java – How to mock Springs JdbcTemplate.queryForList using Mockito?

java – How to mock Springs JdbcTemplate.queryForList using Mockito?

This should work:

import org.hamcrest.CoreMatchers;
import org.junit.Assert;
import org.junit.Test;
import org.mockito.ArgumentMatchers;
import org.mockito.Mockito;
import org.springframework.jdbc.core.JdbcTemplate;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

public class DemoTest {

    @Test
    public void mockJdbcTemplate() {
        JdbcTemplate mockTemplate = Mockito.mock(JdbcTemplate.class);

        List<Map<String, Object>> mockResult = new ArrayList<>();

        Mockito.when(mockTemplate.queryForList(Mockito.anyString(), ArgumentMatchers.<Object>any())).thenReturn(mockResult);
        // Alternatively:
        // when(mockTemplate.queryForList(anyString(), Mockito.<Object>any())).thenReturn(mockResult);

        String query = some query;
        Object[] params = new Object[]{1};

        List<Map<String, Object>> returnedResult = mockTemplate.queryForList(query, params);

        Assert.assertThat(returnedResult, CoreMatchers.sameInstance(mockResult));
    }

}

The trick is to use ArgumentMatchers.<Object>any() as there are multiple queryForList method implementations and the one we want to mock receives a varargs parameter.

Following code i used with spring boot, mockito

/** class on which uni test is driven **/
public class Decompile {


    @Autowired
    private JdbcTemplate jdbcTemplate;

    public List<Map<String, Object>> getRunner()
    {
        try{
            return jdbcTemplate.queryForList(select * from users);
        } 
        catch (Exception e) {
            System.err.println(e);
        }
        return null;
    }

}

Unit test case starts

/** Unit test case for above class **/
import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.Mockito;
import org.mockito.MockitoAnnotations;
import org.mockito.junit.MockitoJUnitRunner;
import org.springframework.jdbc.core.JdbcTemplate;

@RunWith(MockitoJUnitRunner.class)
public class DecompileTest {

    @Mock/* works fine with autowired dependency too */
    JdbcTemplate jdbcTemplate;

    @InjectMocks/* for the claa that we are mocking */
    Decompile testclass;

    @Before
    public void setUp() throws Exception {
        MockitoAnnotations.initMocks(this);
    }

    @Test
    public void testgetRunner() {
        List<Map<String, Object>> expectedresultList  = new ArrayList<>();
        Mockito.lenient().when(jdbcTemplate.queryForList(select * from users.. )).thenReturn(expectedresultList);
        List<Map<String, Object>> response = testclass.getRunner();
    }

}

mvn package used as following (compatible with spring version > 2)

<dependency> 
    <groupId>org.springframework.boot</groupId> 
    <artifactId>spring-boot-test</artifactId> 
    <scope>test</scope> 
</dependency> 

<dependency>
    <groupId>org.springframework.boot</groupId> 
    <artifactId>spring-boot-starter-test</artifactId> 
    <scope>test</scope> 
</dependency> 

java – How to mock Springs JdbcTemplate.queryForList using Mockito?