activeTerminal undefined for first terminal even when visible

[andycraig]

When there are no terminals, and then a terminal is created and shown with the following code, the terminal is visible but vscode.windows.activeTerminal is still undefined. Once a second terminal has been created, activeTerminal works fine.

const myTerminal = vscode.window.createTerminal(`My Terminal #${NEXT_TERM_ID++}`);
myTerminal.show(true);

• VSCode Version: 1.48.2
• OS Version: Windows 10
• Version: 1.48.2 (system setup)
• Commit: a047975
• Date: 2020-08-25T10:13:11.295Z
• Electron: 7.3.2
• Chrome: 78.0.3904.130
• Node.js: 12.8.1
• V8: 7.8.279.23-electron.0
• OS: Windows_NT x64 10.0.18362

Steps to Reproduce:

To try to make a minimal reproducible example, I have made a small change to one of the Extension Samples. You can see my modification to the Microsoft version here: https://github.com/microsoft/vscode-extension-samples/compare/master...andycraig:master?expand=1

1. Download/clone my version from https://github.com/andycraig/vscode-extension-samples/tree/master

2. File -> Open Folder... -> vscode-extension-samples/terminal-sample

3. Run -> Start Debugging

4. Close existing terminal

5. Command Terminal API: Create & Show Terminal

6. Observe terminal appears, and message 'onDidOpenTerminal, name: My Terminal Open Source VS Code #1'

7. Command Terminal API: Check activeTerminal

8. Observe message 'activeTerminal is undefined'

   Unexpected, as 'My Terminal Open Source VS Code #1' is visible.

9. Command Terminal API: Create & Show Terminal

10. Observe terminal appears, and message 'onDidOpenTerminal, name: My Terminal gulp-symdest does not preserve links on electron #2'

11. Command Terminal API: Check activeTerminal

12. Observe message 'activeTerminal: My Terminal gulp-symdest does not preserve links on electron #2'
    This is as expected.

If 'My Terminal #2' is closed, activeTerminal correctly becomes 'My Terminal #1'. If this is closed, and the steps repeated, the message 'activeTerminal is undefined' will appear again.

Things DO work as expected if the terminal is created and shown with Terminal API: Create Terminal and Terminal API: Show, then verified with Terminal API: Check activeTerminal: this produces the message 'activeTerminal: Ext Terminal #1'. So it seems somehow specific to the code at the top of this issue.

Does this issue occur when all extensions are disabled?: Yes

I identified this while following up on a discussion at #105944. There are some activeTerminal issues that look related, like #53107, but I couldn't find one describing this problem.

[cyrilletuzi]

I'm the author of the Angular Schematics extension (400 000+ users), and I'm also facing an issue with unreliable vscode.window.activeTerminal.

But the issue seems much larger than what is described here, for me the activeTerminal API is totally buggy.

For short, my extension is using a terminal to launch Angular CLI commands, and I would like to switch back to the previously active terminal (generally there will be a terminal with npm start / ng serve running) once it's done. See cyrilletuzi/vscode-angular-schematics#396

So I'm storing vscode.window.activeTerminal to show it back after, but the value is rarely right.

For example, if I open a terminal, launch any command (like echo 'world'), then open another terminal (with the "+" button), launch any command, then use my extension, the first terminal will be displayed back instead of the second.

Things get more and more messier if I delete terminals, add new ones, switch between them, etc.

Seems to me there is a lot of cases where vscode.window.activeTerminal is not updated at all. When looking in the repo issues, I've seen quite of a lot of related issues closed while not really being fixed.

@Tyriar as you tagged this issue, do you know what's the status about this issue and this API in general?

[cyrilletuzi]

For info, it's back to normal in VS Code 1.53. So I'll unsubscribe from this issue.

[andycraig]

@cyrilletuzi Thank you for the update!

I have tested in VS Code 1.53 too and the bug I reported no longer happens. The active terminal is now the visible terminal, as expected. I will close this issue. @Tyriar If you fixed this, thank you!