refactored onKeyDown to be easier to read, and added test

[brandonrainey]

#918

Changed the onKeyDown function in search-display-controller to be easier to read. Also created a new test file to test preserved behavior between the current and new function.

The test passes, but I'm not sure if the test is up to par or not, but I tried to replicate as well as I could figure out how to.

[Kuuuube]

Add this to the tests:

ctrl + a
alt + a
meta + a
backspace
ctrl + backspace
arrow key down

[jamesmaa]

Thanks for doing this 😄

My biggest concern stems from replicating the search-display-controller logic in the tests because even though they verify the correctness of the current yomitan, if the logic of those if statement changes in the future, we would need to update the corresponding tests, which I don't expect future developers to remember to do.

[Kuuuube]

It would also be good to include this test in the package.json. Maybe something like this:

"test:search-display-controller": "vitest run --config test/data/vitest.search-display-controller.config.json",

With test/data/vitest.search-display-controller.config.json looking like this:

{
    "test": {
        "include": [
            "test/search-display-controller.test.js"
        ]
    }
}

Then npm run test:search-display-controller can be added to "test" command in package.json as well.

[Kuuuube]

Actually disregard the part about adding a specific script for this in the package. It's probably not important enough to need that. It runs with test:js anyways.

[Kuuuube]

Thank you for taking the time to add this!