非构造注入方式下Mock Service的JUnit测试问题解决

我明白你的痛点——用字段注入（@Autowired直接标注在字段上）时，Mockito默认不会自动帮你注入Mock对象，所以才会出现riskFilterService始终为null的情况。不用改成构造注入的话，有两种常用的解决方式，我给你详细说明：

方法一：使用Mockito的@Mock和@InjectMocks注解 #

这是最常用的方式，通过注解让Mockito自动完成Mock依赖的注入：

1. 在测试类中，给需要Mock的依赖（RiskFilterService）标注@Mock注解
2. 给待测试的服务类（BinCountryCheckFilterImpl）标注@InjectMocks注解
3. 在测试方法执行前，调用MockitoAnnotations.openMocks(this)初始化这些注解

对应的测试类代码：

import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import java.util.ArrayList;
import static org.mockito.BDDMockito.*;

public class BinCountryCheckFilterImplTest {

    // 标注要Mock的依赖对象
    @Mock
    private RiskFilterService riskFilterService;

    // 标注待测试的服务，Mockito会自动把@Mock的对象注入到这里的字段中
    @InjectMocks
    private BinCountryCheckFilterImpl binCountryCheckFilterImpl;

    // 初始化Mockito注解
    @BeforeEach
    void setUp() {
        MockitoAnnotations.openMocks(this);
    }

    @Test
    public void testValidateBinCountryCheckFilter() throws JAXBException, JsonProcessingException {
        // Arrange
        Merchants merchant = mock(Merchants.class);
        Contracts contract = mock(Contracts.class);
        Terminals terminal = mock(Terminals.class);
        PaymentTransaction message = mock(PaymentTransaction.class);
        HttpServletRequest request = mock(HttpServletRequest.class);

        int expectedTerminalId = 11;
        String expectedFilterType = "BinCountryCheckFilter";
        given(terminal.getId()).willReturn(expectedTerminalId);
        given(riskFilterService.findRiskFiltersByTerminalIdAndType(expectedTerminalId, expectedFilterType))
                .willReturn(new ArrayList<>()); // 替换成你需要的测试数据

        // Act
        binCountryCheckFilterImpl.validateBinCountryCheckFilter(merchant, contract, terminal, message, request);

        // Assert
        then(riskFilterService)
                .should()
                .findRiskFiltersByTerminalIdAndType(expectedTerminalId, expectedFilterType);
    }
}

方法二：手动调用Mockito.injectMocks()注入 #

如果不想用注解，也可以手动初始化Mock对象，然后调用Mockito.injectMocks()把Mock注入到待测试服务的字段中：

import org.junit.jupiter.api.Test;
import java.util.ArrayList;
import static org.mockito.BDDMockito.*;

public class BinCountryCheckFilterImplTest {

    @Test
    public void testValidateBinCountryCheckFilter() throws JAXBException, JsonProcessingException {
        // Arrange
        RiskFilterService riskFilterService = mock(RiskFilterService.class);
        BinCountryCheckFilterImpl binCountryCheckFilterImpl = new BinCountryCheckFilterImpl();

        // 手动将Mock对象注入到服务的字段中
        org.mockito.Mockito.injectMocks(binCountryCheckFilterImpl);

        Merchants merchant = mock(Merchants.class);
        Contracts contract = mock(Contracts.class);
        Terminals terminal = mock(Terminals.class);
        PaymentTransaction message = mock(PaymentTransaction.class);
        HttpServletRequest request = mock(HttpServletRequest.class);

        int expectedTerminalId = 11;
        String expectedFilterType = "BinCountryCheckFilter";
        given(terminal.getId()).willReturn(expectedTerminalId);
        given(riskFilterService.findRiskFiltersByTerminalIdAndType(expectedTerminalId, expectedFilterType))
                .willReturn(new ArrayList<>());

        // Act
        binCountryCheckFilterImpl.validateBinCountryCheckFilter(merchant, contract, terminal, message, request);

        // Assert
        then(riskFilterService)
                .should()
                .findRiskFiltersByTerminalIdAndType(expectedTerminalId, expectedFilterType);
    }
}

补充说明 #

两种方式的核心都是让Mockito帮你把Mock对象注入到服务类的私有字段中——因为字段注入没有暴露构造器，所以需要Mockito的额外支持。这两种方案都不需要修改原服务类的代码，完全满足你“不使用构造注入”的要求。

内容的提问来源于stack exchange，提问作者Peter Penzov