Spring Boot测试自定义Filter时如何配置虚拟ApplicationContext解决配置缺失报错

你遇到的报错是因为当前项目没有被@SpringBootConfiguration标注的配置类（正式项目里通常就是带@SpringBootApplication注解的启动类，该注解默认继承了@SpringBootConfiguration），所以@SpringBootTest无法自动识别到配置来加载ApplicationContext。

另外注意你现有测试代码里的import org.springframework.mock.web.属于未完成的导入语句，需要先删除或补全，否则会先出现编译错误。

针对你仅需测试单个自定义Filter的场景，提供两种可行方案：

方案一：轻量手动构造MockMvc（推荐） #

不需要启动完整Spring上下文，直接手动注册Filter和虚拟测试接口即可完成测试，执行速度快、调试成本低：

package org.example.filters;

import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.springframework.http.MediaType;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.setup.MockMvcBuilders;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

public class LocaleFilterIntegrationTest {

  private MockMvc mvc;

  @BeforeEach
  void setUp() {
    // 实例化待测试的自定义Filter
    LocaleFilter localeFilter = new LocaleFilter();
    // 构造虚拟测试Controller，模拟业务接口接收请求
    TestController testController = new TestController();
    // 注册Filter和测试Controller到MockMvc，指定Filter拦截路径
    mvc = MockMvcBuilders.standaloneSetup(testController)
            .addFilter(localeFilter, "/*")
            .build();
  }

  @RestController
  static class TestController {
    @GetMapping("/")
    public String testEndpoint() {
      return "ok";
    }
  }

  @Test
  public void noLanguageShouldRedirectToSplash() throws Exception {
    mvc.perform(get("/").contentType(MediaType.TEXT_HTML)).andExpect(status().isOk());
  }
}

方案二：使用SpringBootTest加载上下文 #

如果需要依赖Spring上下文的其他能力，可以在测试类中添加内部配置类作为虚拟启动类：

package org.example.filters;

import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

// 指定测试用的配置类
@SpringBootTest(classes = LocaleFilterIntegrationTest.TestConfig.class)
@AutoConfigureMockMvc
public class LocaleFilterIntegrationTest {

  @Autowired
  private MockMvc mvc;

  // 测试用内部配置类，代替正式项目的启动类
  @Configuration
  static class TestConfig {
    // 注册自定义Filter到Spring上下文
    @Bean
    public LocaleFilter localeFilter() {
      return new LocaleFilter();
    }

    // 注册测试用Controller
    @Bean
    public TestController testController() {
      return new TestController();
    }
  }

  @RestController
  static class TestController {
    @GetMapping("/")
    public String testEndpoint() {
      return "ok";
    }
  }

  @Test
  public void noLanguageShouldRedirectToSplash() throws Exception {
    mvc.perform(get("/").contentType(MediaType.TEXT_HTML)).andExpect(status().isOk());
  }
}

内容的提问来源于stack exchange，提问作者errorline1