Now that you know a little about API documentation, you should learn more about it, figure out its pros and cons, get to know Swagger and Swagger files, and understand why it's important to a tester.
API documentation for testing
It is a valuable resource for testers. It shows detailed information about how different parts of a website work together and allows for thorough testing. Let's look at the advantages and disadvantages of using APIs in testing.
Pros:
Clear functionality understanding. API documentation acts as a guide for testers, helping them understand what an API does.
Improved test coverage. API documentation helps testers get complete test coverage. It gives details about the parameters, expected responses, and error codes. This helps testers design tests that cover many scenarios.
Time and effort saving. API documentation can save testers time and effort by giving code examples. These help testers quickly understand how to make API requests and interpret responses.
Cons:
Incomplete or outdated information. API documentation can sometimes be incomplete or not up-to-date. This may cause wrong ideas about how the API works.
Lack of explanatory context. Sometimes API documentation doesn't give enough background. Testers might find it hard to make good test cases or find potential issues without this information.
Limited troubleshooting guidance. When testers run into problems during API testing, they often look to the documentation for help. But some API documentation might not give detailed problem-solving steps or error scenarios.
With API documentation, testers can easily find out the inputs and expected outputs for each API endpoint. An endpoint is a specific URL or URI that is the entrance for talking with a web service. It lets clients use or change resources.
Testers can also see how different APIs depend on each other. This makes test design easier. Testers can concentrate on making test scenarios that check if APIs are working right and how they talk to each other. Having API documentation in the testing process helps spot problems early. Testers can see where the documentation and the actual API don't match. This lets them solve these issues quickly and avoid bigger problems later.
Approaches of API docs organisation
There are many ways to organise API documentation. What you choose often depends on the API, who will use it, and what the developer prefers. Here are some common methods:
Categorise endpoints. Start by putting API endpoints into categories. For a restaurant's website, you might have groups like "Menu Endpoints," "Reservation Endpoints," and "User Management Endpoints." This helps you find specific endpoints fast based on what they do.
You would test the API endpoint /menu to make sure it gives the right menu list. The methods for this could be GET (to get the menu) and POST (to add a new menu item).Group by functionality. Within each category, group endpoints by what they do. For example, under "Menu Endpoints," you could have groups like "Get Menu Items," "Search Menu Items," and "Add Menu Items."
When testing the reservation part of the restaurant website, the related APIs could be /reservations, /availability, and /booking. By putting these together, testers can easily understand how reservations work and test this functionality completely.Provide clear descriptions. Every endpoint should have a simple description saying what it does. For instance, if there's an endpoint for getting menu items, describe it like "Get a list of all menu items." This helps testers know what the endpoint is for.
The /menu endpoint's documentation should explain what parameters you can use (like page number, item category). It should also give examples of good requests and what responses to expect.Include request and response examples. It's important to show examples of how to make requests and what the responses will look like. This helps testers understand what parameters they need, what formats to expect, and what errors might look like. For instance, you can show how to ask for a menu item and what details you'd get back.
Document error handling. Remember to write about possible errors and what they mean. This helps testers expect and manage different error situations well. For example, if trying to add a menu item fails, the documentation should explain what errors might happen and what to do about them.
Open API format
Open API format is about an API that is open and documented, so anyone can use it and make apps that talk to the website. OpenAPI often uses YAML or JSON. Both are easy to read for people and machines. So, sharing information is easy. OpenAPI has become well-liked for making starting codes for apps.
One big plus of OpenAPI is that it is a central place for all API details. This makes it easier to make sure APIs follow the right styles and rules. API engineers and developers can use this to automatically make important API stuff like SDKs, code libraries, and documentation.
For example, if a restaurant wants a website and a smooth experience for customers, OpenAPI helps make SDKs for the menu, ordering system, and payment gateway. The code libraries made by OpenAPI give developers the tools to quickly make and change the website.
Also, OpenAPI has features to check API requests and find security problems early in development. This is key to making sure the website is safe from bad stuff. By using OpenAPI's checks and security measures, the website can be tested well and kept safe.
However, OpenAPI can be tricky to use fully without the right skills. Setting it up can be hard for new people. If the API details are not set right, it can cause mistakes and wrong code. If OpenAPI's details for menu items are not correct, it could show wrong data on the website.
Open API format lets you test scenarios like in real life. For example, you can make automated tests that work with the API and act like users. This way, you can check how the website answers to different things and make sure it's stable and works well. Plus, Open API lets you test how the website works with other apps. Like if users can book on the restaurant website through another app.
Here is a JSON code example for asking the restaurant website for something with OpenAPI:
{
"method": "POST",
"url": "https://api.restaurant-website.com/v1/menu/items",
"headers": {
"Content-Type": "application/json",
"Authorisation": "Bearer YOUR_ACCESS_TOKEN"
},
"body": {
"name": "Spaghetti Bolognese",
"description": "Classic Italian dish with meat sauce",
"price": 12.99,
"ingredients": [
"Spaghetti",
"Ground beef",
"Tomato sauce",
"Onions",
"Garlic",
"Parmesan cheese"
],
"calories": 650
}
}In this example, there is a POST request to the /v1/menu/items endpoint on the restaurant website's API. The request comes with a header set to application/json and an Authorisation header with an access token. The request's body has the data about a menu item, like "Spaghetti Bolognese", including the name, description, price, ingredients, and calories.
Swagger overview
Swagger is an open-source tool that helps developers and testers work with RESTful APIs. It gives different tools and rules that make using APIs easier. One part of Swagger is the Swagger UI, which makes interactive documentation from Swagger-compatible APIs. This makes it easy to get to know and understand API features.
With Swagger, making API documentation is easy. The restaurant's API documentation will include different parts, like:
Endpoints. The documentation will list all API endpoints, like "/menu", "/order", and "/reservation". Each endpoint will have a description, a request method (like GET or POST), and needed parameters (if any).
Authentication. If the API needs a login, the documentation will say how it works, like with API keys or OAuth.
Request example. The documentation will give example requests for each endpoint, including headers, body, and query parameters. Testers can use these examples to understand how to make their API requests during testing.
Response format. The documentation will show what the response should look like for successful requests, including headers and body. It might also talk about error responses for when requests don't work.
Error handling. The documentation will talk about different error situations and what error codes or messages the API might give back. This helps testers understand and manage errors well.
Using Swagger files in API testing tools
Swagger files, also known as OpenAPI Specification files, define and explain RESTful APIs. The OpenAPI Specification can be in both JSON and YAML formats. There's a certain order for testing the API.
Make a Swagger file. This file will guide you through testing. You can use any text editor or online Swagger editors to make the file. In it, you'll define endpoints, request and response formats, and any other needed details.
Choose an API testing tool. There are many tools, but let's say you pick Postman for its simplicity. It's a popular tool that lets you send API requests and check the responses.
Open Postman and add your Swagger file. Postman can import Swagger files easily. After importing, you will see all the API endpoints in Postman, with their request formats.
Start testing. Click on an API endpoint from the list. Postman will fill in the request format from the Swagger file. Add any needed parameters or headers, and press the send button.
Look at the response. Postman will show the API's response. Check if the response is right, has the correct data, and meets the Swagger file's requirements.
Do Steps 4 and 5 for each endpoint in the Swagger file. Test everything well, including special cases, to make sure the API is solid.
Using Swagger files in API testing saves time because all needed information is right there. No need to make requests by hand or look through long documents.
Conclusion
API documentation has details about formats, endpoints, parameters, etc. It gives you the guidelines you need to make effective test cases. Knowing how APIs work is key to making sure the software is reliable and functions well.