Tutorial 10 – API Testing in Cypress
What you will Learn :
What is API?
API Testing in cypress using cy.request() command (GET method)
API Testing in cypress using cy.request() command (POST method)
What is API (Application Programming Interface)
Look at below figure. When you download some application (example Zoho app, on your mobile or desktop) and when you try to signup, it might ask you if you want to Login with your Gmail/Facebook/Twitter credentials. So when you login using any of these apps, you are successfully logged in. Here, Zoho and Facebook/Gmail are different applications, but they communicate eahc other using APIs. So facebook app exposed some of it’s APIs to provide facility to login Zoho.
So API is nothing but a resource through which you are getting information from any database, but you don’t have the direct access to the db. Now makemytrip does not have access to the database of airlines (Indigo etc). Instead, airlines expose some of their APIs. So makemytrip is getting the information from spicejet or Air India through an API. So if a user enters source/destination/date & searches a flight on makemytrip.com, the latter in turn makes an API call to all the airlines and display the results in the browser. 
API Testing in cypress using cy.request command (GET)
We will be using http://dummy.restapiexample.com/ to test an API using cypress. Let us first see the GET method
If you click the url (shown under Full route), you would see all the employee data
Click the Details link
You would see a sample of how the result will be dispayed when we request this api
Lets create a new spec.js file
cy.request() command accepts 2 arguments: the first one is type of HTTP method (here GET), the second is the request url
Save the file & run, you see below
Press F12 and go to Console
Click the request link from left hand side and expand Yielded
Expand body and expand data. You would see the data of all the 24 employee. You can also see Array(24)
Let us try to assert the status code
Save the file
Click 
seen on LHS.
On the RHS, you would see ‘Actual’ is same as ‘Expected’
Now from the previous snapshot we know that the response body data has length of 24
Let us validate this as well (see line 7 below)
Save the file. Notice that Actual is same as Expected, see below
API Testing in cypress using cy.request() command (POST method)
Let us now see how to automate a POST method using cypress. The POST method will create a new record in database. Let us use another dummy website https://reqres.in/
Click POST, you would see a sample Response
Let us comment the current ‘it’ method & add a new ‘it’ method. In the POST method, we have to pass the sample json (for the new record) as 3rd argument to the cy.request()
Save the code, notice below that the test is apss & new record is inserted
Now let us add another user and validate the ‘name’ field in the body
Save.
Notice that assertion gets passed
So this is how we can test basic APIs using cypress.
Thanks for reading!