How to return different value in Mockito based on parameter attribute?

Question

The class that I test receive a client wrapper:

The tested class (snippest)

private ClientWrapper cw public Tested(ClientWrapper cw) {     this.cw = cw; }  public String get(Request request) {     return cw.getClient().get(request); } 

The test initialization:

ClientWrapper cw = Mockito.mock(ClientWrapper.class); Client client = Mockito.mock(Client.class); Mockito.when(cw.getClient()).thenReturn(client); //Here is where I want to alternate the return value: Mockito.when(client.get(Mockito.any(Request.class))).thenReturn("100"); 

In the exmaple I always return "100", but the Request have an attribute id and I would like to return different values to client.get(Request) based on the request.getId() value.

How can I do it?

Answer 1

You can use Mockito's answers, so instead of:

Mockito.when(client.get(Mockito.any(Request.class))).thenReturn("100"); 

write:

Mockito.when(client.get(Mockito.any(Request.class)))  .thenAnswer(new Answer() {    Object answer(InvocationOnMock invocation) {      Object[] args = invocation.getArguments();      Object mock = invocation.getMock();      return "called with arguments: " + args;    } }); 

Answer 2

In order to do it right and with minimal code you have to use the ArgumentMatcher, lambda expression & don't forget to do a null check on the filters members in the ArgumentMatcher lambda (especially if you have more than one mock with the same ArgumentMatcher).

Customized argument matcher:

private ArgumentMatcher<Request> matchRequestId(final String target) {     return request -> request != null &&             target.equals(request.getId()); } 

Usage:

 given(client.get(argThat(matchRequestId("1")))).willReturn("100");  given(client.get(argThat(matchRequestId("2")))).willReturn("200");