feat: add spring-boot-testing skill for Spring Boot 4.0 (#1085)

- Introduced MockMvcTester for AssertJ-style assertions in Spring MVC testing. - Added @RestClientTest for testing REST clients with MockRestServiceServer. - Implemented RestTestClient as a modern alternative to TestRestTemplate. - Documented migration steps from Spring Boot 3.x to 4.0, including dependency and annotation changes. - Created an overview of test slices to guide testing strategies. - Included Testcontainers setup for JDBC testing with PostgreSQL and MySQL. - Enhanced @WebMvcTest documentation with examples for various HTTP methods and validation.
2026-03-20 16:15:12 +00:00 · 2026-03-20 04:54:37 +05:30
parent ee71c0689c
commit e4fc57f204
16 changed files with 3171 additions and 0 deletions
--- a/skills/spring-boot-testing/references/restclienttest.md
+++ b/skills/spring-boot-testing/references/restclienttest.md
@@ -0,0 +1,227 @@
+# @RestClientTest
+
+Testing REST clients in isolation with MockRestServiceServer.
+
+## Overview
+
+`@RestClientTest` auto-configures:
+
+- RestTemplate/RestClient with mock server support
+- Jackson ObjectMapper
+- MockRestServiceServer
+
+## Basic Setup
+
+```java
+@RestClientTest(WeatherService.class)
+class WeatherServiceTest {
+  
+  @Autowired
+  private WeatherService weatherService;
+  
+  @Autowired
+  private MockRestServiceServer server;
+}
+```
+
+## Testing RestTemplate
+
+```java
+@RestClientTest(WeatherService.class)
+class WeatherServiceTest {
+  
+  @Autowired
+  private WeatherService weatherService;
+  
+  @Autowired
+  private MockRestServiceServer server;
+  
+  @Test
+  void shouldFetchWeather() {
+    // Given
+    server.expect(requestTo("https://api.weather.com/v1/current"))
+      .andExpect(method(HttpMethod.GET))
+      .andExpect(queryParam("city", "Berlin"))
+      .andRespond(withSuccess()
+        .contentType(MediaType.APPLICATION_JSON)
+        .body("{\"temperature\": 22, \"condition\": \"Sunny\"}"));
+    
+    // When
+    Weather weather = weatherService.getCurrentWeather("Berlin");
+    
+    // Then
+    assertThat(weather.getTemperature()).isEqualTo(22);
+    assertThat(weather.getCondition()).isEqualTo("Sunny");
+  }
+}
+```
+
+## Testing RestClient (Spring 6.1+)
+
+```java
+@RestClientTest(WeatherService.class)
+class WeatherServiceTest {
+  
+  @Autowired
+  private WeatherService weatherService;
+  
+  @Autowired
+  private MockRestServiceServer server;
+  
+  @Test
+  void shouldFetchWeatherWithRestClient() {
+    server.expect(requestTo("https://api.weather.com/v1/current"))
+      .andRespond(withSuccess()
+        .body("{\"temperature\": 22}"));
+    
+    Weather weather = weatherService.getCurrentWeather("Berlin");
+    
+    assertThat(weather.getTemperature()).isEqualTo(22);
+  }
+}
+```
+
+## Request Matching
+
+### Exact URL
+
+```java
+server.expect(requestTo("https://api.example.com/users/1"))
+  .andRespond(withSuccess());
+```
+
+### URL Pattern
+
+```java
+server.expect(requestTo(matchesPattern("https://api.example.com/users/\\d+")))
+  .andRespond(withSuccess());
+```
+
+### HTTP Method
+
+```java
+server.expect(ExpectedCount.once(), 
+  requestTo("https://api.example.com/users"))
+  .andExpect(method(HttpMethod.POST))
+  .andRespond(withCreatedEntity(URI.create("/users/1")));
+```
+
+### Request Body
+
+```java
+server.expect(requestTo("https://api.example.com/users"))
+  .andExpect(content().contentType(MediaType.APPLICATION_JSON))
+  .andExpect(content().json("{\"name\": \"John\"}"))
+  .andRespond(withSuccess());
+```
+
+### Headers
+
+```java
+server.expect(requestTo("https://api.example.com/users"))
+  .andExpect(header("Authorization", "Bearer token123"))
+  .andExpect(header("X-Api-Key", "secret"))
+  .andRespond(withSuccess());
+```
+
+## Response Types
+
+### Success with Body
+
+```java
+server.expect(requestTo("/users/1"))
+  .andRespond(withSuccess()
+    .contentType(MediaType.APPLICATION_JSON)
+    .body("{\"id\": 1, \"name\": \"John\"}"));
+```
+
+### Success from Resource
+
+```java
+server.expect(requestTo("/users/1"))
+  .andRespond(withSuccess()
+    .body(new ClassPathResource("user-response.json")));
+```
+
+### Created
+
+```java
+server.expect(requestTo("/users"))
+  .andExpect(method(HttpMethod.POST))
+  .andRespond(withCreatedEntity(URI.create("/users/1")));
+```
+
+### Error Response
+
+```java
+server.expect(requestTo("/users/999"))
+  .andRespond(withResourceNotFound());
+
+server.expect(requestTo("/users"))
+  .andRespond(withServerError()
+    .body("Internal Server Error"));
+
+server.expect(requestTo("/users"))
+  .andRespond(withStatus(HttpStatus.BAD_REQUEST)
+    .body("{\"error\": \"Invalid input\"}"));
+```
+
+## Verifying Requests
+
+```java
+@Test
+void shouldCallApi() {
+  server.expect(ExpectedCount.once(), 
+    requestTo("https://api.example.com/data"))
+    .andRespond(withSuccess());
+  
+  service.fetchData();
+  
+  server.verify(); // Verify all expectations met
+}
+```
+
+## Ignoring Extra Requests
+
+```java
+@Test
+void shouldHandleMultipleCalls() {
+  server.expect(ExpectedCount.manyTimes(),
+    requestTo(matchesPattern("/api/.*")))
+    .andRespond(withSuccess());
+  
+  // Multiple calls allowed
+  service.callApi();
+  service.callApi();
+  service.callApi();
+}
+```
+
+## Reset Between Tests
+
+```java
+@BeforeEach
+void setUp() {
+  server.reset();
+}
+```
+
+## Testing Timeouts
+
+```java
+server.expect(requestTo("/slow-endpoint"))
+  .andRespond(withSuccess()
+    .body("{\"data\": \"test\"}")
+    .delay(100, TimeUnit.MILLISECONDS));
+
+// Test timeout handling
+```
+
+## Best Practices
+
+1. Always verify `server.verify()` at end of test
+2. Use resource files for large JSON responses
+3. Match on minimal set of request attributes
+4. Reset server in @BeforeEach
+5. Test error responses, not just success
+6. Verify request body for POST/PUT calls