Unit test – InvalidUseOfMatchersException

Unit test – InvalidUseOfMatchersException

Problem Description:

I am trying to write test for the function, rollDays. However, I am getting InvalidUseOfMatchersException.
rollDays is inside CalculateDateService:

public class CalculateDateService {
 
    LocalDate rollDays(int days, LocalDate date, String mar) {
        int dir = days > 0 ? 1 : -1;
        for(int numOfDays = Math.abs(days); closed(date, mar) || numOfDays-- > 0; date = date.plusDays((long) dir)) {

        }
        return date;
    }

    Boolean closed(LocalDate date, String mar) {
        return this.nonSettle(date);
    }

    Boolean nonSettle(LocalDate date) {
        int year = LocalDate.now().getYear();
        LocalDate dayBeforeChristmas = LocalDate.of(year, 12, 24);
        LocalDate dayBeforenewYear = LocalDate.of(year, 12, 31);
        return (date.isEqual(dayBeforeChristmas) || date.isEqual(dayBeforenewYear));
    }
}

The test:

@InjectMocks
private CalculateDateService tested;

@Test
public void testRollDays() {

Mockito.when(tested.nonSettle(Mockito.any(LocalDate.class))).thenReturn(Boolean.FALSE);
Mockito.when(tested.nonSettle (LocalDate.of(2021,12,24))).thenReturn(Boolean.TRUE);
LocalDate result = tested.rollDays(2, LocalDate.of(2021, 12, 22));
LocalDate correctRolledDate = LocalDate.of(2021, 12, 25);
assertEquals(result, correctRolledDate);
}       

The error I got is:

org.mockito.exceptions.misusing.InvalidUseOfMatchersException:
Invalid use of argument matchers!

and something along the line of “expected matcher 0, but got 1”

I tried updating the test part to be

Mockito.when(tested.nonSettle(LocalDate.of(2022,12,22))).thenReturn(Boolean.FALSE);
Mockito.when(tested.nonSettle(LocalDate.of(2022,12,23))).thenReturn(Boolean.FALSE);
Mockito.when(tested.nonSettle(LocalDate.of(2022,12,25))).thenReturn(Boolean.FALSE);
Mockito.when(tested.nonSettle(LocalDate.of(2022,12,24))).thenReturn(Boolean.TRUE);

to avoid using matcher
but I got NullPointerException instead which happened for the line within nonSettle LocalDate dayBeforeChristmas = LocalDate.of(year, 12, 24);
Any help will be greatly appreciated, thank you in advance.

Solution – 1

Your example still has errors, but i managed to correct it. Your issue is with
Mockito.when(something.isCalled()).thenReturn(something); something needs to be a mock, in your case, it’s not, tested is an instance of CalculateDateService. You can read more about @Mock and @InjectMocks here.

So, you just have to comment/remove your Mockito.when() statements, and everything will work. For example, this works:

package com.example;

import static org.junit.jupiter.api.Assertions.assertEquals;

import java.time.LocalDate;

import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;
import org.mockito.InjectMocks;
import org.mockito.junit.jupiter.MockitoExtension;

@ExtendWith(MockitoExtension.class)
class CalculateDateServiceTest {
    
    @InjectMocks
    private CalculateDateService tested;
    
    @Test
    void testRollDays() {
                
        LocalDate result = tested.rollDays(2, LocalDate.of(2021, 12, 22));
        LocalDate correctRolledDate = LocalDate.of(2021, 12, 24);
        assertEquals(result, correctRolledDate);
    }       
}

Unit Test:

package com.example;

import java.time.LocalDate;

public class CalculateDateService {
    LocalDate rollDays(int days, LocalDate date) {
        int dir = days > 0 ? 1 : -1;
        for(int numOfDays = Math.abs(days); closed(date) || numOfDays-- > 0; date = date.plusDays((long) dir)) {

        }
        return date;
    }

    Boolean closed(LocalDate date) {
        return this.nonSettle(date);
    }

    Boolean nonSettle(LocalDate date) {
        int year = LocalDate.now().getYear();
        LocalDate dayBeforeChristmas = LocalDate.of(year, 12, 24);
        LocalDate dayBeforenewYear = LocalDate.of(year, 12, 31);
        return (date.isEqual(dayBeforeChristmas) || date.isEqual(dayBeforenewYear));
    }
}

Also, the @InjectMocks is not required, as there are no mocks to inject. You can just use CalculateDateService tested = new CalculateDateService(); in your test method.

By the way, your for loop(although it works) and your method name are confusing. You might want to review/rewrite those.