How do I test an angular dart decorator? - dart

Question

I am trying to unit test an angular dart decorator but cannot pass the component compile phase.
I am trying to follow this example : https://github.com/vsavkin/angulardart-sample-app/blob/master/test/unit/agenda_item_component_test.dart
The problem is that karma doesn't seem to wait for the compile phase to finish and just skips the test.
part of webpuzzle_spec;
digest() {
inject((TestBed tb) {
tb.rootScope.apply();
});
}
compileComponent(String html, Map scope, callback) {
print("This logs");
return async(() {
inject((TestBed tb) {
print("this should log but doesn't");
final s = tb.rootScope.createChild(scope);
final el = tb.compile(html, scope: s);
microLeap();
digest();
callback(el.shadowRoot);
});
});
}
testWpDropdownMenu() {
group("[WpDropdownMenu]", () {
setUp(setUpInjector);
tearDown(tearDownInjector);
setUp((){
module((Module _) => _..type(TestBed)..type(WpDropdownMenu));
});
html() => '''<span class="dropdown-toggle">
<button type="button" class="btn btn-default">menu to click</button>
<ul class="dropdown-menu">
<li>menu item</li>
</ul>
</span>''';
test("should open menu on click", compileComponent(html(), {}, (shadowRoot) {
print("this never logs :(");
shadowRoot.click();
digest();
var toggleableMenu = shadowRoot.querySelector('.dropdown-menu');
expect(toggleableMenu.style.display, equals('none'));
expect(true, equals(false)); // this should make the test fail
}));
});
}
What is the problem with this code ? Is there a nice example somewhere that explains how to test a component/decorator, only using angular.dart and karma ?