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);

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'

对于模仿静态函数，我能够这样做:

在helper类/对象中创建一个包装器函数。(使用名称变体可能有助于保持内容的分离和可维护。) 在代码中使用此包装器。(是的，代码的实现需要考虑到测试。) 模拟包装器函数。

包装器代码片段(不是真正的功能，只是为了说明)

class myWrapperClass ...
    def myWrapperFunction (...) {
        return theOriginalFunction (...)
    }

当然，在一个包装器类中积累多个这样的函数可能有利于代码重用。

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);
    }
}

在Mockito之上使用PowerMockito。

示例代码:

@RunWith(PowerMockRunner.class)
@PrepareForTest(DriverManager.class)
public class Mocker {

    @Test
    public void shouldVerifyParameters() throws Exception {

        //given
        PowerMockito.mockStatic(DriverManager.class);
        BDDMockito.given(DriverManager.getConnection(...)).willReturn(...);

        //when
        sut.execute(); // System Under Test (sut)

        //then
        PowerMockito.verifyStatic();
        DriverManager.getConnection(...);

    }

更多信息:

为什么Mockito不模拟静态方法?

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);