SuperTest - A Detailed Guide To Efficient API Tests

SuperTest is not some fictional thing and it has a huge role in the smooth performance of your application. So, let’s find out more about it with some factual discussion.

In this digital era, you can hardly spend a few moments without technology or more specifically software applications. And, to serve the endless needs of people, numerous applications are being built every moment, but do you completely understand how those applications work?

If you are one of the regular readers of our blogs, you must already know that APIs are something that builds the connection between two different applications or sometimes even between two different modules of the same software to let the applications complete their tasks.

So, you may have already gone through our detailed articles on API testing, and you know why it is so important and how it is done. That’s where SuperTest performs some crucial roles, and we will go into its depths in this article.

What Is SuperTest?

SuperTest is a Node.js library that is used for API testing. While it is normally used by testers and developers for writing automated tests for routes and endpoints, it also extends another library called superagent which is a JavaScript client for Node.js and the browser.

SuperTest is used by developers as a standalone library or with popular JavaScript testing frameworks like Mocha and Jest.

Why Should You Use SuperTest?

SuperTest is not casually called one of the finest API testing solutions. The following benefits of using it stand by the fact -

  • SuperTest provides a high-level abstraction to test HTTP requests. That means if your Node.js application is running an HTTP server, you don’t need a running server.
  • It allows you to make requests directly.
  • It can easily integrate with other testing frameworks without any additional tools.
  • To test any HTTP requests, it just requires a few lines of command by sending a method like GET, PUT and POST.

How Can You Start Using SuperTest?

Installing and using SuperTest is a pretty simple step-by-step process that we have jotted down below.

Step 1: Installing the SuperTest Package

  • First, install the project’s dev dependencies. For example, if you are adding TypeScript, install the type definitions.
  • After the package is installed, set up the test command in the package file.
  • Now, it’s time to install the testing framework. It is so advantageous to write automated tests using this framework that it will help you determine if any part of the application has gone wrong.

Step 2: Creating An HTTP Request

There are two ways of creating an HTTP request so, let’s explore them both so that you can select the suitable one for you.

  • This method needs you to follow a few small steps that are -
  • It tests an external API or an internal API already deployed and running in the staging environment. So, for that, you need to provide the URL as a parameter, and use the GET() method.
  • The previous step will tell the Supertest to use the HTTP GET verb. You can also include additional methods in the call to set authentication. It allows you to add custom HTTP headers and body too.
  • Finally, use the END() method to finalize the request and call the API server.
  • Now comes the second method which is only useful if you have built the API with a Node.js framework. In this method, if necessary, the SuperTest starts a test server and sends the requests there.

Step 3: Setting Response Expectations

  • First, set the expectations for a functional API test. The way to do it is by confirming that the API responds as expected.
  • Extend the superagent using the expect() method so that you become able to test several things related to the API response.

The HTTP APIs respond with different status codes to show different results as the following -

  • Returning a status code in the 4xx range means an error.
  • Returning a status code in the 5xx range signifies server errors.
  • Returning a status code in the 200 to 204 range indicates a successful API request.

Step 4: Checking The Response Bodies

  • Checking the response bodies is a super-important task. Checking for just the HTTP status codes and headers can eventually result in shallow testing or smoke testing. That way you can check whether the API is responding correctly, but it will not help you in thorough testing of specific properties.
    To properly check the information about the output and the success or failure message, you must also check for response bodies.
  • Now, there are multiple ways of checking the response bodies. Two popular methods out of them are -
  • If an API returns a message and status property, check if they exist or if the expected properties are present in the JSON object.
  • Another way of checking the response bodies built into SuperTest is by passing a string or regular expression to the expect() method. For the actual testing part, the string should match the whole body, and the regular expression would review parts of it.

How To Combine SuperTest and Mocha?

You must have heard about the popular JavaScript testing framework Mocha, and as we previously mentioned, you can easily integrate SuperTest with it. If you have previously used Mocha, you are surely familiar with its methods. So, let’s see how you can use those methods for this integration.

The mocha methods describe() and it() can help you structure your tests. There are just a few basic differences between the Mocha integration and traditional methods for using SuperTest. For your ease, we have jotted down a sample code below.

describe('Random Dog Image', function() {
  it('responds with expected JSON structure', function(done) {
      .expect('Content-Type', 'application/json')
      .expect(/{"message":".*","status":"success"}/, done);

Source of code:,frameworks%20like%20Mocha%20or%20Jest.

How To Design A SuperTest?

Designing a SuperTest is quite easy. You can simply follow these steps -

  • In the case of internal APIs, you should test all the exposed endpoints. For that, you can either write a unit test for one endpoint or can use multiple API calls to test the workflows involving numerous API calls.
  • In the case of external APIs, it is a good idea to test the reliability of all the endpoints that are being consumed.


SuperTest is a very helpful solution for all your API testing needs. This article tells you a lot about what it is, why you should use it, and how you can proceed with using it. So, we recommend you minutely go through this detailed guide about installing, setting up, and using SuperTest.

However, there is much more to learn about this amazing library that will also surely get a lot of updates in the future. But, you don’t need to worry about staying up to date with the necessary information as we will definitely keep publishing more amazing articles on this topic as well as several important tech topics.

Also, you know it goes without saying that this digital era is all about speed, perfection, and efficiency. And, in the tech field, those can only be achieved by automating as many things as possible. Having said that, we must remind you how important it is to automate the large, complicated test suites in your business.

The point is that automating test suites is a matter of a few seconds and a few clicks on the amazing dashboard of Preflight. This simple yet supremely powerful browser extension enables anyone to create, run, and manage complex test cases within a few seconds regardless of his/her coding knowledge. To start experiencing it, you just need to sign up with us.

To know more about our products, feel free to reach out to us anytime. Our website is always there for you to keep you abreast of the latest developments in our products and services. Also, if you are a keen reader of tech articles, our blog page is a place that you will surely love to check out.