[mrm-task-lint-staged] lint-staged task not suitable for running multiple times on a project

[anshumanb]

lint-staged task appends npx lint-staged to .husky/pre-commit every time it runs which renders it unsuitable for running more than once. To reproduce:

$ mkdir test
$ cd test
$ git init
$ npm init -y
$ npm install -D eslint
$ npx mrm@2 lint-staged
$ cat .husky/pre-commit
#!/bin/sh
. "$(dirname "$0")/_/husky.sh"

npx lint-staged
$ npx mrm@2 lint-staged
$ cat .husky/pre-commit
#!/bin/sh
. "$(dirname "$0")/_/husky.sh"

npx lint-staged
npx lint-staged

Results are the same if I use npx mrm lint-staged instead of npx mrm@2 lint-staged.

My understanding is that mrm is meant to handle configuration upgrades so running npx mrm@2 lint-staged a second time should have resulted in no changes as there is nothing to upgrade.

$ npm ls
test@1.0.0 /tmp/test
├── eslint@7.32.0
├── husky@7.0.2
└── lint-staged@11.1.2

$ npm --version
7.22.0
$ node --version
v14.17.0

[anshumanb]

In my preset I added a workaround, which may/may not be suitable for the lint-staged task itself:

const lintStaged = require('mrm-task-lint-staged');
const { lines } = require('mrm-core');

const task = () => {
    // For every run of lint-staged, it appends "npx lint-staged" to pre-commit.
    // This needs to happen only once and on subsequent runs the file should
    // remain untouched
    const preCommit = lines('.husky/pre-commit');
    if (preCommit.exists()) {
        preCommit.remove('npx lint-staged').save();
    }

    lintStaged({
    ...

Happy to submit a PR with the above (or similar) if it's suitable.