Ensure app_uri.txt is cleaned up when Rails server shuts down

[andyw8]

The app_uri.txt file should only exist when the server is running. The extension uses its presence to report if the server is running or not. If the server is not running, some of the extension features will not be available.

🎩 completed.

[st0012]

👍

[vinistock]

I'm not sure I understand. We check if the server is running by making a request to it.

But we need to ensure that app_uri.txt exists because otherwise we don't know the URL we need to make requests against.

The extension currently complains if app_uri.txt doesn't exist because we wouldn't know which URL to make requests against.

The idea of that error was for it to show up once and then after restarting the server the file would exist and you'd never need to do it again.

[st0012]

What do we gain from keeping it there even when the server is not up anymore?

If you had previously run ruby-lsp-rails with your server and then shut it down, the file would be left there. So the file check would not be raised correctly even though the server is not up anymore.

[vinistock]

Well, in my head the question is inverted. Why add extra code to clean this up if we always need to know the app's URL and port?

Adding extra code can always bring up unexpected maintenance. For example, what happens with this at_exit hook if someone decides to delete the file while the server is running? Will it raise? And in that case, what's the state of the server?

Checking if the server is running based on the file is more brittle than actually making a request and verifying that it is responding.

[st0012]

As long as our implementation still relies on the file's presence as a state, either for error like now or just a warning like in #88, we should make sure the state doesn't leak to another run.

If we don't do things based on File.exist?(app_uri_path) anymore, I'm fine with leaving it uncleaned.