Recording

Loadcoder can generate performance tests from recorded user interactions in a web browser. This means that you can browse your way through the scenario you want to simulate in the performance test, and then instruct Loadcoder to generate Java code containing network calls corresponding to the ones made from the browser. Pretty cool, right?

The recording is actually not done by Loadcoder, but rather the browser some other program that manages the network calls, like a proxy for instance. Many browsers and proxies has the ability to log the network interaction that is taking place, and then save this log to .har file. This har file is then read be Loadcoder that interprets the content and then generates a load test.

Follow the below description of each step in how to perform the recording and generation

Record the har file

This section describes how to record a user web browser scenario and save to a har file

Choose browser

Even though the har file format is specified, it is up to the browser vendors how they are implemented. This means that the har file will look different depending on what browser you use, ultimately affecting your generated Load test. The browsers below have been evaluated and recommended in descending order

• Firefox (Recommended Browser)

  Pros:
  • Saves the response body, useful when expecting certain responses
  • Can Filter out in the network log which types of traffic to save
  Cons:
  • Bug around generation of cached responses (variable "expires" that should be a date, but gets parsed as value false in some cases. This makes the har file unparsable for Loadcoder. Just happens occasinally. Work around is simple to empty the network log and remake the recording.

• Chrome

  Pros:
  • No observed problems in generated har file. Always parsable
  Cons:
  • Doesnt save all response bodies
  • No filtering for what types of traffic to save to har

Perform the recording

• Open the browser
• Open the Network log by pressing key F5 and then choose the Network tab
• Clear the Network log if there are any entries logged
• Start browsing your scenario you want to performance test
• Once you completed the browsing, the Network log will be filled with network calls
• If applicable in the browser, you can filter out the entries that you dont want to keep. A rule of thumb is to keep everything except some static content like JavaScripts, images, other media and fonts.
• Right click in the Network log and choose to save it as a HAR file.

Generate the LoadTest

The generation of a Loadcoder test is done by creating and using an instance of the class LoadcoderGeneratorBuilder.

Follow the below example to create a generator. Consult the Javadoc for details around the arguments.

import static com.loadcoder.statics.Statics.SECOND;
import java.util.Arrays;
import com.loadcoder.cluster.clients.influxdb.InfluxDBClient;
import com.loadcoder.network.LoadcoderGeneratorBuilder;

public class LoadcoderGenerator {

  public static void main(String[] args) {

      new LoadcoderGeneratorBuilder(
          "/path/to/recording.har",
          Arrays.asList("https://www.website.com", "https://another-site-to-loadtest.com"),
          "javapackage.for.generated.code", 
          "src/test/java/javapackage/for/generated/code", 
          "src/test/resources/generated-resources" 
          )
          .load(120 * SECOND, 3, 5)
          .sendResultTo(InfluxDBClient.influxReporter("WebSiteTests", "ShortLoadTest"))
          .checkResponseBodiesContaining(Arrays.asList("shoppingcart"))
          .generate();
      
  }
}

Finishing touches

The generated test should not be taken as finished, ready to execute load test. The generated code will be running, but in order to have it exactly as you like, you will need to go through the generated code and make it complete

Below is a list of things to migth want to adjust. You find the Java classes in the directory you specified in the generator

ScenarioLogic

• Correct transactions

  Go through the list of transactions the verify that the correct transactions are there. Loadcoder has its own logic to select the transactions that you probably want to include based from the request URL. Remove transactions that you don't want. If you miss certain transaction you can simply copy another transaction and adjust it into how it should look like.

• Transaction names

  Loadcoder generates transaction names by trying to figure out the most essential parts of the URL, making some of them quite cryptic. It is a good idea to rename them to something more describing.

• Parameter dependencies

  In some cases there can be dependencies between HTTP calls. For instance, some value in a HTTP reponse may be needed in the next HTTP request. Loadcoder have no support for generating this logic, so you have to manually fix this.

GeneratedLoadTest

• Load definition

  Even though an initial load level is created by the generator, additional adjustments may be needed. Modify the use of the LoadBuilder instance so that is meet your requirements of your load test.

Other

• Test data

  In many cases you need to use some kind of test data for your load test. Consult the Loadcoder Core Documentation in how to manage test data in a best practise.