Change:
instantiationService.stub(ITextModelService, <ITextModelService>instantiationService.createInstance(TextModelResolverService)); instantiationService.stub(IContextKeyService, instantiationService.createInstance(ContextKeyService)); instantiationService.stub(IListService, instantiationService.createInstance(ListService)); <del> instantiationService.stub(IClipboardService, new BrowserClipboardService()); </del> <ins> instantiationService.stub(ILayoutService, new TestLayoutService()); </ins> instantiationService.stub(ILogService, new NullLogService()); <ins> instantiationService.stub(IClipboardService, instantiationService.createInstance(BrowserClipboardService)); </ins> instantiationService.stub(IStorageService, new TestStorageService()); instantiationService.stub(IWorkspaceTrustRequestService, new TestWorkspaceTrustRequestService(true));

Discussion:
<!-- Do Not Delete This! bugreporttemplate --<!-- Please read our Rules of Conduct: --<!-- Please search existing issues to avoid creating duplicates. --<!-- Also please test using the latest insiders build to make sure your issue has not already been fixed: --<!-- Use Help Report Issue to prefill these. --- VSCode Version: Codespaces OS Version: MacOS Catalina and iPadOS 13 Steps to Reproduce: It seems the Clipboard API is not working, at least using Safari an extension using the which as documented, should be used on Remote Development: Codespaces and install the extension (My extension does exactly that) its command , which will select the word where the cursor is located and should copy the selected text to clipboard to other location command (or use shortcut) ’t work: instead of pasting the the newly selected/copied text, it pastes the previous clipboard content (not created using the extension) I tested on iPadOS 13 and MacOS Catalina and it fails. I tested on Edge (Chromium) and it works perfectly (I guess it should work on Chrome too) I didn’t test on Firefox (yet). BTW, I tried to debug my extension on Codespaces (on iPadOS), but it seems not possible/supported. I’m able to build the extension and hit the Debug button. The Debug toolbar appears but no window/tab appears. Is there a way to debug VSCode extensions right from Codespaces?. <!-- Launch with to check. --Does this issue occur when all extensions are disabled?: Yes
Updated the description and comments. Testing on Edge (Chromium) worked just fine.
Yes, it should open a new tab. Maybe it was blocked?
Hi , Sorry about not updating the description properly. I tested debugging again later (yesterday) and indeed it was blocked by Safari, but only on Desktop (macOS Catalina). On iPadOS, it doesn't display anything (neither a blocked windows warning/icon), so I couldn't debug, yet. I'll update the description. Thanks
I think the safari label should remain, because the issue is happening using Safari, both on MacOS and iPadOS.
It seems the Clipboard API is coming to Safari , we should reevaluate once it lands in Safari stable.
I tested the improvements of api in the latest Safari Technology Preview but it doesn't solve this particular problem.

The copy/paste request is coming from the extension host instead of user action, Safari will then block it.
Just hit this in
verification steps: Open on Safari (bonus points for it being on iPad but it doesn't matter) Install the GHPR extension Go to a random line in a file Run the command Your clipboard should contain the copied permalink now. Bonus points: make sure Edge or Chrome still also work.
Hi , I’m glad to report that it is also working on iPadOS 15.2 and MacOS Big Sur I just tested my Copy Word extension (the reason why I opened this issue) and it is working perfectly. Thank you!