如何使用 Mockito 测试我的 DAO 方法?

Question

我正在尝试为我的DAO编写一些测试。我在这里遵循了一些教程/答案，但其中大多数都不适用于我的 DAO。

示例代码：尝试根据给定的选择器(<或>(从数据库中获取选举。

public class AdminDaoImpl extends DaoImpl implements AdminDao {
private final Logger LOGGER = Logger.getLogger(getClass().getName());
@Override
public ElectionListResponse getElections(char selector) {
ElectionListResponse electionListResponse = new ElectionListResponse();
String query = NamedQueries.GET_ELECTIONS_BEGIN + selector + NamedQueries.GET_ELECTIONS_END;
try {
con = sqlConnection.getConnection();
stmt = con.prepareStatement(query);
rs = stmt.executeQuery();
DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm");
while (rs.next()) {
Election election = new Election();
election.setElectionID(rs.getInt("id"));
election.setElectionName(rs.getString("name"));
election.setStartDate(df.format(rs.getDate("startDate")));
election.setEndDate(df.format(rs.getDate("endDate")));
electionListResponse.addElection(election);
}
return electionListResponse;
} catch (SQLException e) {
LOGGER.log(Level.SEVERE, "Cant get elections. ", e);
} finally {
closeConnection();
}
return null;
}

这是上面代码扩展的DAO：

public abstract class DaoImpl implements Dao {
private final Logger LOGGER = Logger.getLogger(getClass().getName());
@Inject
public SQLConnection sqlConnection;
public Connection con;
public PreparedStatement stmt;
public ResultSet rs;
public void closeConnection() {
try {
if (con != null) con.close();
if (stmt != null) stmt.close();
if (rs != null) con.close();
} catch (SQLException e) {
LOGGER.log(Level.SEVERE, "Can't close connection with database. ", e);
}
}
}

我尝试应用我在网上找到的一些代码，这就是我目前拥有的代码：

@RunWith(MockitoJUnitRunner.class)
public class AdminDaoImplTest {
@Mock
DataSource mockDataSource;
@Mock
Connection mockConn;
@Mock
PreparedStatement mockPreparedStmnt;
@Mock
ResultSet mockResultSet;
@BeforeClass
public static void setUpClass() throws Exception {
}
@AfterClass
public static void tearDownClass() {
}
@Before
public void setUp() throws SQLException {
when(mockDataSource.getConnection()).thenReturn(mockConn);
when(mockDataSource.getConnection(anyString(), anyString())).thenReturn(mockConn);
doNothing().when(mockConn).commit();
when(mockConn.prepareStatement(anyString(), anyInt())).thenReturn(mockPreparedStmnt);
doNothing().when(mockPreparedStmnt).setString(anyInt(), anyString());
when(mockPreparedStmnt.executeQuery()).thenReturn(mockResultSet);
when(mockResultSet.next()).thenReturn(Boolean.TRUE, Boolean.FALSE);
}
@After
public void tearDown() {
}
@Test
public void testCreateWithNoExceptions() throws SQLException {
ElectionListResponse electionListResponse = new ElectionListResponse();
AdminDaoImpl instance = new AdminDaoImpl();
instance.getElections('>' );
//verify and assert
verify(mockConn, times(1)).prepareStatement(anyString(), anyInt());
verify(mockPreparedStmnt, times(1)).execute();
verify(mockConn, times(1)).commit();
verify(mockResultSet, times(2)).next();
verify(mockResultSet, times(1)).getInt("id");
verify(mockResultSet, times(1)).getString("name");
verify(mockResultSet, times(1)).getDate("startDate");
verify(mockResultSet, times(1)).getDate("endDate");
}

}

我应该如何测试它？你能提供一些代码示例吗？提前感谢！

空指针：

java.lang.NullPointerException
at org.han.ica.oose.sneeuwklokje.database.admin.AdminDaoImpl.getElections(AdminDaoImpl.java:28)
at org.han.ica.oose.sneeuwklokje.database.admin.AdminDaoImplTest.testGetElectionsNoExceptions(AdminDaoImplTest.java:77)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.mockito.internal.runners.JUnit45AndHigherRunnerImpl.run(JUnit45AndHigherRunnerImpl.java:37)
at org.mockito.runners.MockitoJUnitRunner.run(MockitoJUnitRunner.java:62)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

Answer 1

您应该将以下字段添加到测试中：

@InjectMocks
private AdminDaoImpl

这将在您的班级中注入模拟，允许您进行测试。

你得到的 NullPointerException 可以通过这种方式修复(在测试类中(：

@Mock
private SQLConnection mockSqlConnection;

在设置方法中添加以下内容：

when(mockSqlConnection.getConnection()).thenReturn(mockConn);