Test: Protocol handler API

[joaomoreno]

Test for #46256:

• windows: @sbatten
• macOS: @weinand
• linux: @ramya-rao-a

Complexity: 3

Authors: @joaomoreno

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Setup

First, make sure your extension sets "enableProposedApi": true in its manifest. Then, get the latest definitions:

1. Change the engine.vscode property to * in package.json
2. Run npm run postinstall
3. Undo step 1

URI Format

Uris directed towards extension vscode.git, for example, all share the following prefix:

{scheme}://vscode.git

(with vscode.git being the extension id).

For example, for VS Code Insiders, these are valid Uris which will be handled by the git extension's protocol handler:

vscode-insiders://vscode.git
vscode-insiders://vscode.git/
vscode-insiders://vscode.git/status
vscode-insiders://vscode.git/clone?url=foobar

Test Details

As an extension author, you can:

• Use the new ProtocolHandler proposed API, to handle such Uris
• Use a new activation event onUri to be activated when a Uri for that extension is opened. This should work in all cases:
  • A Code window is open
  • No Code windows are open, but Code is running (macOS)
  • Code is not running at all
• As a user, you should be prompted to confirm opening Urls directed to extensions

Here's how you can test Uri opening:

• Windows: type explorer URI in a command prompt
• macOS: type open URI in a shell
• Linux: type xdg-open URI in a shell

You can also open a URL from the command line with --open-url URL. This can be used simultaneously with --enable-proposed-api.

[joaomoreno]

I've removed Linux, since URL handlers are not yet supported by Code: #48528