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HAR

The HAR (HTTP Archive) file format is a JSON-structured file that contains detailed network traffic data about a browser's interactions with the server serving content for a webpage. This archived log can be used by a web browser to export comprehensive performance data regarding the web pages it loads.

Prepare the HAR File​

Below are the essential steps to follow for recording HAR in Chrome (you can watch this video):

  • Launch a new tab in Chrome.
  • Open Chrome Developer Tools by pressing F12.
  • Choose the Network tab.
  • Ensure that the recording button (the round button) is active and displayed in red.
  • To record multiple consecutive page loads, check the Preserve log box.
  • Type in the URL of your site and begin performing the actions you want your simulated load-test users to carry out.
  • When you're done, click the "Export HAR" button to save your session's content.

Run Converter​

Use nb-converter command to parse HAR file and convert to NBomber Scenario:

nb-converter HarExample.har -t har -o HarHelloWorldScenario.cs

Edit the auto-generated Scenario​

In the previous step, the converter created a NBomber scenario for testing. Now, you should evaluate whether you have to change any part of the NBomber scenario. Depending on your use case, you might need to:

  • Edit steps.
  • Add reporting sinks.
  • Configure the load simulation.

For example: configuration for KeepConstant, where we control the number of concurrent users.

Scenario.Create("scenario", async context =>
{
    var step1 = await Step.Run("POST reqres.in/api/users (1)", context, async () =>
    {
        var request = Http.CreateRequest("POST", "https://reqres.in/api/users")
            .WithHeader("accept", "*/*")
            .WithHeader("accept-encoding", "gzip, deflate, br, zstd")
            .WithHeader("accept-language", "en-US,en;q=0.9")
            .WithHeader("cache-control", "no-cache")
            .WithHeader("content-length", "34")
            .WithHeader("content-type", "application/json")
            .WithHeader("origin", "https://reqres.in")
            .WithHeader("pragma", "no-cache")
            .WithHeader("priority", "u=1, i")
            .WithHeader("referer", "https://reqres.in/")
            .WithHeader("sec-ch-ua", "\"Opera\";v=\"116\", \"Chromium\";v=\"131\", \"Not_A Brand\";v=\"24\"")
            .WithHeader("sec-ch-ua-mobile", "?0")
            .WithHeader("sec-ch-ua-platform", "\"Windows\"")
            .WithHeader("sec-fetch-dest", "empty")
            .WithHeader("sec-fetch-mode", "cors")
            .WithHeader("sec-fetch-site", "same-origin")
            .WithHeader("user-agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36 OPR/116.0.0.0");

        request.WithBody(new StringContent(@"{\"name\":\"morpheus\",\"job\":\";leader\"}", Encoding.UTF8, "application/json"));

        var response = await Http.Send(httpClient, request);

        return response;
    });
})
.WithLoadSimulations(    
    Simulation.RampingConstant(copies: 50, during: TimeSpan.FromSeconds(30)), // ramping up to 50   
    Simulation.KeepConstant(copies: 50, during: TimeSpan.FromSeconds(30))     // keep 50
    Simulation.RampingConstant(copies: 0, during: TimeSpan.FromSeconds(30))   // ramping down to 0
);