Previous example using mockito

 package com.example.mockitoEx.MockitoEx;

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

import static org.mockito.Mockito.mock;

import static org.mockito.Mockito.when;

import org.junit.jupiter.api.Test;

class SomeBusinessTestMock {

@Test

public void findGreatestFromAllData() {

DataService dataServiceMock = mock(DataService.class);

when(dataServiceMock.retrieveAllData()).thenReturn(new int[] { 24, 15, 10 });

SomeBusinessImpl businessImpl = new SomeBusinessImpl(dataServiceMock);

int result = businessImpl.findTheGreatestFromAllData();

assertEquals(24, result);

}

}

Using mock method we can create a mock object of any interface or object.