How to Fake a Route Change in an Angular Unit Test

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This isn't something that's come up too often in my experience with Angular, but sometimes I've needed to write code that subscribes to Router.events and takes action based on the current route.

But how do you test something like that in a unit test? The key is by using a Subject, which is a kind of Observable, and exposes a next() method, which allows us to simulate a route change. Here's an example:

    const event = new NavigationEnd(1703, `/account/orders/${orderId}`, '/');
    (router.events as Subject<Event>).next(event);

By casting Router's events property as a Subject, we can call next() with our NavigationEnd event, and simulate the route change.

For the Event type, make sure you are importing Event from @angular/router.

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