java - Powermock 无法模拟 MysqlConnect

Question

这是我的 Mysql 类:

public class MysqlConnection {

    public Connection MysqlConnect() {
        String url = "jdbc:mysql://localhost:3306/";
        String dbName = "dashboard";
        String driver = "com.mysql.jdbc.Driver";
        String userName = "root";
        String passwd = "";
        Connection conn = null;
        try {
            Class.forName(driver);
            conn = DriverManager.getConnection(url+dbName,userName,passwd);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return conn;
    }
}

而我的 PowerMockito 测试类是这样的:

@RunWith(PowerMockRunner.class)
@PowerMockIgnore("javax.management.*")
@PrepareForTest(Class.class)
public class MysqlConnectionTest {

    @Test(expected = ClassNotFoundException.class)
    public void MysqlConnectiontest() {
        PowerMockito.mockStatic(Class.class);
        try {
            when(Class.forName(Mockito.anyString())).thenThrow(new ClassNotFoundException("error message"));
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        obj.MysqlConnect();
    }
}

错误的Stacktrace是:

java.lang.AssertionError: Expected exception: java.lang.ClassNotFoundException
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.runTestMethod(PowerMockJUnit44RunnerDelegateImpl.java:314)
at org.junit.internal.runners.MethodRoadie$2.run(MethodRoadie.java:86)
at org.junit.internal.runners.MethodRoadie.runBeforesThenTestThenAfters(MethodRoadie.java:94)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.executeTest(PowerMockJUnit44RunnerDelegateImpl.java:296)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner.executeTestInSuper(PowerMockJUnit47RunnerDelegateImpl.java:112)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner.executeTest(PowerMockJUnit47RunnerDelegateImpl.java:73)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.runBeforesThenTestThenAfters(PowerMockJUnit44RunnerDelegateImpl.java:284)
at org.junit.internal.runners.MethodRoadie.runTest(MethodRoadie.java:84)
at org.junit.internal.runners.MethodRoadie.run(MethodRoadie.java:49)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.invokeTestMethod(PowerMockJUnit44RunnerDelegateImpl.java:209)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.runMethods(PowerMockJUnit44RunnerDelegateImpl.java:148)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$1.run(PowerMockJUnit44RunnerDelegateImpl.java:122)
at org.junit.internal.runners.ClassRoadie.runUnprotected(ClassRoadie.java:34)
at org.junit.internal.runners.ClassRoadie.runProtected(ClassRoadie.java:44)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.run(PowerMockJUnit44RunnerDelegateImpl.java:120)
at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.run(JUnit4TestSuiteChunkerImpl.java:102)
at org.powermock.modules.junit4.common.internal.impl.AbstractCommonPowerMockRunner.run(AbstractCommonPowerMockRunner.java:53)
at org.powermock.modules.junit4.PowerMockRunner.run(PowerMockRunner.java:42)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

该程序没有模拟任何代码行，而是执行实际 MySQLConnect 函数中的代码。它正在使用实际的驱动程序。如果我从 @Test 中删除预期的部分，则测试成功。也就是说，不进行模拟，加载驱动程序和一切。

Answer 1

您不能使用 PowerMockito 或任何其他依赖运行时字节代码修改的模拟框架来模拟 java.lang.Class。这样做的原因是当 mockito 代理正在操纵(检测)应该模拟的类时，这些类已经加载。

你为什么不模拟你的 MysqlConnection 类？您可以在那里监视您的 MysqlConnect 方法并返回一个模拟连接。