Automating API tests with REST Assured

What is an API?

• Application
• Programming
• Interface

The API Contract

• Request
  . Endpoint
  . Headers
  . Body
  
• Response
  . Status Code
  . Headers
  . Body
  

REST Assured Feature

• Parameterization and data driven testing
• Verifying response headers and bodies
• Optimizing your test code through reuse
• (De-) serializing request and response bodies
• Java DSL for writing tests for RESTful APIs
• Runs on top of JUnit or TestNG
• Supports all HTTP methods (GET, POST, PUT, DELETE, ...)
• Supports Gherkin syntax (Given/When/Then)
• Uses Hamcres matchers for checks
• Uses JsonPath/Gpath and XmlPath for selecting elements from response
• Developed and maintained by Johan Haleby
• Source: https://rest-assured.io/

Configuring REST Assured

• Maven

        <!-- https://mvnrepository.com/artifact/io.rest-assured/rest-assured -->
        <dependency>
            <groupId>io.rest-assured</groupId>
            <artifactId>rest-assured</artifactId>
            <version>4.4.0</version>
            <scope>test</scope>
        </dependency>

• TestNG

        <!-- https://mvnrepository.com/artifact/org.testng/testng -->
        <dependency>
            <groupId>org.testng</groupId>
            <artifactId>testng</artifactId>
            <version>7.4.0</version>
            <scope>test</scope>
        </dependency>

API Test

Website: https://www.zippopotam.us/

• Supplies location data related to given country and zip code

• An example request and response
  Structure: api.zippopotam.us/country/postal-code

api.zippopotam.us/us/90210

• JSON Result

{
   "post code": "90210",
   "country": "United States",
   "country abbreviation": "US",
   "places": [
       {
           "place name": "Beverly Hills",
           "longitude": "-118.4065",
           "state": "California",
           "state abbreviation": "CA",
           "latitude": "34.0901"
       }
   ]
}

Tests Result

How to create a parameterized REST Assured test?

• Step 1: Create a test data collection
• Step 2: Feed data collection to your test method
• Step 3: Use path parameters to parameterize REST Assured tests
• Step 4: Update the specified test data

Optimizing REST Assured code

1- Reusable request specifications
2- Reusable response checks
3- Extracting response values for reuse