Using signals in render template should automatically apply to component

[NateRadebaugh]

The closest I'm seeing is this example, but it has some issues:

https://github.com/testing-library/angular-testing-library/blob/main/apps/example-app/src/app/examples/22-signal-inputs.component.spec.ts

1. Only model can be updated, which would require us to change our components from input for anything we want to test, which is not ideal
2. Manually interacting with the underlying values like that is testing implementation details
3. The template syntax in render doesn't expose an underlying componentRef to call setInput on

In an ideal world, the template will automatically update when the signal changes, like we'd expect in angular template HTML:

Preferred API:

  it("should render text from a signal", async () => {
    const someSignal = signal("hello");

    await render(
      html`<span data-testid="value">{{ someSignal() }} world</span>`,
      {
        componentProperties: {
          someSignal,
        },
      },
    );

    // Passes
    expect(screen.getByTestId("value")).toHaveTextContent("hello world");

    someSignal.set("updated");

    // Fails
    expect(screen.getByTestId("value")).toHaveTextContent("updated world");
  });

[timdeschryver]

Hello, sorry I missed the notification for this issue.

I agree that would be nice to do, unfortunately Angular's setInput API doesn't work nicely with Signals. Because of this, it doesn't work for ATL and I don't think it's a good idea to patch this behavior on our side.

For now, you should be able to work around it by accessing the signal through the test fixture.

https://github.com/testing-library/angular-testing-library/blob/main/apps/example-app/src/app/examples/22-signal-inputs.component.spec.ts#L45

[timdeschryver]

This should be fixed by #547