NgTestBed can't infer type of createXXFactory()

[GZGavinZhao]

Consider the following code (from _tests/test/common/directives/for_test.dart):

// for_test.dart
void main() {
  group('ngFor', () {
    tearDown(() => disposeAnyRunningTest());

    test('should reflect initial elements', () async {
      var testBed = NgTestBed(ng.createNgForItemsTestFactory());
      var testFixture = await testBed.create();
      expect(testFixture.rootElement, hasTextContent('1;2;3;'));
    });
  );
}

@Component(
  selector: 'ngfor-items-test',
  template: '<div><copy-me *ngFor="let item of items">'
      '{{item.toString()}};</copy-me></div>',
  directives: [
    CopyMe,
    NgFor,
  ],
)
class NgForItemsTest extends BaseTestComponent {
  @ContentChild(TemplateRef)
  TemplateRef? contentTpl;
}

An analysis error is thrown on NgTestBed: Couldn't infer type parameter 'T'. However, when checking the generate template code, the function createNgForItemsTestFactory() clearly returns a type that is not dynamic:

ComponentFactory<import1.NgForItemsTest> createNgForItemsTestFactory() {
  return ComponentFactory('ngfor-items-test', viewFactory_NgForItemsTestHost0);
}

where import1 is imported as import 'for_test.dart' as import1;

This is not a huge problem as the developer merely needs to change NgTestBed into NgTestBed<NgForItems>, but this can be very counter-productive for those working on old code (like us), which stops them from performing analysis on the packages (25b75dd).

Dart SDK: 2.17.0
AngularDart: 7.1.0
OS: agnostic
Browser: n/a

[IgorBabalich]

Fixed this as part of changes for #7
This task can be closed.
Thanks

[GZGavinZhao]

@IgorBabalich Did you change any code, or did it just magically work?