I was happy to find out that Jest had methods (matchers) for checking errors. In hindsight, it makes perfect sense and is something that should be there. I guess being a newbie makes you impressed with things that are not so impressive, per se. toThrow.
One challenge I faced was that I didn’t know I had to wrap the generateQuiz function in a function to use toThrow. I saw the answer in the docs though.
Doing the error checks was cool and pretty smooth
I also used some nice matchers for working with numbers, like toBeEqual and toBeGreater than. Again, it shouldn’t have surprised me to see them there, but it just gave me this feeling, a happy feeling that Jest is a complete tool that you can use to cover a lot of cases.
Things got interesting when I began writing tests for the outputs. I was looping through the question object (which is an array of objects), and I tried using forEach. forEach wasn’t working as I expected, and after several tries, it hit me that it wasn’t the right tool for the job. Since I needed to know if the array passed a condition, I needed to use the every function. Alhamdulillah, it eventually worked.
Fun fact: I built some utility methods to help me work with the array of objects.
Unit testing can bring to light things about your code you didn’t know. I thought all the options needed to be part of options bank, but I was wrong. In short, the questions bank doesn’t need to be a subset (proper or not) of the options bank. In another short, I mean the answer (sound) doesn’t need to be in the options database.
Alhamdulillah, using the library in my quizzes didn’t require much code changes. A few renames here, property changes there, and everything was working fine.
I want to separate the tests, and from what I saw in the docs, I can group similar tests using describe, so that’s one.
I want to see if there’s room for improvement, whether some tests are useless or not
I also want to document my library using JSDocs syntax
And finally, I want to make it easy to import in my quizzes. Jest only has experimental support for ES6 modules, so I use CommonJS module syntax for the library, which I then have to change to ES6 modules when I use the library in my quiz apps. It’s not too stressful, but it’s a bit annoying.