Platform Developer Certification Maintenance (Winter ’25)-> Get Hands-On with an Iterable Variable in For Loops

I tried all possible solution still facing below error and need to complete it by 5th december 2025. Please help me on this.    Error :   Challenge not yet complete.  We can't find the last successful test run that invokes the testIterableForLoop method. Run the test again and check the test run results for more details.

================================================= 

My Code:    MyIterable.apxc -  public class MyIterable implements Iterable<String> {     private List<String> strings;       public MyIterable(List<String> strings){      this.strings = strings;     }            public Iterator<String> iterator(){      return strings.iterator();      }  }    MyIterableTest .apxc  @IsTest  public class MyIterableTest {        @IsTest      public static void testIterableForLoop(){          List<String> strings = new List<String> {'Hello', 'World'};           MyIterable myIterable = new MyIterable(strings);           // Test.startTest();           for(String str: myIterable)           {                        System.debug(str);                 }          //Test.stopTest();      }  }