hasStyle / doesNotHaveStyle: empty expected should throw

[buschtoens]

I've encountered usages like this in the wild:

test('button can toggle color', function(assert) {
  await render(hbs`<ToggleColorButton class=".btn" @on="#00FF00" />`);
  
  // toggle on the button
  await click('.btn');

  // button has `on` color
  assert.dom('btn').hasStyle({ backgroundColor: '#00FF00' });

  // toggle the button off again
  await click('.btn');

  // `on` color has been removed
  assert.dom('btn').hasStyle({});
});

The last LOC incorrectly assumes, that hasStyle({}) asserts that all "custom" styles have been removed. In reality hasStyle({}) does not assert anything:

https://github.com/simplabs/qunit-dom/blob/2a73e56344829a6f1fd3b28cd5df6b4ee1d00b75/lib/assertions.ts#L583-L586

I would suggest to throw an error or fail the assertion, when an empty object is passed to hasStyle, as this can never be a valid assertion and is most likely a mistake of the author of the test.

[Turbo87]

agreed, seems reasonable to show a helpful error message in those cases 👍