Test DriverManager.getConnection with mockito

Question

I wrote DAO class

public List<ClassRoom> getAllClassRooms() {
    List<ClassRoom> classRoomsList = new ArrayList<>();
    String sqlStatement = "SELECT * FROM university.classrooms;";
    try {
        Class.forName("org.postgresql.Driver");
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }
    Connection connection = null;
    PreparedStatement statement = null;
    ResultSet resultSet = null;
    try {
        connection = DriverManager.getConnection("jdbc:postgresql://127.0.0.1:5432/Exam6", "postgres", "Navlanart1");
        try {
            statement = connection.prepareStatement(sqlStatement);
            try {
                resultSet = statement.executeQuery();
                while (resultSet.next()) {
                    ClassRoom classRoom = new ClassRoom(resultSet.getString("name"));
                    classRoomsList.add(classRoom);
                }
            } catch (SQLException e) {
            } finally {
                try {
                    resultSet.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                statement.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    } catch (SQLException e) {
        e.printStackTrace();
    } finally {
        try {
            connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    return classRoomsList;
}

Now i want to test it by class like that

import static org.mockito.Matchers.anyString;
import static org.mockito.Mockito.times;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.when;
import static org.powermock.api.easymock.PowerMock.mockStatic;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import org.junit.AfterClass;
import org.junit.Before;
import org.junit.BeforeClass;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mock;
import org.mockito.runners.MockitoJUnitRunner;
import org.powermock.core.classloader.annotations.PrepareForTest;

import com.kolosok.university.dao.ClassRoomDao;

@RunWith(MockitoJUnitRunner.class)
@PrepareForTest(DriverManager.class)
public class TestClassRoomDao {

@Mock
Connection mockConnection;

@Mock
PreparedStatement mockPreparedStatement;

@Mock
ResultSet mockResultSet;

@Test
public void testGetAllClassRooms() throws SQLException {

    mockStatic(DriverManager.class);

    when(DriverManager.getConnection(anyString(), anyString(), anyString())).thenReturn(mockConnection);
    when(mockConnection.prepareStatement(anyString())).thenReturn(mockPreparedStatement);
    when(mockPreparedStatement.executeQuery()).thenReturn(mockResultSet);
    when(mockResultSet.next()).thenReturn(Boolean.FALSE);

    ClassRoomDao classRoomDao = new ClassRoomDao();
    classRoomDao.getAllClassRooms();

    verify(mockConnection, times(1)).prepareStatement(anyString());
    verify(mockPreparedStatement, times(1)).executeQuery();
    verify(mockResultSet, times(1)).next();
}

}

But it doesnt work.

java.sql.SQLException: No suitable driver found for 
    at java.sql.DriverManager.getConnection(Unknown Source)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at     com.kolosok.university.TestClassRoomDao.testGetAllClassRooms(TestClassRoomDao.java:58)

I read alot of stackOverFlow answers on similar quastions. But still cant solve my issue

I'm using

postgresql-42.0.0.jre7.jar

mockito-all-1.10.19.jar

powermock-api-easymock-1.6.6.jar

powermock-core-1.6.6.jar

cglib-nodep-3.1.jar

javassist-3.12.1.GA.jar

objenesis-2.5.jar

powermock-api-mockito-1.6.6.jar

powermock-api-support-1.6.6.jar

easymock-3.4.jar

Answer 1

I think the problem may be that you are not running this with the PowerMockRunner, so the PowerMock extensions to are using ( like mockStatic ) aren't obeyed

Try changing @RunWith(MockitoJUnitRunner.class) to @RunWith(PowerMockRunner.class)

EDIT

You may also need to initialize the mocks. Easiest way is to use an @Before method, something like

@Before public void setup(){ initMocks(this); }

Answer 2

Class Cut{
    public void abc(){
        Connection conn = DriverManager.getConnection("url","username","password");
    }
}


@PrepareForTest({Cut.class})
Class Cut_test{

    cut classUnderTest;

    public void abc_test(){

    PowerMockito.mockStatic(DriverManager.class);
    when(DriverManager.getConnection(anyString(),anyString(),anyString())).thenReturn(mockConnection);

    //test the stub
    Connection conn = DriverManager.getConnection("abc","abc","pass");

    //call actual method 
    classunderTest.abc();

    //Assert
    assertTrue("passed",true);
}

for those getting nullpointerException,

1. check if the stub is working by adding the lines under //test the stub.
2. comment out your DriverManager.getConnection in actual code .
3. replace with //test the stub i posted above .
4. then run the test method in debug mode and see if it reaches the actual method.
5. if it didn't reach then add the actual method's class in @PrepareForTest({KafkaRecordHandler.class})