Testing APIs with Postman

Learning Goals

• Review how to use Postman.

Review Using Postman

In the previous module, we learned how to use a tool called Postman as an API client when testing our servlets. We can use the same tool here too to test our Spring web applications!

So far, we've only created a controller class with GET requests, so we can easily test these in a browser's URL bar. But when we start introducing some other HTTP verbs, like POST, PATCH, and DELETE, it will be easier to use an API client, like Postman.

Even though we haven't introduced these other HTTP verbs yet in our controller class, let's do a quick refresh on how we can test our application using one of the GET requests we have defined.

In our spring-web-demo project, open up the LunchController class. Let's test with the getLunchSpecial() method! Run the SpringWebDemoApplication and then open up Postman, which should have already been installed from the previous module.

Once Postman is opened up, enter in HTTP request mapped to the getLunchSpecial() method in the controller class. Let's use monday as the path variable, so the GET request should be "http://localhost:8080/lunch-special/monday".

Let's see if this works now! Click the "Send" button next to the request.

Looks like the lunch special on Monday is a BLT sandwich! Yippee! Looks like everything works. We'll continue to use Postman as a testing tool. Now let's get into debugging our application.

Conclusion

API clients like Postman are extremely valuable to have in your API developer toolkit. They make it simple to interact with servers by giving you full control over how the response is being sent, with a nice interface for customizing the HTTP verb, URL, headers, and body.

In future lessons, we'll be expanding our API to handle non-GET requests, so being able to use a tool like Postman will make our API development much easier! It's also a great tool to use if you're exploring a third-party API for use in your projects.

Resources

• Postman Documentation