Testing `textDocument/didClose` in extensions requires a three minute timeout

When opening a file in tests using vscode.workspace.openTextDocument followed by vscode.window.showTextDocument and closing it again using workbench.action.closeAllEditors or workbench.action.closeActiveEditor, a textDocument/didClose notification is not fired until three minutes have passed since the file was opened. I assume this happens for the same reason as the three minute timeout in #652.

While it's possible to test functionality that depends on a didClose notification with a three minute pause, it's not ideal. Is there a way to open (or close) files in extension tests that fires the notification sooner?

In case it helps, I've also put together a small reproducer. Just compare the behavior of manually opening foo.txt in the file tree and closing it after the language server has started with what the test does.

Tested on VS Code version 1.70.2.

Start with the extension-test sequence using vscode.workspace.openTextDocument, vscode.window.showTextDocument, and workbench.action.closeAllEditors or workbench.action.closeActiveEditor. Compare it with the manual workflow described in the issue and inspect the linked didClose reproducer. Done means an extension test can trigger textDocument/didClose without waiting three minutes.