleteTags":
         this.state.deleteTags = call.arguments;
         return {"success": true};
+      case "OneSignal#setExternalUserId":
+        this.state.externalId = (call.arguments as Map<dynamic, dynamic>)['externalUserId'] as String;
+        return {"success" : true};
+      case "OneSignal#removeExternalUserId":
+        this.state.externalId = null;
+        return {"success" : true};
     }
   }
 }
@@ -90,6 +96,7 @@ class OneSignalState {
   bool locationShared;
   OSNotificationDisplayType inFocusDisplayType;
   bool subscriptionState;
+  String externalId;
 
   // tags
   Map<dynamic, dynamic> tags;

test/onesignal_test.dart

@@ -111,4 +111,16 @@ void main() {
       expect(channelController.state.deleteTags, ['test1']);
     }));
   });
+
+  test('setting external user ID', () {
+    onesignal.setExternalUserId('test_ext_id').then(expectAsync1((v) {
+      expect(channelController.state.externalId, 'test_ext_id');
+    }));
+  });
+
+  test('removing external user ID', () {
+    onesignal.removeExternalUserId().then(expectAsync1((v) {
+      expect(channelController.state.externalId, null);
+    }));
+  });
 }