API Tests Lab

This lab exists as a Git submodule for this web app repository because the test scripts in this lab require the web application to be running. Instead of cloning this repository directly, you can just clone the web app repository and navigate to the tests/rest_api directory. The below documentation serves to outline the API functions that will be tested, as well as the process for testing API's.

1. Introduction

This lab repository contains scripts and documentation for testing a web application's REST API. It contains scripts for testing the API with the built-in Python requests library, as well as instructions for testing with the Postman GUI application.

WARNING: The scripts included in this repository are NOT Pytest scripts. This lab is about testing an API as a whole from outside of the program code, hence the use of the requests library and the Postman application to send requests to the running application externally. Follow the directions below to run the scripts properly.

2. Running the test scripts

IMPORTANT NOTES:

• The tests depend on the Python requests library which is installed in the virtual environment. You will need to activate the virtual environment before running both the tests and the application.
• The web app needs to be actively running when the test scripts are executed. You will most likely need to open another terminal window to run both at once. Make sure you activate the virtual environment in both terminals.
• The database for the application uses a unique primary key for the item ID's and it uses a counter to generate new ID's. However, when testing the POST method of the API, it will increment the ID counter without adding a new entry to the database (as it deletes the test entry once finished to clean up after the test). This will create gaps between ID values. For this reason, it might be important to run the flask --app clothing_store init-db command once concluded with testing to make sure the database is reset back to default.

Instructions

1. Follow the instructions listed here to create a virtual environment, install the dependencies, and run it.

2. You can then run any individual tests you want with the command python <file name>.py. If you want to run all of them at once, run the test_all.py file with python test_all.py.

How do they work?

Feel free to open the files in your text editor to check the code used to test the API. They all feature comments that explain and describe each step of the process and what is being tested at each point.

3. Testing Philosophy

What is being tested?

The web application supports the following 5 API calls that need to be tested:

• GET at /api/products to retrieve a list of all products currently in the database.
• GET at /api/products/<id> to retrieve the information about a specific product in the database with the specified ID.
• POST at /api/products to add a new product to the database.
• PUT at /api/products/<id> to change the values of the product with the specified ID.
• DELETE at /api/products/<id> to remove a product with a specified ID from the database.

Testing Strategy

For this lab, there are both provided Python scripts to test the API, as well as instructions for testing the API manually using the Postman application. The testing strategy of the scripts is to make a request, supply necessary data if necessary, and then test the response against multiple conditions. In the case of testing things like POST or PUT requests, the API's response to the request contains the data as it appears in the database (if the request was successful), so there is no need to follow up those requests with GET requests to make sure the changes "went through" successfully.

Postman Tutorial

This will go over the basic usage of Postman when testing Web APIs and RESTful services. To dive deeper into Postman see their official documentation.

Prerequisites

Before starting the tutorial, go to our Sample Web Application and clone it. Then follow the instructions in the README to start the local web server. We will be testing this applications API throughout this tutorial.

If you'd like to know more about the Sample Web Applications API, you can find the documentation in the API Overview.

1. Install Postman

Install Postman from their downloads page

2. Send your first request

The easiest type of request to start with is a GET request as it will only retrieve information.

If you haven't already, go clone the Sample Web Application and start the local web server before continuing.

For the requests we will use the following URL:

http://localhost:5000/api/products

To send the request do the following:

1. Set the HTTP request method to GET
2. Paste the above API URL in the request URL input
3. Click the send button
4. Verify the API responded with the 200 OK status code
5. Verify the API responded with a JSON object containing a list of all the products

3. Send a POST request

POST requests are used to send data to the server in the body of the request and are typically used to create a new resource. In this case, we will be creating a new product in the database.

First create a new tab in Postman for the new request.

Next, in the new tab you created:

1. Set the HTTP request method to POST
2. Paste the same URL for the last request in the request URL input (http://localhost:5000/api/products)
3. Click on the Body section of the request (under the URL input)
4. Click the raw option
5. Select JSON from the dropdown menu

Next paste in the JSON data for the new product in the body text area

{
	"product": {
		"name": "Running Shoes",
		"price": 49.99,
		"description": "Comfortable running shoes.",
		"quantity": 10,
		"category_id": 3
	}
}

Finally, send the request and verify the product was created:

1. Click the send button
2. Verify the HTTP response status code is 201 Created
3. Verify the created product was returned in the response

To learn more on your own, go to the API Documentation and try to update the product you created with a PUT request. Then delete the product with a DELETE request.