get is deprecated: from v4.0.0 use Type<T> or InjectionToken<T>

Question

After switching to Angular 5.2.3, and running ng cli with a linter rule of "deprecation": true i get the following error in many of my tests:

get is deprecated: from v4.0.0 use Type<T> or InjectionToken<T> 

The line that complains is something like

fixture.debugElement.injector.get(MyService) 

with MyService being a class used for dependency injection.

I am at a loss to guess what the new syntax is supposed to be, as

fixture.debugElement.injector.get<MyService>(MyService) 

gives a compile error that Argument of type 'typeof MyService' is not assignable to parameter of type 'Type<MyService> | InjectionToken<MyService>'.

What is the correct way to use the injector to avoid deprecation errors?

Edit: See answer below, for Angular9 update.

Edit: It seems to be related to MyService being an abstract class. If I use a non-abstract class, the .get<T>(T) syntax works.

Edit: Fix is apparently pending some PR work - https://github.com/angular/angular/pull/25222

Answer 1

A better you can try to convert your service as Type and then use injector like this:

import { Type } from '@angular/core';  fixture.debugElement.injector.get<MyService>(MyService as Type<MyService>) 

Answer 2

UPDATE: For Angular9, the syntax has changed to this:

TestBed.inject<IDataService>(IDataService).

This also works for abstract classes.

In VSCode, you can fix most of your cases by this

FIND: TestBed.get\(([^\)]+)\) as .*; REPLACE: TestBed.inject<$1>($1); 

---

PRE Angular 9. So, it seems to be related to Abstract vs non-abstract classes.

I have posted my findings here: https://github.com/angular/angular/issues/22063 in case someone runs into the same issue.