How to test presenter method that create a new object inside it?

Issue

I have this method to validate Unit. I send field values and inside it method I create a new model and then return that model via interface.

public void validate(String unitNumber, Integer unitTypeId, String notes) {
if(!TextUtils.isEmpty(unitNumber)) {
      Unit unit = new Unit();
      unit.setUnitNumber(unitNumber);
      unit.setFlatTypeId(unitTypeId);
      unit.setNotes(notes);
      view.displayUnitValid(unit);
    } else {
      view.displayUnitNotValid();
    }
  }

Now I want do do unit testing of this method with the following code.

@Test public void shouldValidateSinceUnitNumberIsValid() {
    // Given
    String unitNumber = "1";

    // When
    presenter.validate(unitNumber, null, null);

    // Then
    Mockito.verify(view).displayUnitValid(new Unit());
 }

I am getting the following error message:

Argument(s) are different! Wanted:
view.displayUnitValid(
    com.rwar.domain.customers.Unit@57cf54e1
);
-> at com.rwar.presentation.work_orders.AddUnitPresenterTest.shouldValidateSinceUnitNumberIsValid(AddUnitPresenterTest.java:73)

Obvisouly there is a problem since I am creating a new Unit instance here:

Mockito.verify(view).displayUnitValid(new Unit());

And inside validate() method I create another instance of Unit.

How I can fix this?

Solution

Here is the working solution that might be useful to someone else:

 @Test public void shouldValidateSinceUnitNumberIsValid() {
    // Given
    String unitNumber = "1";

    // When
    presenter.validate(unitNumber, null, null);

    // Then use ArgumentCaptor to get unit value from newly created object inside validate() method
    ArgumentCaptor<Unit> argument = ArgumentCaptor.forClass(Unit.class);
    Mockito.verify(view).displayUnitValid(argument.capture());
    // Compare captured argument of Unit number with local unitNumber
    assertEquals(argument.getValue().getUnitNumber(), unitNumber);
  }

Answered By - Zookey