Rest Assured Advanced Interview Questions with Answers

If an API accepts XML but returns JSON, how do you handle this in Rest Assured?

We can use the .accept() method to specify the content type that the API accepts and the .contentType() method to specify the content type that the API returns. Here is an example:

given()
    .accept(ContentType.XML)
    .contentType(ContentType.JSON)
    .get("/api/users")
.then()
    .statusCode(200);

In this example, we are specifying that the API accepts XML and returns JSON.

How to provide custom Serializers and Deserializers in Rest Assured?

To provide custom Serializers and Deserializers in Rest Assured, we can use the .register() method. Here is an example:

RestAssured.config = RestAssured.config().objectMapperConfig(new ObjectMapperConfig().jackson2ObjectMapperFactory((cls, charset) -> {
    ObjectMapper objectMapper = new ObjectMapper();
    SimpleModule module = new SimpleModule();
    module.addSerializer(new CustomSerializer());
    module.addDeserializer(new CustomDeserializer());
    objectMapper.registerModule(module);
    return objectMapper;
}));

In this example, we are registering a custom Serializer and Deserializer for the ObjectMapper.

What are the important classes in Rest Assured?

Some of the important classes in Rest Assured are:

RestAssured: Main entry point for using Rest Assured.
RequestSpecBuilder: Used to build the request specification.
Response: Represents the response of an API request.
Matchers: Provides methods for validating responses.
JsonPath: Used to parse JSON responses.
XmlPath: Used to parse XML responses.

How can we upload files using Rest Assured?

To upload files using Rest Assured, we can use the .multiPart() method. Here is an example of how to upload a file

given()
    .multiPart(new File("file.txt"))
.when()
    .post("/upload")
.then()
    .statusCode(200);

In this example, we are uploading a file named file.txt using a POST request to the /upload endpoint.

How to log request and response details in Rest Assured?

To log request and response details in Rest Assured, we can use the .log() method. Here is an example:

given()
    .log().all()
    .get("/api/users")
.then()
    .log().all();

This will log the request and response details to the console.

How we can pass Bearer token to all requests in Rest Assured?

To pass a Bearer token to all requests in Rest Assured, we can use the .auth().oauth2() method. Here is an example:

given()
    .auth().oauth2("Bearer token")
    .get("/api/users")
.then()
    .statusCode(200);

This will pass the Bearer token to all requests made by the given() method.

Why do we use filters in Rest Assured?

Filters in Rest Assured are used to modify the request or response before or after it is sent or received. Some common use cases for filters are:

Custom Authentication: Implement custom authentication logic.
Logging: Log request and response details.
Error Handling: Handle errors in the response.

What are the scenarios where you used redirects in your project?

Some scenarios where we use redirects in a project are:

Authentication: Redirect requests to an authentication server. While using oauth2 authentication, we may need to redirect requests to the authorization server, in that case, we can use redirects.
API Versioning: Redirect requests to different API versions. We can use redirects to redirect requests to different versions of the API based on the version specified in the request.
Load Balancing: Redirect requests to different servers based on load. We can use redirects to redirect requests to different servers based on the load on each server to do the load testing.

How do you set up Rest Assured in a Maven project?

To set up Rest Assured in a Maven project, we need to add the following dependency to our pom.xml file:

<dependency>
    <groupId>io.rest-assured</groupId>
    <artifactId>rest-assured</artifactId>
    <version>4.4.0</version>
    <scope>test</scope>
</dependency>

This will download the Rest Assured library and its dependencies when you build your project using Maven.

How do you convert postman requests to Rest Assured code?

We can convert Postman requests to Rest Assured code by following these steps:

Hit the request in Postman.
Click on the Code button in the top right corner.
Select the Java language from the dropdown.
Copy the generated Rest Assured code and paste it into your Java project.

How do we validate the response against JSON schema?

To validate the response against a JSON schema in Rest Assured, we can use the matchesJsonSchemaInClasspath() method. Here is an example:

given()
    .get("/api/users")
.then()
    .assertThat()
    .body(matchesJsonSchemaInClasspath("schema.json"));

In this example, we are validating the response of a GET request against a JSON schema file named schema.json.

How to work with cookies in Rest Assured?

Rest Assured provides methods to handle cookies in API requests. Some of the common methods are:

Adding Cookies: Use the .cookie() method to add cookies to the request.
Getting Cookies: Use the .getCookies() method to get all the cookies from the response.
Validating Cookies: Use the .cookie() method with Matchers to validate cookies in the response.

How do you handle file downloads in Rest Assured?

Rest Assured provides methods to handle file downloads in API requests. Some of the common methods are:

Downloading Files: Use the .getBody().asInputStream() method to download files from the response.
Validating File Downloads: Use the .getBody().asInputStream() method with Matchers to validate file downloads in the response.

