How to Mock ResultSet to not return null in JUnit and Mockito

Question

Im trying to test a method in a DAO which uses Calendar. This is the test I have so far:

@Test
public void testGetElectionInfo() throws SQLException {
    adminDao.getElectionInfo(1);
    verify(mockConn, times(1)).prepareStatement(anyString());
    verify(mockPreparedStmnt, times(1)).setInt(anyInt(), anyInt());
    verify(mockPreparedStmnt, times(1)).executeQuery();
    verify(mockResultSet, times(2)).next();
    verify(mockResultSet, times(1)).getString("name");
    verify(mockResultSet, times(1)).getTimestamp("startDate");
    verify(mockResultSet, times(1)).getTimestamp("endDate");
}

This is the DAO method:

public ElectionInfo getElectionInfo(int electionId) {
    ElectionInfo electionInfo = new ElectionInfo();
    try {
        con = sqlConnection.getConnection();

        stmt = con.prepareStatement(NamedQueries.GET_ELECTION_INFO);
        stmt.setInt(1, electionId);
        rs = stmt.executeQuery();

        if(rs.next()) {
            String name = rs.getString("name");
            Timestamp startDate = rs.getTimestamp("startDate");
            Timestamp endDate = rs.getTimestamp("endDate");

            Calendar startCalender = Calendar.getInstance();
            startCalender.setTime(startDate);

            Calendar endCalender = Calendar.getInstance();
            endCalender.setTime(endDate);

            electionInfo.setName(name);
            electionInfo.setStartDate(startCalender);
            electionInfo.setEndDate(endCalender);
        }

        return electionInfo;
    } catch (SQLException e) {
        LOGGER.log(Level.SEVERE, "Couldn't get the election info of the planned elections.", e);
    } finally{
        closeConnection();
    }
    return electionInfo;
}

When I run the test, it gives me a

java.lang.NullPointerException
    at java.util.Calendar.setTime

How can I resolve this issue? Could you please the post the code that solves this issue? That would help me alot!

Thanks in advance!

Can you tell us which line number did this occur? Can you add two asserts at line 14 and 15 to verify that `startDate` and `endDate` are not `null`? — jbx, Jun 08 '18 at 10:32
`verify(mockResultSet, times(1)).getTimestamp("startDate"); ` return something from this call, right now it returns a null causing it to throw a NPE — Antho Christen, Jun 08 '18 at 10:32
Possible duplicate of [java: how to mock Calendar.getInstance()?](https://stackoverflow.com/questions/9275840/java-how-to-mock-calendar-getinstance) — Rafał Sokalski, Jun 08 '18 at 10:32
@jbx it occurs in the Dao method at : startCalender.setTime(startDate); — Khiem, Jun 08 '18 at 10:36
So `startDate` is probably `null`. Can you confirm it by adding `assert startDate != null` before that line? — jbx, Jun 08 '18 at 10:37
When mocking the `ResultSet`, Mockito is returning `null` as your `startDate` and `endDate`. You need to explicitly tell it what to return. Refer to the answer by @anchreg — jbx, Jun 08 '18 at 10:40

Antho Christen · Accepted Answer · 2018-06-08T10:43:52.430

3

The line, verify(mockResultSet, times(1)).getTimestamp("startDate"); mocks the call but doesn't ask the mocking library to return a Timestamp value, and so the library returns null causing it to throw a NPE. Try changing to,

verify(mockResultSet, times(1)).getTimestamp("startDate").thenReturn(new Timestamp(0)); and likewise for the other methods too.

edited Jun 08 '18 at 10:43

answered Jun 08 '18 at 10:37

Antho Christen

1,369
1
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this did not solve the issue (andReturn didn't work), but when I saw this post, I came up with this: when(mockResultSet.getTimestamp("startDate")).thenReturn(new Timestamp(0)); when(mockResultSet.getTimestamp("endDate")).thenReturn(new Timestamp(0)); And this solved my issue! – Khiem Jun 08 '18 at 10:42
oops! corrected the method name in the answer. thanks for pointing it out! `andReturn` is in EasyMock :) – Antho Christen Jun 08 '18 at 10:44

How to Mock ResultSet to not return null in JUnit and Mockito

1 Answers1