Rest Assured

Rest Assured is a popular Java library used for testing and validating RESTful APIs. It simplifies writing tests for REST services by providing an easy-to-use syntax, allowing developers to send HTTP requests and verify the responses without writing a lot of boilerplate code.

• Simplified HTTP request handling: Rest Assured allows you to perform all common HTTP methods (GET, POST, PUT, DELETE, etc.) in a simple, readable syntax.
• Built-in validation methods: It provides built-in methods for validating response data like status codes, headers, body content, etc., using a BDD (Behavior-Driven Development)-style approach.
• Integration with testing frameworks: Rest Assured integrates easily with popular testing frameworks like JUnit and TestNG, making it seamless to write API tests alongside unit tests.

1. Ease of Use: Testing REST APIs without Rest Assured can involve writing significant boilerplate code using libraries like HttpURLConnection or HttpClient. Rest Assured abstracts away much of this complexity.

2. Readable and Maintainable Tests: The DSL (Domain-Specific Language) used in Rest Assured makes the test cases more readable and easier to maintain. For example using the Gherkin Syntax with Rest Assured:

    @Test
    void create()
    {
        Hotel h3 = new Hotel("Cab-inn", "Østergade 2", Hotel.HotelType.BUDGET);
        Room r1 = new Room(117, new BigDecimal(4500), Room.RoomType.SINGLE);
        Room r2 = new Room(118, new BigDecimal(2300), Room.RoomType.DOUBLE);
        h3.addRoom(r1);
        h3.addRoom(r2);
        HotelDto newHotel = new HotelDto(h3);
   
        List<RoomDto> roomDtos =
        given()
                .contentType(ContentType.JSON)
                .body(newHotel)
                .when()
                .post(BASE_URL + "/hotels")
                .then()
                .statusCode(201)
                .body("id", equalTo(3))
                .body("hotelName", equalTo("Cab-inn"))
                .body("hotelAddress", equalTo("Østergade 2"))
                .body("hotelType", equalTo("BUDGET"))
                .body("rooms", hasSize(2))
                .extract().body().jsonPath().getList("rooms", RoomDto.class);
   
        assertThat(roomDtos, containsInAnyOrder(new RoomDto(r1), new RoomDto(r2)));
    }
   

3. Comprehensive API Testing: Rest Assured supports a wide range of features like:

   • Authentication (Basic, OAuth)
   • JSON/XML response validation
   • Multi-part form data testing
   • Request/Response logging for debugging

4. Integration and Automation: It helps automate API tests in CI/CD pipelines, ensuring that any changes to the API are quickly caught, which is crucial for maintaining the health of modern microservices-based architectures.

In summary, Rest Assured is widely used because it makes testing RESTful APIs simple, readable, and maintainable, which is especially valuable in projects that involve continuous integration and automated testing.

    private static ApplicationConfig appConfig;
    private static final String BASE_URL = "http://localhost:7777/api";
    private static EntityManagerFactory emfTest;
    private static ObjectMapper jsonMapper = new ObjectMapper();

    private static String securityToken;
    private Map<String, IJPAEntity> entities; // find an entity by its name (e.g. "person1")

    @BeforeAll
    static void setUpAll() {
        RestAssured.baseURI = BASE_URL;
        jsonMapper.findAndRegisterModules(); // needed with pom dependency for jackson to use java 8 LocalDate: https://mkyong.com/java/jackson-java-8-date-time-type-java-time-localdate-not-supported-by-default/

        HibernateConfig.setTestMode(true); // IMPORTANT leave this at the very top of this method in order to use the test database
        RestRoutes restRoutes = new RestRoutes();

        // Setup test database using docker testcontainers
        emfTest = HibernateConfig.getEntityManagerFactory();

        // Start server
        appConfig = ApplicationConfig.
                getInstance()
                .initiateServer()
                .checkSecurityRoles()
//                .setErrorHandling() // This one overrules the setApiExeptionHandling
                .setGeneralExceptionHandling()
                .setRoute(restRoutes.getOpenRoutes())
                .setRoute(SecurityRoutes.getSecurityRoutes())
                .setRoute(SecurityRoutes.getSecuredRoutes())
                .setRoute(restRoutes.personEntityRoutes) // A different way to get the EndpointGroup. Getting data from DB
                .setCORS()
                .setApiExceptionHandling()
                .startServer(7777)
        ;
    }

    @AfterAll
    static void afterAll() {
        HibernateConfig.setTestMode(false);
        appConfig.stopServer();
    }

    @BeforeEach
    void setUpEach() {
        // Setup test database for each test
        new TestUtils().createUsersAndRoles(emfTest);
        // Setup DB Persons and Addresses
        entities = new TestUtils().createPersonEntities(emfTest);
    }

For the full code see: https://gist.github.com/Thomas-Hartmann/670b5f41edb818ed47acde565f6fb1a8#file-personressourcetest-java