How do you handle SSL certificates in Rest Assured?

Rest Assured provides methods to handle SSL certificates in API requests. Some of the common methods are:

Ignoring SSL Certificates: Use the .relaxedHTTPSValidation() method to ignore SSL certificates.
Validating SSL Certificates: Use the .keyStore() method to validate SSL certificates.

What are the custom configurations that can be set in Rest Assured?

Some of the custom configurations that can be set in Rest Assured are:

Connection Timeout: Set the connection timeout using the .config(RestAssuredConfig.config().httpClient(HttpClientConfig.httpClientConfig().setParam("http.connection.timeout", timeout))) method.
Socket Timeout: Set the socket timeout using the .config(RestAssuredConfig.config().httpClient(HttpClientConfig.httpClientConfig().setParam("http.socket.timeout", timeout))) method.
Proxy Configuration: Set the proxy configuration using the .config(RestAssuredConfig.config().httpClient(HttpClientConfig.httpClientConfig().setProxy("proxyHost", proxyPort))) method.
Redirects: Set the redirects configuration using the .redirects().follow(true) method.

How do you handle response parsing in Rest Assured?

Rest Assured provides methods to handle response parsing in API requests. Some of the common methods are:

Parsing JSON Response: Use the .jsonPath() method to parse JSON response.
Parsing XML Response: Use the .xmlPath() method to parse XML response.

How do you integrate Rest Assured with TestNG?

Rest Assured can be integrated with TestNG for better test organization and execution. Some key points are:

TestNG Annotations: Use TestNG annotations like @Test, @BeforeTest, @AfterTest for test organization.
Test Dependencies: Define test dependencies using @Test(dependsOnMethods) for sequential execution.
Test Groups: Group related tests using @Test(groups) for better management.
Parallel Execution: Configure parallel test execution in testng.xml file.

How do you handle dynamic request payloads in Rest Assured?

Rest Assured allows you to handle dynamic request payloads using various methods. Some of the common methods are:

Using Maps: Create a map of key-value pairs and pass it to the .body() method.
Using POJOs: Create a Plain Old Java Object (POJO) and pass it to the .body() method.
Using JSON Strings: Create a JSON string and pass it to the .body() method.

How do you handle concurrent API requests in Rest Assured?

Rest Assured can handle concurrent requests using:

ThreadLocal: Maintain thread-safe request specifications
Parallel Test Execution: Use TestNG parallel execution
Connection Pooling: Configure HTTP client connection pools

How do you handle API mocking in Rest Assured?

Rest Assured can work with mocking frameworks:

WireMock: Create mock API responses
MockServer: Set up mock endpoints
Custom Filters: Intercept and modify requests/responses

How do you handle API environment management in Rest Assured?

Rest Assured can manage multiple environments using:

Property Files: Store environment-specific configs
Maven Profiles: Switch between environments
Environment Variables: Use dynamic configurations

How do you implement retry logic for flaky APIs?

Rest Assured can handle unreliable APIs using:

Custom Retry Mechanism: Implement exponential backoff
Error Handling: Define retry conditions

Example:

public Response executeWithRetry(RequestSpecification request, int maxRetries) {
                int retryCount = 0;
                while (retryCount < maxRetries) {
                    try {
                        Response response = request.get();
                        if (response.getStatusCode() == 200) return response;
                    } catch (Exception e) {
                        Thread.sleep(Math.pow(2, retryCount) * 1000);
                        retryCount++;
                    }
                }
            }

How do you handle GraphQL queries in Rest Assured?

Rest Assured can test GraphQL APIs by:

Query Building: Construct GraphQL queries
Variable Handling: Pass dynamic variables

Example:

String query = """
                {
                    "query": "query ($id: ID!) { user(id: $id) { name email } }",
                    "variables": { "id": "123" }
                }
            """;

            given()
                .contentType("application/json")
                .body(query)
            .when()
                .post("/graphql")
            .then()
                .body("data.user.name", equalTo("John"));

How do you handle WebSocket testing in Rest Assured?

Rest Assured can test WebSocket endpoints using:

WebSocket Client: Establish WebSocket connections
Message Handling: Send and receive WebSocket messages

Example:

WebSocketClient client = new WebSocketClient();
            client.connect("ws://api.example.com/ws");

            client.send("{ \"type\": \"subscribe\", \"channel\": \"updates\" }");
            String message = client.waitForMessage();
            assertThat(message).contains("subscribed");

How send dynamic query parameters?

We can send dynamic query parameters using the queryParams() method:

Map queryParams = new HashMap<>();
    queryParams.put("page", "1");
    queryParams.put("limit", "10");

    given()
        .queryParams(queryParams)
    .when()
        .get("/api/users")
    .then()
        .statusCode(200);