我写了一个工厂来产生java.sql.Connection对象:

public class MySQLDatabaseConnectionFactory implements DatabaseConnectionFactory {

    @Override public Connection getConnection() {
        try {
            return DriverManager.getConnection(...);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }
}

我想验证传递给DriverManager的参数。getConnection,但我不知道如何模拟静态方法。我的测试用例使用JUnit 4和Mockito。是否有一个好的方法来模拟/验证这个特定的用例?


当前回答

我还编写了Mockito和AspectJ的组合:https://github.com/iirekm/varia/tree/develop/ajmock

你的例子是:

when(() -> DriverManager.getConnection(...)).thenReturn(...);

其他回答

我在《Mockito》中找到了一个解决方法。该特性仅在3.4.0版本中提供

https://asolntsev.github.io/en/2020/07/11/mockito-static-methods/

dependency In your build.gradle replace mockito-core:3.3.3 by mockito-inline:3.4.0: testImplementation('org.mockito:mockito-inline:3.4.0') what are we going to mock class Buddy { static String name() { return "John"; } } Mock the static method @Test void lookMomICanMockStaticMethods() { assertThat(Buddy.name()).isEqualTo("John"); try (MockedStatic<Buddy> theMock = Mockito.mockStatic(Buddy.class)) { theMock.when(Buddy::name).thenReturn("Rafael"); assertThat(Buddy.name()).isEqualTo("Rafael"); } assertThat(Buddy.name()).isEqualTo("John"); }

我想这对我们有帮助。

当您尝试模拟静态方法时,必须在try块中编写测试。因为重要的是要注意,作用域模拟必须由激活模拟的实体关闭。

      try (MockedStatic<Tester> tester = Mockito.mockStatic(Tester.class)) {
            tester.when(() -> Tester.testStatic("Testing..")).thenReturn(mock(ReturnObject.class));
    //Here you have to write the test cases
      }

在上面的例子中,我们必须模拟测试器类testStatic方法,输入参数为“Testing…”。在这里,该方法将返回一个ReturnObject类类型对象。因此我们写mockito当链像上面。

不要忘记在你的Gradle/maven中添加以下依赖项

    testImplementation 'org.mockito:mockito-inline:4.3.1'

稍微重构一下:

public class MySQLDatabaseConnectionFactory implements DatabaseConnectionFactory {
    ConnectionSupplier connectionSupplier = () -> SupplierDriverManager.getConnection();

    public void setConnSupplier(ConnectionSupplier supplier) {
        this.connectionSupplier = supplier;
    }

    @Override 
    public Connection getConnection() {
        try {
            return connectionSupplier.conn();
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }
    @FunctionalInterface
    interface ConnectionSupplier {
        Connection conn();
    }
}

然后你可以使用mockito:

MySQLDatabaseConnectionFactory.ConnectionSupplier connectionSupplier = mock(MySQLDatabaseConnectionFactory.ConnectionSupplier.class);
when(connectionSupplier.conn()).thenReturn(yourMockObject);
yourConnectionFactory.setConnSupplier(connectionSupplier);

你可以做一点重构:

public class MySQLDatabaseConnectionFactory implements DatabaseConnectionFactory {

    @Override public Connection getConnection() {
        try {
            return _getConnection(...some params...);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }

    //method to forward parameters, enabling mocking, extension, etc
    Connection _getConnection(...some params...) throws SQLException {
        return DriverManager.getConnection(...some params...);
    }
}

然后你可以扩展你的MySQLDatabaseConnectionFactory类来返回一个模拟的连接,对参数进行断言等等。

扩展类可以驻留在测试用例中,如果它位于相同的包中(我鼓励您这样做)

public class MockedConnectionFactory extends MySQLDatabaseConnectionFactory {

    Connection _getConnection(...some params...) throws SQLException {
        if (some param != something) throw new InvalidParameterException();

        //consider mocking some methods with when(yourMock.something()).thenReturn(value)
        return Mockito.mock(Connection.class);
    }
}

观察:当您在静态实体中调用静态方法时,您需要更改@PrepareForTest中的类。

例如:

securityAlgo = MessageDigest.getInstance(SECURITY_ALGORITHM);

对于上面的代码,如果您需要模拟MessageDigest类,请使用

@PrepareForTest(MessageDigest.class)

而如果你有如下内容:

public class CustomObjectRule {

    object = DatatypeConverter.printHexBinary(MessageDigest.getInstance(SECURITY_ALGORITHM)
             .digest(message.getBytes(ENCODING)));

}

然后,您需要准备这个代码所在的类。

@PrepareForTest(CustomObjectRule.class)

然后模拟这个方法:

PowerMockito.mockStatic(MessageDigest.class);
PowerMockito.when(MessageDigest.getInstance(Mockito.anyString()))
      .thenThrow(new RuntimeException());