Select - no longer update value while navigating dropdown

[atmgrifter00]

Pull Request

🤨 Rationale

While in the midst of implementing the clear select feature, I recognized that the fact that we were updating the value while navigating the dropdown was both confusing (since we don't update the display value) and resulting in an awkward implementation for the feature.

👩‍💻 Implementation

While we no longer want to update selectedIndex (and as a corollary to this, value) while a user navigates the dropdown, we still want the appropriate option in the dropdown to appear selected/highlighted. The styling was keying off of the state of the aria-selected attribute, which was being updated when the selected state of an option changed. Now, as the selected state is no longer changing, I've created a new attribute for the ListOption, activeOption, that the CSS for the Select leverages to manage the styling of the options.

To set the new attribute at the appropriate times required providing overrides to the various select<>Option (Next, Previous, First, Last) methods. In order to accomplish this we have to keep some additional internal state for what the current active index is (the index for which option should currently be highlighted).

It was also discovered during the implementation of this fix that there was an issue stemming from the typeahead feature that allows a user to select an option (when there is no filter, or when the dropdown is closed) by typing characters while the Select has keyboard focus. This required forking some FAST Listbox implementations to prohibit updates to the selectedIndex while the dropdown was open.

Additionally, since I was already updating related implementation, I was able to tackle this issue as well (where tabbing away from the Select could end up with unexpected display).

🧪 Testing

Largely this just required updates to tests that used to expect the selectedIndex/value to change while the dropdown was open and a user performed a navigation within the dropdown. Beyond that I provided new tests for the <Tab> behaviors, new tests to verify the typeahead behaviors, and a slight update to the pageObject for reporting what the selected option is (based on whether or not it's open). This last point could be subject for debate.

✅ Checklist

• I have updated the project documentation to reflect my changes or determined no changes are needed.

[atmgrifter00]

@mollykreis would you mind buddying this?

[rajsite]

Didn't finish reviewing today, expect to Monday