Test Your Promises
Now letâs explore testing for promises in code running within Node.js. The same techniques work for client-side code that use promises as well. Weâll start with a short introduction to promises and then dive into testing code that uses promises.
A Short Introduction to Promises
Before digging into testing promises, letâs review how promises worksâI promise to keep it short.
Traditionally asynchronous functions have used callbacks. But callbacks have a few drawbacks. Callbacks have to be registered before the asynchronous functions generate any response. For example, when using an instance of XMLHttpRequest, calling the send function before registering a callback with the onreadystatechange property may result in some ...
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