cli: Hide Watch Usage output when running on non-interactive envs

[taylon]

Summary

Watch Usage options are useless in non-interactive environments (like Docker). Currently jest-cli is smart enough to know that it should not clear the terminal in those environments, with this PR it will also not output Watch Usage related stuff either, making the UI cleaner.

Also, because the terminal is not cleared after a test run, the subsequent runs will not print a new line after the "Press w to show more" text, which makes it hard to read and a really bad UX once you have watch running for a couple of test runs.

I'm not familiar with the code base at all, so let me know if there is anything that should be done differently and I'll fix it =D

Test plan

Output in interactive environments is not affected.
Here is how the output looks in Docker before and after this PR:

Before:

After:

[rogeliog]

NIT: I think we could name this file is_interactive so that the import looks like 'import isInteractive from './is_interactive'...

I could even be nice if this was in something like jest-util and then we could use it in other places of the codebase like

packages/jest-cli/src/pre_run_message.js
packages/jest-cli/src/reporters/__tests__/default_reporter.test.js
packages/jest-cli/src/reporters/coverage_reporter.js
packages/jest-cli/src/reporters/default_reporter.js
packages/jest-cli/src/watch.js
packages/jest-util/src/clear_line.js

[rogeliog]

Looks good!

One small comment if you are running jest in watch mode within Docker. You could pass the -it flags and then it would make it interactive docker run -it my-image yarn test

[cpojer]

Thanks for sending a PR. Can you make sure "yarn test" passes? :)

[taylon]

I renamed and moved isInteractive to jest-util and also replaced usage of process.stdout.isTTY && !isCI with it.

I couldn't figure out why tests are failing in circleci though. Locally I tried yarn test, yarn test-ci and yarn test-ci-partial and everything passes. Do you guys have any idea of what could be wrong?

[SimenB]

Do they pass when you do CI=true yarn test? Or somehow emulate the terminal on CI

[taylon]

Thanks @SimenB that was exactly it =D

Tests are passing now, I also added tests to is_interactive.
CircleCI is failing because of a yarn error and I can't trigger another build manually, that should be passing though.

[SimenB]

I triggered a new CI run.

Can you update the changelog?

[github-actions]

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