chore: reconfigure ESLint build, improve lint speed #4078

adidahiya · 2020-04-21T06:11:37Z

Rename @blueprintjs/eslint-plugin-blueprint to @blueprintjs/eslint-plugin for brevity. The last part of the name was redundant, and ESLint will resolve the package correctly without it. This required changing some inline enable/disable code flags.
Remove a config option (createDefaultProgram) added in Fix failure to run eslint on win platform #4060 which was greatly slowing down ESLint. We don't need to create a default program for each file encountered; we can be explicit about what is in the TS program.
Be more explicit about ESLint's working directories
Remove tslint-plugin-prettier from @blueprintjs/tslint-config
Install eslint-plugin-prettier in @blueprintjs/eslint-config
- Avoid running eslint-plugin-prettier in CI, but continue to run it in the default case so that vscode-eslint can report & fix errors for eslint and prettier in a single pass (we do this because vscode doesn't run multiple formatters for a filetype, and it is cumbersome to explicitly have to run both formatters while coding).

During this process I did some very rough profiling of different lint configurations on my Macbook. This is for linting the whole monorepo with lerna run lint:es --parallel:

Lint task	Type info?	Run prettier?	createDefaultProgram: true	Time (s)
tslint	no	no		8
eslint (w/ eslint-plugin-tslint)	no	no	no	8
eslint	typescript-eslint	no	no	21
eslint (w/ eslint-plugin-tslint)	typescript-eslint	no	no	26.7
eslint + tslint	typescript-eslint	no	no	31
tslint	ts	no		32
eslint (w/ eslint-plugin-tslint)	typescript-eslint	eslint-plugin-prettier	no	42.7
eslint (w/ eslint-plugin-tslint)	typescript-eslint	eslint-plugin-prettier	yes	72
eslint + tslint	typescript-eslint	eslint-plugin-prettier	yes	78

From these performance characteristics I decided that:

running TSLint rules through ESLint with eslint-plugin-tslint does not cause a significant performance impact, so we should continue doing it
running prettier through ESLint has a moderate impact, so we should avoid doing it when possible and use the typescript-eslint team's advice of creating a yarn format command to run prettier. in cases where convenience outweighs the performance cost (vscode-eslint), we should continue to run eslint-plugin-prettier.

There are a bunch of whitespace formatting changes in this PR (you can view the diff without them here). Some of them are in .md files which were never formatted before, others are in test/ folders where tslint hadn't been running properly before. Outside of those files I'm not 100% sure why there are code diffs on line break formatting. I've kept the prettier version the same in this PR; the next one will include the bump to v2.0.

blueprint-bot · 2020-04-21T06:53:52Z