REST Assured - Quick Reference

Deep Knowledge: Use mcp__documentation__fetch_docs with technology: rest-assured for comprehensive documentation.

When NOT to Use This Skill

Unit Tests - Use junit with Mockito for isolated tests
E2E Browser Tests - Use Selenium or Playwright
WebSocket Testing - Use dedicated WebSocket testing tools
Non-Java Projects - Use language-specific HTTP clients
GraphQL APIs - Consider GraphQL-specific testing tools

Pattern Essenziali

GET Request

given()
    .baseUri("http://localhost:8080")
    .contentType("application/json")
.when()
    .get("/api/v1/users/1")
.then()
    .statusCode(200)
    .body("name", equalTo("John"));

POST Request

given()
    .contentType("application/json")
    .body("""
        {"name": "John", "email": "john@example.com"}
        """)
.when()
    .post("/api/v1/users")
.then()
    .statusCode(201)
    .body("id", notNullValue());

Spring Boot Integration

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
class UserApiTest {
    @LocalServerPort
    private int port;

    @BeforeEach
    void setUp() {
        RestAssured.port = port;
    }

    @Test
    void shouldGetUsers() {
        given()
        .when().get("/api/v1/users")
        .then().statusCode(200);
    }
}

Authentication

// Bearer Token
given().header("Authorization", "Bearer " + token)

// Basic Auth
given().auth().basic("user", "pass")

Hamcrest Matchers Comuni

Matcher	Uso
`equalTo(value)`	Exact match
`notNullValue()`	Not null
`hasSize(n)`	Collection size
`containsString(str)`	String contains

Anti-Patterns

Anti-Pattern	Why It's Bad	Solution
Hardcoding base URI	Not portable across environments	Use RestAssured.baseURI or config
Not setting contentType	Request may fail or be misinterpreted	Always set contentType for POST/PUT
Ignoring status codes	Silent failures	Always assert status code
Not using path parameters	Hard to read, error-prone	Use {id} placeholders
Testing too much in one test	Hard to debug	One endpoint/scenario per test
No authentication testing	Security gaps	Test auth headers, tokens
Not validating response schema	API contract violations	Use JSON schema validation

Quick Troubleshooting

Problem	Likely Cause	Solution
"Connection refused"	Server not running	Start server, verify port
"Expected status 200 but was 500"	API error or wrong request	Check server logs, validate request body
"Cannot deserialize JSON"	Wrong content type or body format	Verify Content-Type header, check JSON
Authentication fails	Missing/wrong token	Check Authorization header
Timeout	Slow API or network issue	Increase timeout or investigate performance
"Path not found"	Wrong URL or method	Verify endpoint exists, check HTTP method

Reference Documentation

REST Assured Docs