fix(core): docusaurus CLI should detect the correct yarn version when suggesting upgrades

[0420syj]

Pre-flight checklist

• I have read the Contributing Guidelines on pull requests.
• If this is a code change: I have written unit tests and/or added dogfooding pages to fully verify the new behavior.
• If this is a new API or substantial change: the PR has an accompanying issue (closes #0000) and the maintainers have approved on my working plan.

Motivation

I've checked PR #8908.
Great idea to check which Yarn verison is being used.

However, the presence of a .yarnrc.yml file alone is not a definitive indicator of Yarn 2+ being used, as this file can be used by Yarn 1.x as well.

Check out the capture image below

This can be happened when you change Yarn 2+ -> Yarn 1

yarn set version 1

So, I think we should check yarnPath value (by using js-yaml),
to make sure what Yarn version is being used.

Test Plan

• Check out an older docusaurus project and copy the file in place.
• Install the project with npm
• Run a npm run start
• Close and run it again
  • Confirm the notice had an appropriate npm i command
• rm -rf node_modules
• Install with yarn classic
• Run yarn start
• Close and run it again
  • Confirm the notice had an appropriate npm i command
• rm -rf node_modules
• Repeat with yarn 2

Test links

Deploy preview: https://deploy-preview-9006--docusaurus-2.netlify.app/

Related issues/PRs

Related PR : #8908

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[slorber]

That looks a bit complicated to me 🤪

What about:

import shell from 'shelljs';

async function getYarnVersion() {
  const fallbackYarnVersion = 1;
  const yarnVersionResult = shell.exec("yarn --version");
  if (yarnVersionResult.code === 0) {
    const majorVersion = parseInt(yarnVersionResult.stdout.split(".")[0]);
    if ( typeof majorVersion === "number" && !Number.isNaN(majorVersion) ) {
      return majorVersion;
    }
  }
  if (await fs.pathExists(path.resolve('yarn.lock'))) {
    return fallbackYarnVersion;
  }
  return undefined;
}

And then usage:

    const getUpgradeCommand = async () => {
      const yarnVersion = await getYarnVersion();
      if (!yarnVersion) {
        return `npm i ${siteDocusaurusPackagesForUpdate}`;
      }
      return yarnVersion === 1
        ? `yarn upgrade ${siteDocusaurusPackagesForUpdate}`
        : `yarn up ${siteDocusaurusPackagesForUpdate}`;
    };

[0420syj]

That looks a bit complicated to me 🤪

What about:

import shell from 'shelljs';

async function getYarnVersion() {
  const fallbackYarnVersion = 1;
  const yarnVersionResult = shell.exec("yarn --version");
  if (yarnVersionResult.code === 0) {
    const majorVersion = parseInt(yarnVersionResult.stdout.split(".")[0]);
    if ( typeof majorVersion === "number" && !Number.isNaN(majorVersion) ) {
      return majorVersion;
    }
  }
  if (await fs.pathExists(path.resolve('yarn.lock'))) {
    return fallbackYarnVersion;
  }
  return undefined;
}

And then usage:

    const getUpgradeCommand = async () => {
      const yarnVersion = await getYarnVersion();
      if (!yarnVersion) {
        return `npm i ${siteDocusaurusPackagesForUpdate}`;
      }
      return yarnVersion === 1
        ? `yarn upgrade ${siteDocusaurusPackagesForUpdate}`
        : `yarn up ${siteDocusaurusPackagesForUpdate}`;
    };

Actually, my first idea was more close to this one🤣
But I was wary of letting it run shell commands.

If there are no security concerns, I fully agree with this improvement.
Not only is it more clear, but I think it's more concise.

[0420syj]

I made a new commit based on the review !

[slorber]

LGTM thanks 👍