Extend `updateConfigAndRun` to allow change of `verbose` and `collectCoverage`

[tdd]

🚀 Feature Proposal

The current scope of accepted config keys is super narrow (and the documentation doesn't say anything about it).

Motivation

The two most asked-for watch plugins that are not yet implemented are:

• toggle coverage collection
• toggle test verbosity

Both are trivial to implement, provided that the passed updateConfigAndRun() function takes the relevant global config keys into account. Currently, it only accepts the minimum set of config keys required to implement the internal plugins, not one more. Fortunately, this was enough to implement the typeahead plugin, as it's just an overwrite of the logic for the non-typeahead internal plugin, but that's as far as it goes.

Note that IMHO, the global config should be audited for prime candidate keys that seem innocuous enough to expose to watch plugins. It's likely that bail, collectCoverageFrom, collectCoverageOnlyFrom, coverageDirectory, coverageReporters, notify, notifyMode, onlyFailures and reporters would be good candidates that do not impede core's ability to function when tweaked.

Example

• Being able to toggle collectCoverage would let us implement a coverage toggler
• Being able to toggle verbose would let us implement a verbosity toggler.

Pitch

Why does this feature belong in the Jest core platform?

Because it can't be implemented from the outside. For obvious reasons, the passed global config is immutable, and the one used by watch() is a local reference that it is the only scope to access.

I'm willing to help with changes in core, and have the two aforementioned plugins at the ready (or almost so, for coverage, as I want to expand it further).

Let me know!

[rogeliog]

I agree! I think it would be great to expand this to a broader set of config options.

We should also explicitly mention in the docs which are the options that can be overridden. We could also add --coverage.

I'm also happy to review the PR

[tdd]

Hey @rogeliog I'm trying to contribute to the codebase, but the current master utterly fails to work for me… Let me elaborate:

• yarn build works fine
• yarn lint (used by yarn test) tells me it can't find the eslint-plugin-jest plugin, which doesn't even exist in ESLin't configuration (either in .eslintrc.js or .vscode/settings.json), so I'm not sure why it needs it. This prevents linting.
• yarn jest fails fast on "Two projects resolved to the same config path", listing the examples/getting_started subdir and Jest's package root dir. Never seen that before.

So I can add code and build, and interactively try it by using npm link or yarn link and playing around with my to-be-published plugins, and I guess I can add to the doc and check the rendering, but I can't lint and run my extra tests.

Any help appreciated 😉

[SimenB]

rm -rf examples && git checkout examples && yarn should fix your second issue at least (lingering node_modules after a rename)

[tdd]

Hey @SimenB thanks for the tip! It worked like a charm. This was indeed not a clean clone, my fork had existed for a long time and had this leftover node_modules.

[SimenB]

the eslint plugin error is probably the same thing - previously that plugin was part of this monorepo. So I'd guess you have a symbolic link in root node_modules pointing to nothing. Just delete it and rerun yarn

[tdd]

I went ahead and did a fresh clone of my fork, fixed the whole shenanigans. Thx!

[github-actions]

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