[Feature]: Jest-Cli exports some util APIs

[adamma1024]

🚀 Feature Proposal

Proposal: jest-cli package export buildArgv API and init API, or adding callback/plugin system.

https://github.com/facebook/jest/blob/356b3b05b77f927b49e151302edbef6594d09a22/packages/jest-cli/src/cli/index.ts#L51-L86

https://github.com/facebook/jest/blob/34308ae21827a44916471106b4e3afdb3779cbb1/packages/jest-cli/src/init/index.ts#L40-L155

Motivation

My purpose is to do something else when invoke run API of jest-cli, like this:

async function run (maybeArgv, ...) {
  const argv = buildArgv(maybeArgv);

  if (argv.init) {
      await init();
      return;
  }

 // do something
}

As we can see, if I want to let it to work well, I should import buildArgv API and init API from jest-cli/build/cli/index and jest-cli/build/init
After v27, I noticed that jest-cli did not export them anymore. I'm so agreed that it's a great idea to just export APIs which were introduced in the document. But how can I solve this problem in an easy way? I think that I can only rewrite a jest-cli to finish it.
Which sounds so stupid.
So, can jest-cli support this workaround by exporting some util APIs, or adding a callback/plugin system?

Example

By exports in package.json ( the easiest way I think ):

  "exports": {
    ".": {
      "types": "./build/index.d.ts",
      "default": "./build/index.js"
    },
    "./package.json": "./package.json",
    "./bin/jest": "./bin/jest.js",
    "./util": "blabla"     // add this line
  },

By plugin system/ callback:

export async function run(
  maybeArgv?: Array<string>,
  project?: string,
  callback?: any, // add a callback
): Promise<void> {
  try {
    const argv = await buildArgv(maybeArgv);

    if (argv.init) {
      await init();
      return;
    }

    // use callback if it exists.
    if(callback) {
        callback(argv, project);
    } else {
        const projects = getProjectListFromCLIArgs(argv, project);

        const {results, globalConfig} = await runCLI(argv, projects);
        readResultsAndExit(results, globalConfig);
    }
  } catch (error: any) {
    clearLine(process.stderr);
    clearLine(process.stdout);
    if (error?.stack) {
      console.error(chalk.red(error.stack));
    } else {
      console.error(chalk.red(error));
    }

    exit(1);
    throw error;
  }
}

Pitch

The most important point is that I think jest really need a plugin system( or callback ) to ensure users can do something else easier.
The second point is a little "selfish" because jest doing that is really easier than me, lol. Otherwise, I must rewrite jest-cli in my project to do that.

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[SimenB]

@adamma1024 sorry, missed this. You're basically wanting #5048. However, we can export those APIs you imported from build if you want. Wanna send a PR?

[github-actions]

This issue is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 30 days.

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