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…]
Recently I was trying to write a unit test testing to see if one object was equal to another. The objects themselves were simple, just a collection of built-in types, so it should be easy to test. .Equals However, since I didn’t implement .Equals, C# doesn’t natively know how to check if the objects are … [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…]
The C# Interactive window allows you to use a C# REPL that can be pretty useful for testing something out quickly. I’ve used it a bunch of times for formatting a DateTime to a string, because I can never quite remember which combination of characters results in what I want. In Visual Studio, you can … [Read more…]