How to mock AmazonSQS in unit test to not make a call to SQS?

Question

I have the following method in my Java class:

public class AwsHelper {

  private AmazonSQS sqs;

  private void sendMessageToQueue(String message){

        sqs = AmazonSQSClientBuilder.defaultClient();

        SendMessageRequest sendMessageRequest = new SendMessageRequest();
        sendMessageRequest.setQueueUrl("");
        sendMessageRequest.setMessageBody(message);
        sendMessageRequest.setMessageGroupId("");

        sqs.sendMessage(sendMessageRequest);
}

I want to be able to mock the behavior of sqs.sendMessage(sendMessageRequest);so that my unit test does not send a message to a queue.

I have tried to do so as follows in my test class, but sqs actually sends a message to the queue when my test is executed. Assume this is due to being assigned by AmazonSQSClientBuilder.defaultClient().

How can I solve this?

public class AwsSQSReferralsUtilTest {
    
        @Spy
        @InjectMocks
        private AwsHelper awsHelper;
    
        @Mock
        AmazonSQS sqs;
    
        @BeforeClass
        public void setUp() {
            MockitoAnnotations.initMocks(this);
        }
    
        @AfterMethod
        public void afterEachMethod() {
            Mockito.reset(awsHelper);
        }
    
        @Test
        public void shouldSendMessage() {
    
            Mockito.when((sqs.sendMessage(any(SendMessageRequest.class)))).thenReturn(new SendMessageResult());
    
            awsHelper.sendMessageToQueue("");
        }
}

Answer 1

I recommend to use approach from article: https://github.com/mockito/mockito/wiki/Mocking-Object-Creation

You need to change little bit a class, applying approach for mocking from article in following way:

AwsHelper

public class AwsHelper {

    private AmazonSQS sqs;

    public void sendMessageToQueue(String message) {
        sqs = defaultClient();

        SendMessageRequest sendMessageRequest = new SendMessageRequest();
        sendMessageRequest.setQueueUrl("");
        sendMessageRequest.setMessageBody(message);
        sendMessageRequest.setMessageGroupId("");

        sqs.sendMessage(sendMessageRequest);
    }

    protected AmazonSQS defaultClient() {
        return AmazonSQSClientBuilder.defaultClient();
    }
}

AwsSQSReferralsUtilTest

public class AwsSQSReferralsUtilTest {

    @Spy
    private AwsHelper awsHelper;

    @Mock
    private AmazonSQS sqs;

    @BeforeClass
    public void setUp() {
        MockitoAnnotations.initMocks(this);
    }
    
    @AfterMethod
    public void afterEachMethod() {
        Mockito.reset(awsHelper);
    }

    @Test
    public void shouldSendMessage() {
        //mocking object creation
        doReturn(sqs).when(awsHelper).defaultClient();

        when(sqs.sendMessage(any(SendMessageRequest.class))).thenReturn(new SendMessageRequest());
        awsHelper.sendMessageToQueue("");
    }

}