Add "owner" reserved word warning

[jrowlingson]

After running ember-qunit-codemod against our app I observed that a test was falling with the following message:

TypeError: Cannot read property 'apply' of undefined

The relevant potion of the affected test:

  test('it displays the project owner', async function(assert) {
    this.set('owner', 'some_username');
    await render(hbs`{{project owner=owner}}`);
    
    ...
    
  });

It looks like this is now falling because the owner property is now set within the test context (https://github.com/emberjs/ember-test-helpers/blame/0cacde9a1ba308409394b18f3705e60499955b45/addon-test-support/%40ember/test-helpers/setup-context.js#L90
).

I am not sure what may be the best way to handle this, but, I am thinking adding a check prior to setting owner may be helpful.

[Turbo87]

That seems like a good idea. We should probably warn whenever someone tries to set owner, element or any of the other keywords.

Or we make this.get/set() operate on a different context, though that might be confusing 🤔

[rwjblue]

Yep, totally happy with this. But not quite sure how to implement. I suppose we could swap from normal property sets to Object.defineProperty with a setter that throws a helpful error?

[Turbo87]

can't we do that check in the .set() function that we put onto this?

[rwjblue]

Sure, but won’t catch most cases. I don’t think most folks go through set unless required...