Performance Testing with Gatling

In this guide, we will cover how to perform a performance test on the Swagger Petstore API using Gatling. Gatling is a user-friendly, Java-Scala based load testing tool that allows you to characterize user behavior and simulate thousands of concurrent users accessing your application.

To start using Gatling, you need to set up a suitable development environment.Let’s set the pom.xml

Using Maven:

 <dependencies>
    <dependency>
      <groupId>io.gatling.highcharts</groupId>
      <artifactId>gatling-charts-highcharts</artifactId>
      <version>${gatling.version}</version>
      <scope>test</scope>
    </dependency>
  </dependencies>

2. Creating a Test Scenario

A performance test scenario defines the actions to be tested and how they will be executed. Below is an example of a test scenario for five different endpoints of the Swagger Petstore API(https://petstore.swagger.io/):

import static io.gatling.javaapi.core.CoreDsl.*;
import static io.gatling.javaapi.http.HttpDsl.*;
import io.gatling.javaapi.core.*;
import io.gatling.javaapi.http.*;
public class SwaggerSimulation extends Simulation {
    FeederBuilder<String> feeder = csv("pet_ids.csv").random();
    ChainBuilder getPetById = 
        feed(feeder)
        .exec(
            http("Get Pet by ID")
                .get("/pet/#{petId}")
                .check(status().is(200))
        )
        .pause(1);
    ChainBuilder findPetsByStatus = 
        exec(
            http("Find Pets by Status")
                .get("/pet/findByStatus?status=available")
                .check(status().is(200))
        )
        .pause(1);
    ChainBuilder addPet = 
        exec(
            http("Add New Pet")
                .post("/pet")
                .body(RawFileBody("addPet.json")).asJson()
                .check(status().is(200))
        )
        .pause(1);
    ChainBuilder updatePet = 
        exec(
            http("Update Pet")
                .put("/pet")
                .body(RawFileBody("updatePet.json")).asJson()
                .check(status().is(200))
        )
        .pause(1);
    ChainBuilder deletePet = 
        exec(
            http("Delete Pet")
                .delete("/pet/#{petId}")
                .check(status().is(200))
        )
        .pause(1);
    HttpProtocolBuilder httpProtocol = http
        .baseUrl("https://petstore.swagger.io/v2")
        .acceptHeader("application/json")
        .userAgentHeader("Mozilla/5.0 (Windows NT 10.0; Win64; x64)");
    ScenarioBuilder scn = scenario("Swagger API Test")
        .exec(getPetById, findPetsByStatus, addPet, updatePet, deletePet);
    {
        setUp(
            scn.injectOpen(rampUsers(10).during(10))
        ).protocols(httpProtocol);
    }
}

3. Preparing Test Data

In Gatling tests, the data used in scenarios can be stored in CSV files or JSON format. For example, the pet_ids.csv file could contain the IDs of pets to be used during the test.

4. Running the Test

To run your Gatling tests, you can use the following command:

mvn gatling:test

This command runs the Gatling test using Maven and stores the results in the target/gatling directory.

5. Analyzing Test Results

After the tests are completed, Gatling generates a detailed HTML report. This report provides insights into the performance of the endpoints tested and includes:

• Response Time Distribution: Shows the average, minimum, and maximum response times for requests.
• Request Failure Rates: Displays the percentage of failed requests during the test.
• Average Response Time Per User: Indicates the average response time for each user.

6. Advanced Usage and Optimization

To create more complex scenarios, you can leverage Gatling’s advanced features:

• Dynamic Data Usage: Use data that varies between users to create more realistic test scenarios.
• Conditional Requests and Loops: Ensure that requests are made under specific conditions or are repeated a certain number of times.

Github Link: https://github.com/dogangunemre/GatlingPerformanceTesting

Thanks!