So there I am, happily writing unit tests, and suddenly this appears I keep seeing this error while trying to write Angular tests. I… *think* this happens when something goes wrong during the constructor of a component. I’ve written before about how it could be due to an @Input property not being initialized properly. But, … [Read more…]
Recently, I was writing some unit tests for Angular. It was a pretty basic test, just checking to see if a method on an injected provider was called when a method in my component executed… but suddenly everything blew up with this weird error: TypeError: Cannot read property ‘ngInjectableDef’ of undefined Googling around didn’t really … [Read more…]
Sometimes when you’re writing Javascript unit tests you have to give Javascript a chance to catch up before checking your assertions. Javascript uses a single event loop, so it isn’t multi-threaded in the same way as other languages. You can still get a “multi-threaded feel” by using callbacks (promises, observables, etc), but at the end … [Read more…]
Recently I wrote some code that contained a setTimeout. The reason was so that the UI could catch up before the function actually fired – something that I’ve found the need to do with javascript from time to time. So, when it comes to testing the code… my test just skipped along until it literally … [Read more…]
In a previous post I talked about testing Observables in your Angular code. This is pretty common, because HttpClient sends back an Observable<T> – so if you want to spyOn that function, you’ll need to figure out how to return an Observable. I’ve been bouncing around a couple of projects/repos recently, and it turns out … [Read more…]
Recently I was updating and fixing some existing unit tests after doing a (rather large) overhaul of code.The unit test previously needed to wait for an asynchronous callback to finish before continuing, something like this: Note the optional done parameter provided to beforeEach. This is a void function that signals Jasmine that the callback is … [Read more…]
In Jasmine, you can expect an object toBe another object. However, this will check to see if the two arrays point to the same reference object. In other words, it will check to see if the arrays point to the same memory address. Produces this not-very-helpful error message: Expected [ 42, ‘Forty-Two’ ] to be … [Read more…]
Recently I had a problem where in an Angular unit test where I had an object that was being initialized in ngOnInit from a service. As far as I could tell, everything should be working, but the test would fail because I was trying to set a property on the object before it had finished … [Read more…]
I find that writing unit tests in JavaScript kind of sucks, so this post will (hopefully) serve as a cheat sheet of all the stuff I keep looking up. As such, it will be updated as I learn new stuffs. How To: scope test run to specific tests Remember to set it back before you … [Read more…]
I was trying to be good and keep up with my Karma unit tests in my Angular 5 Typescript project, but I was running in to a really weird error that left a lot to be desired: The logs in the console window are not helpful either… Chrome 63.0.3239 (Windows 10 0.0.0) ERROR Uncaught NetworkError: … [Read more…]