在UTDD的流程中，通常会从上到下进行模拟，流程如下：

Controller接口单元测试
–》Controller接口代码实现
–》Api接口单元测试
–》Api接口代码实现

那么我们先从Controller的单元测试模拟开始：
一、MockMvc功能介绍：
MockMvc是由spring-test包提供，实现了对Http请求的模拟，能够直接使用网络的形式，转换到Controller的调用，使得测试速度快、不依赖网络环境。同时提供了一套验证的工具，结果的验证十分方便。

接口MockMvcBuilder，提供一个唯一的build方法，用来构造MockMvc。
主要有两个实现：StandaloneMockMvcBuilder和DefaultMockMvcBuilder，分别对应两种测试方式，即独立安装和集成Web环境测试（并不会集成真正的web环境，而是通过相应的Mock API进行模拟测试，无须启动服务器）。
MockMvcBuilders提供了对应的创建方法standaloneSetup方法和webAppContextSetup方法，在使用时直接调用即可。

二、代码示例：
首先是pom坐标：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.5</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>loan-server</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>loan-server</name>
    <description>loan-server</description>
    <properties>
        <java.version>1.8</java.version>
        <testcontainers.version>1.16.0</testcontainers.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.24</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.jupiter</groupId>
                    <artifactId>junit-jupiter</artifactId>
                </exclusion>
            </exclusions>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.junit.vintage</groupId>
            <artifactId>junit-vintage-engine</artifactId>
            <scope>test</scope>
        </dependency>
        <!-- https://mvnrepository.com/artifact/junit/junit -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.jmockit/jmockit -->
        <dependency>
            <groupId>org.jmockit</groupId>
            <artifactId>jmockit</artifactId>
            <version>1.19</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <version>1.4.197</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.3.4</version>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.testcontainers</groupId>
                <artifactId>testcontainers-bom</artifactId>
                <version>${testcontainers.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

2.Controller接口测试类：

@RunWith(SpringRunner.class)
@AutoConfigureMockMvc
@SpringBootTest(classes = LoanServerApplication.class)//这里放启动类
public class LoanControllerTest {

    MockMvc mockMvc;
    @Autowired
    private WebApplicationContext webApplicationContext;

    @Before
    public void setUp() {
        mockMvc = MockMvcBuilders.webAppContextSetup(webApplicationContext)
                .addFilter(((request, response, chain) -> {
                    response.setCharacterEncoding("UTF-8");
                    chain.doFilter(request, response);
                })).build();
    }

        @Test
    public void should_get_userLoanPlan_success_byGet() throws Exception {
        String result = mockMvc.perform(
                get("/loan-plans/{idCard}", "412233333333"))
                .andExpect(status().isOk())
                .andReturn()
                .getResponse()
                .getContentAsString();
        String expected = "{\"createdAt\":\"2021-11-23T00:41:49.257479\",\"gender\":\"MALE\",\"houseMaterial\":{\"age\":0,\"price\":10000},\"id\":1,\"idCard\":\"412233333333\",\"income\":10000,\"lenderAge\":35,\"name\":\"王一\",\"togetherLender\":{\"idCard\":\"111111111\",\"income\":10000},\"updatedAt\":\"2021-11-23T00:41:49.257512\"}";
        JSONComparator comparator = new CustomComparator(JSONCompareMode.LENIENT,
                new Customization("id", (o1, o2) -> true),
                new Customization("createdAt", (o1, o2) -> true),
                new Customization("updatedAt", (o1, o2) -> true)
        );
        JSONAssert.assertEquals(expected, result, comparator);
    }

    @Test
    public void should_get_userLoanPlan_success_byPost() throws Exception {
        String result = mockMvc.perform(
                post("/loan-plans/{idCard}", "412233333333"))
                .andExpect(status().isOk())
                .andReturn()
                .getResponse()
                .getContentAsString();
        String expected = "{\"createdAt\":\"2021-11-23T00:41:49.257479\",\"gender\":\"MALE\",\"houseMaterial\":{\"age\":0,\"price\":10000},\"id\":1,\"idCard\":\"412233333333\",\"income\":10000,\"lenderAge\":35,\"name\":\"王一\",\"togetherLender\":{\"idCard\":\"111111111\",\"income\":10000},\"updatedAt\":\"2021-11-23T00:41:49.257512\"}";
        JSONComparator comparator = new CustomComparator(JSONCompareMode.LENIENT,
                new Customization("id", (o1, o2) -> true),
                new Customization("createdAt", (o1, o2) -> true),
                new Customization("updatedAt", (o1, o2) -> true)
        );
        JSONAssert.assertEquals(expected, result, comparator);
    }
 }

3、Controller接口代码

@RestController
@RequestMapping("loan-plans")
public class LoanController {
    

    @GetMapping("/{idCard}")
    public JSONObject getUserLoadPlanMaterial(@PathVariable String idCard) {
        String result = "{\"createdAt\":\"2021-10-23T00:41:49.257479\",\"gender\":\"MALE\",\"houseMaterial\":{\"age\":0,\"price\":10000},\"id\":1,\"idCard\":\"412233333333\",\"income\":10000,\"lenderAge\":35,\"name\":\"王一\",\"togetherLender\":{\"idCard\":\"111111111\",\"income\":10000},\"updatedAt\":\"2021-10-23T00:41:49.257512\"}";

        return JSONObject.parseObject(result);
    }
  
  @PostMapping("/{idCard}")
    public JSONObject Test(@PathVariable String idCard) {
        String result = "{\"createdAt\":\"2021-10-23T00:41:49.257479\",\"gender\":\"MALE\",\"houseMaterial\":{\"age\":0,\"price\":10000},\"id\":1,\"idCard\":\"412233333333\",\"income\":10000,\"lenderAge\":35,\"name\":\"王一\",\"togetherLender\":{\"idCard\":\"111111111\",\"income\":10000},\"updatedAt\":\"2021-10-23T00:41:49.257512\"}";
        return JSONObject.parseObject(result);
    }
 }

这里我们通过MockMvc实现了一个简单的get/post请求接口的模拟及单元测试的编写~ 有兴趣的可以尝试一下~ 还可以拓展一些其他接口的单元测试~

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