I have looked into why DI doesn’t work when coverage reporting is enabled, and it can be traced back to how Angular detects whether a constructor was present in a class, or if a constructor is generated synthetically, e.g. to initialize class fields. Enabling coverage inserts coverage instrumentation statements into the generated constructors:

class MyLibService extends BaseService {
  constructor() {
    cov_8nt6qq5zt().f[2]++;
    cov_8nt6qq5zt().s[6]++;
    super(...arguments);
    cov_8nt6qq5zt().s[7]++;
    this.foo = 'bar';
  }
}

These prevent Angular from recognizing the constructor as synthesized, causing MyLibService to be instantiated with 0 arguments. The proper behavior would be to delegate to the parent constructor, allowing its dependencies to be injected.

I opened #37811 as a proposal to workaround this issue. It’s not done yet and I can’t give an ETA yet, unfortunately.

tested on angular 8.2.11 with cli 8.3.12 and it is still not fixed, now I have to add tons of workarounds 😦

we are seeing the same issue when using differential loading with v8 and this is breaking in es5 script bundles in IE 11 for specific instances where we have multiple class inheritances without constructor defined in some of the classes.

ex: ` export class A { constructor(public dep1: SomeType){} }

export class B extends A { }

export class C extends B { constructor(dep1: SomeType, dep2: AnotherType){ super(dep1); }

ngOnInit(){ //this.dep1 is undefined here //this.dep2 is defined } } `

I got the same problem. It appears only if tests are running with code coverage: ng test --code-coverage The usual ng test or any type of build (JIT or AOT) gives no errors.

For now the problem can be solved by injecting services on child level and passing them to parent component.