Postman is a well-known API development tool that’s utilized by developers all over the world. It offers an intuitive interface for creating, testing, and documenting APIs. One of Postman’s most significant advantages is its capacity to create tests, which are automated scripts that can be employed to verify API responses. In this article, we’ll look at some of the ideal Postman tips and tricks for creating compelling tests.
Use Environment Variables
Environment variables are an extremely good method for controlling and recycling values throughout multiple Postman requests. You can create environment variables and link them in your requests instead of hardcoding values such as API keys or URLs in every request.
To add an environment variable, go to the Postman app’s top right corner and choose “Manage Environments.” You then have the option to create a new environment or choose an existing one. You can start creating variables after you’ve created or chosen an environment by clicking the “Add” button and entering a key-value pair.
To reference an environment variable in a request, enclose the variable name in double curly braces (e.g. {{variable_name}}).
Example
const apiKey = pm.environment.get("api_key");
pm.sendRequest({
url: `https://api.example.com?key=${apiKey}`,
method: 'GET'
}, function (err, res) {
// handle response
});
Organizing Test Suites
It is critical to keep tests organized and controllable when writing them. Postman allows you to categorize tests into test suites. Test suites help you in arranging your tests around a common theme. You could, for instance, create a test suite for all of your verification tests or a test suite for all of your API endpoints.
To create a test suite, select “Test Suite” from the “New” menu. You can then name and characterize your test suite. You can drag and drop tests into your test suite after you’ve created them.
Use Pre-Request Scripts
Before a request is sent to the server, pre-request scripts run. They may be utilized to define variables, custom tailor request headers, or accomplish any other tasks before sending the request. Pre-request scripts can be incredibly helpful when testing APIs that demand authentication. A pre-request script, for instance, may be utilized to define an authorization header with a token from an original request.
Here is an example of a pre-request script that sets an authorization header:
const token = pm.globals.get('auth_token');
pm.request.headers.add({
key: 'Authorization',
value: 'Bearer ' + token
});
Use Assertions
Assertions are employed to validate an API response. Postman contains an array of assertions that may be employed to validate the status code, response body, response headers, and other variables. When testing APIs, assertions can be very beneficial because they assist in making sure that the API returns the anticipated outcomes.
Here is an example of how to use assertions to verify the status code of a response:
pm.test("Status code is 200", function () {
pm.response.to.have.status(200);
});
Use Chaining Requests
Request chaining is a method for accomplishing numerous requests in a single test script. When testing APIs that demand numerous requests to finish an assignment, chaining requests can be beneficial. When testing an API that creates a new user, for instance, you may have to initially verify the user’s identity before creating the user.
Here is an example of how to chain requests in Postman:
pm.sendRequest('GET', 'https://api.example.com/authenticate', function (response) {
const token = response.json().token;
pm.send
Test Response Status Codes
API testing includes the evaluation of response status codes. Using the pm.test() function, Postman makes it simple to test status codes.
pm.test("Status code is 200", function () {
pm.response.to.have.status(200);
});
In this example, the pm.test() function is used to check that the response status code is 200. If the status code is not 200, the test will fail.
Creating Mock Servers
You can use Postman to create mock servers for your API endpoints. Mock servers replicate your API endpoints and return predetermined responses. This attribute is particularly helpful when testing your API against a broad variety of inputs or simulating various situations. Simply tap the “Mock Servers” button and enter your endpoint to generate a mock server. Then, from the “Servers” menu, you can just use your mock server in your API requests.
Using Newman for CI/CD Integration
Newman is a command-line tool that lets you execute Postman collections from a continuous deployment delivery environment. This function is particularly helpful when it comes to automating your API integration and testing processes. Install Newman on your CI/CD environment and make use of the command-line interface to run your Postman collection. Newman will then operate your collection and produce an overview, so you can spot any errors or concerns as soon as possible.
Generating API Documentation
You can use Postman to generate documentation for your API endpoints. Both developers and users benefit from documentation because it provides a clear and concise description of your API endpoints and their functionality. Simply click the “Documentation” button and enter your endpoint to generate documentation. Postman will then generate documentation for your endpoint, which will include the URL, input parameters, response format, and any other pertinent information.
Using Keyboard Shortcuts
Postman comes with plenty of keyboard shortcuts to assist you in saving time and streamlining your workflow. Among the most beneficial shortcuts are:
- Ctrl + N: Create a new request
- Ctrl + Enter: Send the request
- Ctrl + E: Edit the request
- Ctrl + Shift + E: Edit the request in a new tab
- Ctrl + /: Comment/uncomment the current line
A complete list of Postman keyboard shortcuts can be obtained by tapping the “Keyboard Shortcuts” button in the application’s bottom-right corner.
