`cypress/angular-signals` support for `InputSignalWithTransform`

[bohoffi]

What would you like?

#29264 brought support for the assignment of pure InputSignal which works fine as long as you do not plan on working with InputSignalWithTransform like:

public readonly enablePreview: InputSignalWithTransform<boolean, unknown> = input(false, {
  transform: booleanAttribute
});

Why is this needed?

The componentProperties of MountConfig<T> from cypress/angular-signals needs to be updated from

componentProperties?: Partial<{
        [P in keyof T]: T[P] extends InputSignal<infer V> ? InputSignal<V> | WritableSignal<V> | V : T[P];
    }>;

to

componentProperties?: Partial<{
        [P in keyof T]: T[P] extends InputSignal<infer V> | InputSignalWithTransform<infer V, unknown> ? InputSignal<V> | WritableSignal<V> | V : T[P];
    }>;

I'd be willing to provide a PR adding the missing type.

[AtofStryker]

@bohoffi thank you for opening this issue. I think InputSignalWithTransform was included in Angular 17 and we should be able to add this to the Cypress 14 release if that is the case. We will be merging the cypress/angular-signals harness upstream into cypress/angular for Cypress 14.

[bohoffi]

@AtofStryker yes, InputSignalWithTransform was introduced with Angular 17.2.0 (PR 54053).

Thank you for taking it into account for Cypress 14 🙏
Having it will resolve our as unknown as workaround :)

[AtofStryker]

@bohoffi I'm taking a look into this today. It looks like supporting the type is trivial, but the transform on the input signal doesn't actually get called mainly because of how we handle signals in the test harness via Inferred Generic Type or Writable Signals https://docs.cypress.io/app/component-testing/angular/examples#Testing-Signals.

I can go ahead and fix the type, but it looks like its very hard to access the transforms and alias declared on the input signal since it lives in an internal symbol

[bohoffi]

@AtofStryker I'll see if I can find some time to look into it myself to find something to work with.

[vmasek]

Hello, is the current state still that CCT do not works with signal input transform?
From what I understood the transform function is never called, is that still a case?

What is proffered workaround, would a transform be called if I tested with a component that wraps the actual component I want to test and binds the input from template?