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…]
In the last blog post I showed how you could extend NgbModal to make a Modal Service, letting you re-use modal dialogs easily from within your Angular components. Even though its not always that much fun, I like to try and keep testability in mind when writing code… and, I’ll admit it, sometimes I gloss … [Read more…]
There’s several tutorials for how to use and test HttpClient, but I wanted to distill it down to a simple snippet that I can refer back to when I inevitably forget how to do it. via GIPHY HttpTestingController This handy thing is provided by importing the HttpClientTestingModule in to your TestBed. It lets you manipulate … [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…]
There’s some debate as to whether or not you should test private members in a class. Generally, I fall in to the “if it makes sense to test it, test it” camp. If there’s a private method that is only accessible by a hard-to-mock series of callbacks or events, I would much rather write a … [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…]