fillIn does not work with input values that are decorated with the readonly helper

[kboucher]

ember-cli: 3.28.5
@ember/test-helpers: 2.6.0

I have an input in a component that is leveraging the readonly helper for one-way binding:

<input
    type="text"
    value={{readonly this.inputValue}}
    {{on "change" (fn this.onValueChange @condition)}}
>

...however, when I try to use the fillIn helper in an acceptance test, the input is not filled in and the change and input events are not fired.

Removing the readonly helper results in the fillIn helper working as expected.

Works:

<input
    type="text"
    value={{this.inputValue}}
    {{on "change" (fn this.onValueChange @condition)}}
>

[kboucher]

Turns out the issue was actually a bug in my code that did not manifest itself until my test case. Testing FTW!