utils/bind-data-test-attributes: Handle failing `set()` with assert instead of warning

Reference Commit After experiencing some issues after trying to add a data-test-selector to tagless components, I realized afterwards, by looking at the commit on master, that a warning was created to give some information. This is a great idea, but maybe not explicit enough (I didn’t see this warning, in the middle of other warnings). If you agree, I can make a PR to make an assert instead of a warn, to be more explicit and to force the user to fix it as soon as this is done. What do you think?

[Turbo87]

We could add a supportsDataTestProperties property that a) will disable the tagName == '' check and b) will be removed by an AST transform so that it doesn’t exist in prod builds. If we do that we wouldn’t even need to revert the current behavior and could keep using assertions, and we could adjust the assertion message to hint about this workaround. PRs welcome 😉

[marcoow]

🤦‍♂️ looking at #291 I realize there’s another case where you use a non-Glimmer component with tagName and still want to be able to pass data-test- etc. to forward those to child components. I guess we could change the assertion so that it checks whether the attributes are present on the prototype first before triggering the warning?

So if you explicitly defined the attributes you could opt-in to accepting data-test- attributes without triggering the warning, e.g.

export default Component.extend({
  tagName: '',
  data-test-attr: null,
  …
});