Everybody how tried to write some tests for container ccomponents knows the pain of writing the mocks. This can be very time consuming, since you have to write Mock classes for each used components including inputs etc. The possibility of NO_ERRORS_SCHEMA should NOT be used, since it is suppressing ALL error messages concerning the schema. It is just an option to lead testing ad abdsurdum …
BUT I found a nice module which is a very nice solution: ng-mocks. Mocking a component is then a oneliner in the TestBed configuration:
import { MockComponent } from 'ng-mocks';
// ...
declarations: [
TestedComponent,
MockComponent(DependencyComponent),
]