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;
    }
}

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();
    }
}

错误的堆栈跟踪为：

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)

该程序不会模拟任何代码行，而是从实际的MySQLConnect函数执行代码。它正在利用实际的驱动程序。如果我从@Test中删除预期的部分，测试就会成功。也就是说，不做任何模拟，加载驱动程序等等。

Answer 1

你不能用 PowerMockito 或任何其他依赖于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 代理操作（检测）应该模拟的类时，这些类已经加载。

你为什么不嘲笑你的MysqlConnection课呢？在那里，您可以监视MysqlConnect方法并返回模拟连接。