如何为指定的meetsPreconditions业务方法编写JUnit测试用例

该测试用例覆盖了meetsPreconditions方法的所有逻辑分支，通过Mock依赖组件解耦外部依赖，无需依赖真实业务数据即可完成单元测试。

前置依赖 #

需要在pom.xml（Maven）或build.gradle（Gradle）中引入JUnit 5和Mockito的依赖，示例Maven依赖如下：

<dependency>
    <groupId>org.junit.jupiter</groupId>
    <artifactId>junit-jupiter-api</artifactId>
    <version>5.9.2</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.mockito</groupId>
    <artifactId>mockito-core</artifactId>
    <version>4.11.0</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.mockito</groupId>
    <artifactId>mockito-junit-jupiter</artifactId>
    <version>4.11.0</version>
    <scope>test</scope>
</dependency>

测试用例代码 #

import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.Spy;
import org.mockito.junit.jupiter.MockitoExtension;
import java.util.List;
import static org.junit.jupiter.api.Assertions.*;
import static org.mockito.ArgumentMatchers.*;
import static org.mockito.Mockito.*;

@ExtendWith(MockitoExtension.class)
public class YourTargetClassTest { // 替换为你实际的业务类名

    @Mock
    private Model model; // 替换为你项目中实际的Model类名
    @Mock
    private Toolkit toolkit; // 替换为你项目中实际的Toolkit类名
    @Mock
    private DictionaryTools dictionaryTools;
    @Mock
    private LineFeature lineFeature;
    @Mock
    private DictionaryRangeItem formOfWayItem;
    @Mock
    private RoadElementsChain roadElementsChain;

    // 要测试的目标类，用Spy以便Mock内部调用的createRoadElementsChainBuilder方法
    @Spy
    @InjectMocks
    private YourTargetClass target; // 替换为你实际的业务类名

    @Test
    void meetsPreconditions_FormOfWayNotSmallSlipRoad_ReturnFalse() {
        // 构造FormOfWay不是SmallSlipRoad的场景
        when(model.RANGES.FormOfWay.SmallSlipRoad).thenReturn("SMALL_SLIP_ROAD");
        when(toolkit.getDictionaryTools()).thenReturn(dictionaryTools);
        when(dictionaryTools.getAttributeFromFeature(eq(lineFeature), any(), eq(DictionaryRangeItem.class)))
                .thenReturn(formOfWayItem);
        when(formOfWayItem.getValue()).thenReturn("NORMAL_ROAD");

        boolean result = target.meetsPreconditions(lineFeature);

        assertFalse(result);
        // 验证不会进入链条构建逻辑
        verify(target, never()).createRoadElementsChainBuilder();
    }

    @Test
    void meetsPreconditions_LineFeaturesEmpty_ReturnFalse() {
        when(model.RANGES.FormOfWay.SmallSlipRoad).thenReturn("SMALL_SLIP_ROAD");
        when(toolkit.getDictionaryTools()).thenReturn(dictionaryTools);
        when(dictionaryTools.getAttributeFromFeature(eq(lineFeature), any(), eq(DictionaryRangeItem.class)))
                .thenReturn(formOfWayItem);
        when(formOfWayItem.getValue()).thenReturn("SMALL_SLIP_ROAD");
        when(target.createRoadElementsChainBuilder()).thenReturn(roadElementsChain);
        when(roadElementsChain.getLineFeatures()).thenReturn(List.of());

        boolean result = target.meetsPreconditions(lineFeature);

        assertFalse(result);
        // 验证不会设置道路链条属性
        verify(target, never()).setChainOfRoads(any());
    }

    @Test
    void meetsPreconditions_StartFeaturesCountLessThan2_ReturnFalse() {
        when(model.RANGES.FormOfWay.SmallSlipRoad).thenReturn("SMALL_SLIP_ROAD");
        when(toolkit.getDictionaryTools()).thenReturn(dictionaryTools);
        when(dictionaryTools.getAttributeFromFeature(eq(lineFeature), any(), eq(DictionaryRangeItem.class)))
                .thenReturn(formOfWayItem);
        when(formOfWayItem.getValue()).thenReturn("SMALL_SLIP_ROAD");
        when(target.createRoadElementsChainBuilder()).thenReturn(roadElementsChain);
        when(roadElementsChain.getLineFeatures()).thenReturn(List.of(lineFeature));
        when(roadElementsChain.getOtherLineFeaturesAtStart()).thenReturn(List.of(lineFeature)); // 数量为1，不满足>1的要求
        when(roadElementsChain.getOtherLineFeaturesAtEnd()).thenReturn(List.of(lineFeature, lineFeature));

        boolean result = target.meetsPreconditions(lineFeature);

        assertFalse(result);
        verify(target, never()).setChainOfRoads(any());
    }

    @Test
    void meetsPreconditions_EndFeaturesCountLessThan2_ReturnFalse() {
        when(model.RANGES.FormOfWay.SmallSlipRoad).thenReturn("SMALL_SLIP_ROAD");
        when(toolkit.getDictionaryTools()).thenReturn(dictionaryTools);
        when(dictionaryTools.getAttributeFromFeature(eq(lineFeature), any(), eq(DictionaryRangeItem.class)))
                .thenReturn(formOfWayItem);
        when(formOfWayItem.getValue()).thenReturn("SMALL_SLIP_ROAD");
        when(target.createRoadElementsChainBuilder()).thenReturn(roadElementsChain);
        when(roadElementsChain.getLineFeatures()).thenReturn(List.of(lineFeature));
        when(roadElementsChain.getOtherLineFeaturesAtStart()).thenReturn(List.of(lineFeature, lineFeature));
        when(roadElementsChain.getOtherLineFeaturesAtEnd()).thenReturn(List.of(lineFeature)); // 数量为1，不满足>1的要求

        boolean result = target.meetsPreconditions(lineFeature);

        assertFalse(result);
        verify(target, never()).setChainOfRoads(any());
    }

    @Test
    void meetsPreconditions_AllConditionsMatch_ReturnTrueAndSetChain() {
        when(model.RANGES.FormOfWay.SmallSlipRoad).thenReturn("SMALL_SLIP_ROAD");
        when(toolkit.getDictionaryTools()).thenReturn(dictionaryTools);
        when(dictionaryTools.getAttributeFromFeature(eq(lineFeature), any(), eq(DictionaryRangeItem.class)))
                .thenReturn(formOfWayItem);
        when(formOfWayItem.getValue()).thenReturn("SMALL_SLIP_ROAD");
        when(target.createRoadElementsChainBuilder()).thenReturn(roadElementsChain);
        when(roadElementsChain.getLineFeatures()).thenReturn(List.of(lineFeature));
        when(roadElementsChain.getOtherLineFeaturesAtStart()).thenReturn(List.of(lineFeature, lineFeature));
        when(roadElementsChain.getOtherLineFeaturesAtEnd()).thenReturn(List.of(lineFeature, lineFeature));

        boolean result = target.meetsPreconditions(lineFeature);

        assertTrue(result);
        // 验证链条构建和属性设置逻辑正常执行
        verify(roadElementsChain, times(1)).buildRoadElementsChain(lineFeature);
        verify(target, times(1)).setChainOfRoads(roadElementsChain);
    }
}

使用时将代码中占位的类名替换为你项目中对应的实际类名即可，如果model.RANGES.FormOfWay.SmallSlipRoad的返回值类型不是字符串，对应调整Mock返回值的类型即可。

内容的提问来源于stack exchange，提问作者deepankar gautam