Clear scrollback on terminal clear in watch mode

[ColCh]

simply tweak clear codes and check 'em in different envs
main purpose was to clear scrollback buffer, instead of just clearing screen

Summary

clear scroll back on watch mode. helps a lot if you have output which you want to scroll up

Test plan

tested with this diff just to show that I have patched version of jest running:

diff --git a/packages/jest-cli/src/jest.js b/packages/jest-cli/src/jest.js
index f499dd3..77ff3e1 100644
--- a/packages/jest-cli/src/jest.js
+++ b/packages/jest-cli/src/jest.js
@@ -285,6 +285,7 @@ const runCLI = (
   argv = argv || {};
   if (argv.version) {
     pipe.write(`v${VERSION}\n`);
+    pipe.write(`PATCHED VERSION FROM 1861-clr-scroll-on-watch\n`);
     onComplete && onComplete();
     return;
   }

on each test, I have to add jest/packages to NODE_PATH and do npm link inside of jest/packages/jest-cli, to make patched jest available globally

then run jest --version just to ensure that I'm running my patched version, and then, finally, run jest --watch

checked on:

• OS X with zsh
• Windows 7 with cmd
• Ubuntu with bash

(sorry, no videos nor gifs. removed them)

I think I have not break anything with this change. However, windows 10 with powershell is untested. Do you want me to test it also, @cpojer ?

And, cc @gaearon , please take a look on this PR.

P.S. However, I don't have GUI Linux and can't check on it...

[ColCh]

And, yup, this PR is related and should close #1861

[codecov-io]

Current coverage is 89.36% (diff: 100%)

Merging #2230 into master will not change coverage

@@             master      #2230   diff @@
==========================================
  Files            39         39          
  Lines          1467       1467          
  Methods           0          0          
  Messages          0          0          
  Branches          0          0          
==========================================
  Hits           1311       1311          
  Misses          156        156          
  Partials          0          0          

Powered by Codecov. Last update 88cdb51...a7a51d8

[gaearon]

I'll take a look at this next week. I want to test it thoroughly but my schedule is just too packed right now and I need more time.

[SimenB]

Will this work correctly in a tmux pane as well?

[ColCh]

@SimenB yes. from 1.6 version

link to tmux changes file:
https://github.com/tmux/tmux/blob/23254f59daea7415c96bc323d3b48d35c1b21327/CHANGES#L391-L392

Support for \e[3J to clear the history and send the corresponding
terminfo code (E3) before locking.

[SimenB]

Awesome, thanks for digging that up!

[gaearon]

LGTM.

[github-actions]

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