Interview #47: API - What is base URI, and how do you configure it in RestAssured?

The Base URI in the context of REST APIs is a foundational address that serves as the root for accessing all endpoints of an API. It represents the fixed portion of the API's URL structure, simplifying configuration and avoiding repetition in test scripts or API interactions. For example:

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• If the API's full URL for fetching a user's details is https://api.example.com/v1/users/123, the base URI would typically be https://api.example.com/v1.

By defining the Base URI separately, you can construct specific endpoint paths more concisely, e.g., /users/123.

Importance of Base URI in RestAssured

RestAssured is a popular Java library for testing RESTful web services. It provides a clean and efficient way to define API requests, including headers, query parameters, and payloads.

In RestAssured, setting the Base URI helps you avoid repeating the same base address in every test. For instance, if all endpoints for your API begin with https://api.example.com/v1, you only need to define it once. This improves maintainability and readability, especially in larger projects.

Configuring Base URI in RestAssured

RestAssured offers multiple ways to set the Base URI. Here are the most common methods:

1. Using the RestAssured.baseURI Static Field

You can configure the Base URI globally using the RestAssured.baseURI static field. Once set, it applies to all API requests unless overridden.

Example:

import io.restassured.RestAssured;

public class ApiTest {
    public static void main(String[] args) {
        // Set the Base URI
        RestAssured.baseURI = "https://api.example.com/v1";
        
        // Perform a GET request
        RestAssured
            .given()
            .when()
            .get("/users/123")
            .then()
            .statusCode(200);
    }
}        

Explanation:

• The baseURI is set to https://api.example.com/v1.
• The endpoint /users/123 is appended to the Base URI, forming the full URL https://api.example.com/v1/users/123.

2. Using RequestSpecification for Localized Configuration

If you need to use different Base URIs in the same test suite, you can create a RequestSpecification with its own Base URI.

Example:

import io.restassured.RestAssured;
import io.restassured.specification.RequestSpecification;

public class ApiTest {
    public static void main(String[] args) {
        // Create a RequestSpecification with a custom Base URI
        RequestSpecification spec = RestAssured.given().baseUri("https://api.example.com/v1");

        // Perform a GET request using the specification
        spec
            .when()
            .get("/users/123")
            .then()
            .statusCode(200);
    }
}        

Explanation:

• A RequestSpecification is configured with a specific Base URI.
• Only requests created using this specification will inherit the configured Base URI.

3. Using @BeforeClass or Configuration File for Base URI Setup

For better organization in test suites, you can set the Base URI in a @BeforeClass method or use external configuration files.

Example using @BeforeClass:

import io.restassured.RestAssured;
import org.testng.annotations.BeforeClass;
import org.testng.annotations.Test;

public class ApiTest {
    @BeforeClass
    public void setup() {
        // Set the Base URI before running the tests
        RestAssured.baseURI = "https://api.example.com/v1";
    }

    @Test
    public void testGetUser() {
        RestAssured
            .given()
            .when()
            .get("/users/123")
            .then()
            .statusCode(200);
    }
}        

Example using an external configuration file:

import io.restassured.RestAssured;
import java.util.Properties;
import java.io.FileInputStream;

public class ApiTest {
    public static void main(String[] args) throws Exception {
        // Load configuration from a properties file
        Properties props = new Properties();
        FileInputStream fis = new FileInputStream("config.properties");
        props.load(fis);

        // Set the Base URI from the properties file
        RestAssured.baseURI = props.getProperty("baseURI");

        // Perform a GET request
        RestAssured
            .given()
            .when()
            .get("/users/123")
            .then()
            .statusCode(200);
    }
}        

Configuration file example (config.properties):

baseURI=https://api.example.com/v1        

4. Chaining the baseUri Method

In situations where you prefer inline configurations, you can use the baseUri method directly within a request.

Example:

import io.restassured.RestAssured;

public class ApiTest {
    public static void main(String[] args) {
        // Perform a GET request with an inline Base URI
        RestAssured
            .given()
            .baseUri("https://api.example.com/v1")
            .when()
            .get("/users/123")
            .then()
            .statusCode(200);
    }
}        

Key Considerations

• Global vs Local Configuration: Use global configuration (RestAssured.baseURI) for consistency across tests. Use RequestSpecification or inline configurations for tests requiring different Base URIs.
• Environment-Specific URIs: When testing multiple environments (e.g., dev, staging, production), use external configuration files or environment variables to dynamically set the Base URI.

Conclusion

The Base URI in RestAssured is a foundational component for efficient and maintainable API testing. Whether set globally, locally, or dynamically, it simplifies the structure of test scripts, reduces redundancy, and makes transitioning between environments seamless. Choose the method that best fits your project's complexity and testing needs.