Test: TS extension using our file watchers

[bpasero]

Refs #208872

• Windows @eleanorjboyd
• macOS @paulacamargo25
• Linux @alexr00

Complexity: 4

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So far, the TS extension implemented file watching on their level, leveraging node.js fs.watch and fs.watchFile. With a new setting, this changes to utilise our vscode.fs.createFileSystemWatcher API that is more performant and matches our built-in file watcher.

TS makes extensive use of file watching for the language services to know what kind of types exist for a project. Watch out for error squiggles and problems reported even though a type you use exists on disk.

Steps:

• make sure that typescript.tsserver.experimental.useVsCodeWatcher is configured to true
• use typescript projects as test bed, for example vscode repo itself but also extensions or samples you work on
• as soon as you open a TS file, the extension will activate and file watchers will install
• if you configure log level to trace, a new output channel "File Watcher" gives you verbose information and stats
• do exploratory testing that the TS language services are proper in situation such as:
  • npm install of a new module with types that you reference from your code
  • switching back and forth between branches with differing state of TS types
  • defining a new type in a new file and then using it in another file
  • deleting a file with types that are used
• open an empty workspace (no folder) and open a TS file (e.g. from VSCode repo) and verify that changes are also picked up in that case for types you reference
• keep an eye on the window and main logs that the file watcher does not crash or restart

[karthiknadig]

I have the log level set to trace:

I don't see a "File Watcher" channel, I tried reloading as well.

[bpasero]

@karthiknadig you need to set the overall log level to trace, not just for TS 👍