[英]How to test DAO methods using Mockito?
我已经开始发现 Mockito 库,并且有一个问题我没有找到正确的答案。
例如,如果我的 UserDAO 类中有这样的方法,可以将用户保存在数据库中:
public class UserDAO{
...
public void create(User user) {
Connection connection = null;
PreparedStatement pstmt = null;
ResultSet generatedKeys = null;
try {
connection = getConnection();
pstmt = connection.prepareStatement(INSERT_USER,
PreparedStatement.RETURN_GENERATED_KEYS);
int counter = 1;
pstmt.setString(counter++, user.getFirstName());
pstmt.setString(counter++, user.getLastName());
pstmt.setString(counter++, user.getEmail());
pstmt.setString(counter++, user.getPassword());
pstmt.setString(counter++, user.getRole());
pstmt.setString(counter, user.getLang());
pstmt.execute();
connection.commit();
generatedKeys = pstmt.getGeneratedKeys();
if (generatedKeys.next()) {
user.setId(generatedKeys.getInt(Fields.GENERATED_KEY));
}
} catch (SQLException e) {
rollback(connection);
LOG.error("Can not create a user", e);
} finally {
close(connection);
close(pstmt);
close(generatedKeys);
}
}
....
}
我应该如何测试它?
如果我想测试一个 DAO 类,那么我需要创建一个DataSource
mock、 Connection
mock、 ResultSet
mock 等吗? 所以不测试数据库本身?
但是如果我还想测试 dao 和 database 的行为呢?
您能否提供一些代码示例、可能有用的链接并展示最佳方法?
这是使用 Mockito 测试 UserDAO 的良好开端。 此代码使用了大量的 Mockito 功能,因此您可以了解如何使用它们。 如果您有任何问题,请告诉我。
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.sql.DataSource;
import org.junit.After;
import org.junit.AfterClass;
import org.junit.Before;
import org.junit.BeforeClass;
import org.junit.Test;
import static org.junit.Assert.*;
import org.junit.runner.RunWith;
import static org.mockito.Matchers.anyInt;
import static org.mockito.Matchers.anyString;
import org.mockito.Mock;
import static org.mockito.Mockito.doNothing;
import static org.mockito.Mockito.times;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.when;
import org.mockito.runners.MockitoJUnitRunner;
@RunWith(MockitoJUnitRunner.class)
public class TestUserDAO {
@Mock
DataSource mockDataSource;
@Mock
Connection mockConn;
@Mock
PreparedStatement mockPreparedStmnt;
@Mock
ResultSet mockResultSet;
int userId = 100;
public TestUserDAO() {
}
@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.execute()).thenReturn(Boolean.TRUE);
when(mockPreparedStmnt.getGeneratedKeys()).thenReturn(mockResultSet);
when(mockResultSet.next()).thenReturn(Boolean.TRUE, Boolean.FALSE);
when(mockResultSet.getInt(Fields.GENERATED_KEYS)).thenReturn(userId);
}
@After
public void tearDown() {
}
@Test
public void testCreateWithNoExceptions() throws SQLException {
UserDAO instance = new UserDAO(mockDataSource);
instance.create(new User());
//verify and assert
verify(mockConn, times(1)).prepareStatement(anyString(), anyInt());
verify(mockPreparedStmnt, times(6)).setString(anyInt(), anyString());
verify(mockPreparedStmnt, times(1)).execute();
verify(mockConn, times(1)).commit();
verify(mockResultSet, times(2)).next();
verify(mockResultSet, times(1)).getInt(Fields.GENERATED_KEYS);
}
@Test(expected = SQLException.class)
public void testCreateWithPreparedStmntException() throws SQLException {
//mock
when(mockConn.prepareStatement(anyString(), anyInt())).thenThrow(new SQLException());
try {
UserDAO instance = new UserDAO(mockDataSource);
instance.create(new User());
} catch (SQLException se) {
//verify and assert
verify(mockConn, times(1)).prepareStatement(anyString(), anyInt());
verify(mockPreparedStmnt, times(0)).setString(anyInt(), anyString());
verify(mockPreparedStmnt, times(0)).execute();
verify(mockConn, times(0)).commit();
verify(mockResultSet, times(0)).next();
verify(mockResultSet, times(0)).getInt(Fields.GENERATED_KEYS);
throw se;
}
}
}
但是如果我还想测试 dao 和 database 的行为呢?
如果您确实想测试数据库(正如您应该做的那样!),没有办法解决它 - 您需要一个实际的数据库。 Mockito 虽然是一个很棒的库,但可能是这项工作的错误工具。
以下是您应该如何测试它:
public class UserDAOTest extends IntegrationTests
{
// Or do it in a @Before method, if needed.
UserDAO dao = new UserDAO();
@Test
public void createValidUser() {
User validUser = new User(
"John", "Smith", "johns@gmail.com", "Abc123!@",
"admin", "en"); // or use setters as needed
dao.create(validUser);
assertEntityCreatedInDB(validUser);
}
@Test
public void attemptToCreateInvalidUser() {
User invalidUser = new User("", null, null, "", null, "XY");
dao.create(invalidUser);
// This really shouldn't be done this way, as DAOs are not supposed
// to manage transactions; instead, a suitable, descriptive
// exception should be thrown by the DAO and checked in the test.
assertTransactionWasRolledBack();
}
}
关于上述内容的几点说明:
1) 测试看起来简短、简单、易于理解,应该是这样; 如果它们看起来像另一个答案中的那些又大又丑,那么你做的事情根本上是错误的。
2) 测试代码可以而且应该有自己的基础设施助手,例如IntegrationTests
基类,它将隐藏任何对实际测试的讨厌的 JDBC/ORM 访问。 我在几个项目中实现了这样的助手,所以我知道这是可以做到的,但这将是其他问题的东西。
像DBUnit和 JUnit 这样的工具可以帮助您使用数据库测试您的 DAO。 DBUnit 帮助您在 UnitTest 之前将测试数据插入数据库,并在测试之后将数据库中的数据与您的期望进行比较。
这是我的测验应用程序中的一个示例
@Test
fun quizDao() {
val database = mockk<AppDatabase>()
val dao = mockk<QuizDao>()
val application = mockk<Application>()
val appModule = mockk<AppModule>()
//quiz
val quiz1 = Quiz("Joe","Best Quize","people Around the World","General",23)
//Questions
val questions1 : Questions = Questions(1,"What's your group", "G1","G2","G3","G4","G1")
every { dao.getQuizQuestions(23) } returns listOf(questions1)
assertEquals(listOf(questions1),dao.getQuizQuestions(23))
}
}
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