Raluca's Quality Assurance and Software Testing: Postman - Extracting login token and using it in requests

Introduction

Postman is a powerful GUI platform to make your API development faster & easier, from building API requests through testing, documentation and sharing. In this article we'll show you how to:

- take the token from your login post and use it later for authorization in later requests
- define environment variables and use them in requests
- test your API by testing response code, response time, response body content, etc.
As example, we are going to test this workflow:
- login to https://www.pincello.com
- create a new timeline

* Pincello is a beta web application that allows you to make professional timelines quickly that is the Web version of a PowerPoint addin (for more details visit https://www.officetimeline.com/).

Extract token data from login
Postman gives the possibility to extract values from the response and saving it inside an environment or a global variable. Environment and global variables let you keep track of everything that affects API state. Some examples of common variables you would use with an API are session tokens, user IDs, file IDs.

What are the steps for taking the token from login:

1. Launch Postman Chrome Extension

2. Create a new collection (from the top left part)

3. Name it, for example Pincello Testing

4. Open Manage Environments (from the top right part)

5. Add a new environment, e.g. Pincello and add a new key, e.g. token. Leave the value empty.

6. Set this environment (Pincello) to the current collection (Pincello Testing)

6. Post login data and extract via Test tab the access_token and then place it in the environment variable.

In this case we need to create a new request with

- url = {{url}}/token, where {{url}} is another environemnt variable that represents your url that you want to test

- type POST

- body, in this case of type x-www-form-urlencoded with some inputs, those values are stored also as environment variable

*every call to an environment variable is made by using environment key value with {{}}

- you then need to go to Test tab and place the result of post response in token environment variable. To do this, white this javascript code in your Test tab

7. Write tests for login request, e.g. response time, response status code = 200. To do this add tests to your Test tab from Code list

8. Every request after login, will require an authorization, thus, we should add Authorization header for the next requests like in the image below, by using the token previously extracted.