Angular Unit Test shows error warnings of kind NG0304 "component is not a known element" even...

I am writing unit tests for an Angular component that uses multiple child components which are used with @ViewChild({}) in the following way:

Template:

...
<app-app-form></app-app-form>
<app-terms-form></app-terms-form>
...


Model:

...
@ViewChild(AppFormComponent, {static: true}) protected appForm: AppFormComponent;
@ViewChild(TermsFormComponent, {static: true}) protected termsForm: TermsFormComponent;
...


In total I use six such components. For testing purposes I declared component stubs in this way:

@Component({
selector: 'app-terms-form',
template: '',
providers: [
{ provide: TermsFormComponent, useClass: TermsFormStubComponent }
]
})
class TermsFormStubComponent implements Partial<IFormComp<any>> {
...
}


When I run my tests I get error warning messages for all used child components although I declared them in the TestBed:

ERROR: 'NG0304: 'app-terms-form' is not a known element (used in the 'CreateLicenseComponent' component template):
1. If 'app-terms-form' is an Angular component, then verify that it is a part of an @NgModule where this component is declared.


I want my tests to not display any error warnings for things that I deem already fixed but I can not figure out how to stop it. The TestBed is configured with all the necessary components.

beforeEach(async () => {
...
await TestBed.configureTestingModule({
imports: [ ... ],
schemas: [ CUSTOM_ELEMENTS_SCHEMA, NO_ERRORS_SCHEMA ], // doesn't resolve the error warnings NG0304
declarations: [
CreateLicenseComponent,
OrderFormStubComponent,
DeviceFormStubComponent,
AppFormStubComponent,
TermsFormStubComponent,
DnFormStubComponent,
ExpiresFormStubComponent
],
providers: [ ... ]
})
.compileComponents();

fixture = TestBed.createComponent(CreateLicenseComponent);
component = fixture.componentInstance;
fixture.detectChanges();
});


As you can see I already added CUSTOM_ELEMENTS_SCHEMA and NO_ERRORS_SCHEMA, also tried each individually. But it doesn't work. And I should not have to add them in the first place because all needed elements are in the "declarations" array. I still get the error warnings for all six child components

My tests run all successfully and through debugging I already confirmed that the component stubs are available. I could just ignore these error warnings but they are nevertheless annoying in particular because I am going to add more components like the showcased one. Does anyone have an idea how to cleanly solve this problem?

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