I don't want to use powermock anymore. Because junit5 started mocking static classes. So i am trying to get rid of powermock methods.
As you know, you can create an instance of a class with whenNew keyword. So i decided to use " mockConstruction " . But mockConstruction does not return the mocked object. It doesn't go inside the try block.
This is my BeforeEach method:
@BeforeEach void setUp() { partUnlinkService = spy(new PartVideoUnlinkService(part1, part2, part3)); }This is my test method:
@Test void shouldThrowException() throws Exception { //given UrlLinkDto urlLinkDto = UrlPartLinkDto.builder().callId("333").videoId("5555544").build(); ArgumentCaptor<UrlPartLinkDto> argumentCaptor = ArgumentCaptor.forClass(UrlPartLinkDto.class); //when try (MockedConstruction<ObjectMapper> ignoredVariable = mockConstruction(ObjectMapper.class, (objectMapper, context) -> { //then partUnlinkService.unlink(urlLinkDto, false); verify(partLogCheckService, times(1)).checkForExistingVideo( urlLinkDto.getVideoId()); verify(objectMapper, times(1)).writeValueAsString(argumentCaptor.capture()); Throwable throwable = catchThrowable(() -> objectMapper.writeValueAsString(argumentCaptor.capture())); assertThat(throwable).isInstanceOf(JsonProcessingException.class); })) { } }Any help would be appreciated.
2 Answers
You can access mocks that were created during the instantiation of your objects via MockedConstruction.constructed() method. It represents a collection of mocks that are created after each constructor's execution. If your object will be instantiated 3 times MockedConstruction<T>.constructed() will return 3 different mock objects for each instantiation.
According to documentation MockedConstruction<T>
Represents a mock of any object construction of the represented type. Within the scope of the mocked construction, the invocation of any interceptor will generate a mock which will be prepared as specified when generating this scope. The mock can also be received via this instance.
Simple implementation with comments below shows how to get mocks from MockedConstruction and verify them:
public class A { private final String test; public A(String test) { this.test = test; } public String check() { return "checked " + this.test; }
}
public class TestService { public String purchaseProduct(String param) { A a = new A(param); return a.check(); }
}
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.mockito.MockedConstruction;
import org.mockito.Mockito;
import static org.mockito.Mockito.*;
public class ConstructorMockTest { private MockedConstruction<A> mockAController; @BeforeEach public void beginTest() { //create mock controller for all constructors of the given class mockAController = Mockito.mockConstruction(A.class, (mock, context) -> { //implement initializer for mock. Set return value for object A mock methods when(mock.check()).thenReturn(" Constructor Mock A "); }); } @Test public void test() { //each instantiation of class A will return new mock, which initialized by initializer from beginTest method //new mock will be stored to mockAController.constructed() collection of mocks A aObject = new A("test"); //ensure that method check() returns mocked value Assertions.assertEquals(aObject.check(), " Constructor Mock A "); //get just created mock for class A from controller. It will be first element of mockAController.constructed() collection A aMock = mockAController.constructed().get(0); //ensure that we get correct mock from mock controller, that it is equal from new created object Assertions.assertEquals(aMock, aObject); //verify that check method was executed on Mock verify(aMock, times(1)).check(); //create new A object, new mock created and stored to mockAController.constructed() A aObject2 = new A("test"); //ensure that method check() returns mocked value Assertions.assertEquals(aObject2.check(), " Constructor Mock A "); //get just created mock for class A from controller, it will be second object from constructed collection A aMock2 = mockAController.constructed().get(1); //ensure that we get correct mock from mock controller, that it is equal from just created A object Assertions.assertEquals(aObject2, aMock2); //verify that check method was executed on Mock verify(aMock2, times(1)).check(); //Example of testing service which creates A object TestService service = new TestService(); String serviceResult = service.purchaseProduct("test"); //ensure that service returned value from A mock Assertions.assertEquals(serviceResult, " Constructor Mock A "); //get just created mock for class A from controller, it will be third object from constructed collection A aMock3 = mockAController.constructed().get(2); //verify that check method was executed on Mock verify(aMock3, times(1)).check(); } @AfterEach public void endTest() { mockAController.close(); }
}Let's rewrite your test. I do not have the full code, but I will try to create an example with comments:
@Test void shouldThrowException() throws Exception { //given UrlLinkDto urlLinkDto = UrlPartLinkDto.builder().callId("333").videoId("5555544").build(); ArgumentCaptor<UrlPartLinkDto> argumentCaptor = ArgumentCaptor.forClass(UrlPartLinkDto.class); try (MockedConstruction<ObjectMapper> objectMapperMockedConstruction = mockConstruction(ObjectMapper.class, (objectMapper, context) -> { //initialize ObjectMapper mock to throw exception when argumentCaptor will come to writeValueAsString method doThrow(JsonProcessingException.class).when(objectMapper).writeValueAsString(argumentCaptor.capture()); })) { //execute service for testing and catch exception Throwable throwable = catchThrowable(() -> partUnlinkService.unlink(urlLinkDto, false)); //verify that inner service was executed verify(partLogCheckService, times(1)).checkForExistingVideo(urlLinkDto.getVideoId()); //verify that ObjectMapper was instantiated Assertions.assertEquals(1, objectMapperMockedConstruction.constructed().size()); //get mock of ObjectMapper which was instantiated during service execution ObjectMapper objectMapper = objectMapperMockedConstruction.constructed().get(0); //verify that writeValueAsString was executed verify(objectMapper, times(1)).writeValueAsString(argumentCaptor.capture()); //check that exception is correct assertThat(throwable).isInstanceOf(JsonProcessingException.class); } }I think I have the same question as you, hope someone can solve our problem.
In my case, I also want to got a return object like PowerMock.whenNew().withArguments().thenReturn(someThing), I try a lot of times but it failed. I think mockConstruction just only can mock their behavior, can't verify their result like powerMock, and I couldn't find any articles or answers. below is my post link :
