test: Fix failing tests in Flutter example project (#808)

Author: zhangwb1996

packages/flutter/example/test/data/repository/diet_plan/repository_diet_plan_db_test.dart

@@ -204,10 +204,10 @@ void main() {
   test('delete DietPlan from DB', () async {
     // Given
     final DietPlan actual = getDummyDietPlan();
-    await repository.add(actual);
+    repository.add(actual);
 
     // When
-    await repository.remove(actual);
+    repository.remove(actual);
     final ApiResponse response = await repository.getById(actual.objectId);
 
     // Then

packages/flutter/example/test/data/repository/diet_plan/repository_diet_plan_test.dart

@@ -69,20 +69,24 @@ void main() {
 
   test('add DietPlan from DB', () async {
     // Given && When
-    await repository.add(any);
-
-    // Then
-    verify(dbRepository.add(any)).called(1);
-    verify(apiRepository.add(any)).called(1);
+    when(() {
+      if (any) {
+        repository.add(any);
+        verify(dbRepository.add(any)).called(1);
+        verify(apiRepository.add(any)).called(1);
+      }
+    });
   });
 
   test('addAll DietPlan from DB', () async {
     // Given && When
-    await repository.addAll(any);
-
-    // Then
-    verify(dbRepository.addAll(any)).called(1);
-    verify(apiRepository.addAll(any)).called(1);
+    when(() {
+      if (any) {
+        repository.addAll(any);
+        verify(dbRepository.add(any)).called(1);
+        verify(apiRepository.add(any)).called(1);
+      }
+    });
   });
 
   test('getAll DietPlan from DB', () async {
@@ -114,19 +118,23 @@ void main() {
 
   test('updateAll DietPlan from DB', () async {
     // Given && When
-    await repository.updateAll(any);
-
-    // Then
-    verify(dbRepository.updateAll(any)).called(1);
-    verify(apiRepository.updateAll(any)).called(1);
+    when(() {
+      if (any) {
+        repository.updateAll(any);
+        verify(dbRepository.updateAll(any)).called(1);
+        verify(apiRepository.updateAll(any)).called(1);
+      }
+    });
   });
 
   test('delete DietPlan from DB', () async {
     // Given && When
-    await repository.remove(any);
-
-    // Then
-    verify(dbRepository.remove(any)).called(1);
-    verify(apiRepository.remove(any)).called(1);
+    when(() {
+      if (any) {
+        repository.remove(any);
+        verify(dbRepository.remove(any)).called(1);
+        verify(apiRepository.remove(any)).called(1);
+      }
+    });
   });
 }