Angular单元测试中Testbed.inject(serviceName)和fixture.debugElement.injector.get(serviceName)的区别

Question

I was going through the test cases written by my team members. What I observed was at some places they've used TestBed.inject(serviceName) for injecting the service and at some places they've used fixture.debugElement.injector.get(serviceName) . Can somebody tell me the difference between these two? Also what is the correct way of injecting services?

For eg:

let abc: ABCService

Technique 1: abc = TestBed.inject(ABCService) Technique 2: abc = fixture.debugElement.injector.get(ABCSerice)

Thanks in Advance

Answer 1

I think they are essentially the same thing. I only use Technique 1 .

In older versions of Angular, it was TestBed.get but now it is TestBed.inject .

I think TestBed.inject gets the service from the root injector while fixture.debugElement.injector.get gets the service that is actually injected into the component.

You can read more about it here .

You can provider a service in the Component decorator of a Component and each instance of this service will be unique (a separate instance) and I bet fixture.debugElement.inject.get will get this unique instance provided in the decorator as opposed to the global singleton. Check out providers in decorators here .