Check package name availability in custom registry

[itaisteinherz]

Fixes #424 (comment)

[sindresorhus]

@seognil Can you test this?

[seognil]

Thanks for the patch, BUT it still won't work as what issue ticket described.

maybe the process should be like

// Pseudocode here
exports.isPackageNameAvailable = async pkg => {
	const latest = await latestVersion()(pkg.name);
	return latest == undefined // so it is not published
};

(inspired by update-notifier)
(Not dive too deep into it yet, I'm not sure if it works with the private registry, e.g. verdaccio's http://localhost:4873/)
(I'd check that myself later)

---

Test Info

// package.json

{
  "name": "@seognil-playground/npm-feature-test",
  // ...
  "publishConfig": {
    "registry": "https://registry.npmjs.org/",
    "access": "public"
  },
}

# shell

$ np --version 
5.0.3


$ np

Publish a new version of @seognil-playground/npm-feature-test (current: 0.0.12)
# ...
? Select semver increment or specify new version patch  0.0.13
? This scoped repo @seognil-playground/npm-feature-test hasn't been published. Do you want to publish it publicly? (y/N) 

[aladdin-add]

is it going to support custom registry? I've switched to https://npm.taobao.org/ , but 3 tests failed:

 index › version is invalid

  /Users/weiran/repo/work/np/test/index.js:6

   5:   const message = 'Version should be either patch, minor, major, prepatch, preminor, premajor, prerelease, or a valid semver version.';
   6:   await t.throwsAsync(np('foo'), message);                                                                                             
   7:   await t.throwsAsync(np('4.x.3'), message);                                                                                           

  Promise rejected with unexpected exception:

  Error {
    context: {},
    message: 'Connection to npm registry failed',
  }

  Expected message to equal:

  'Version should be either patch, minor, major, prepatch, preminor, premajor, prerelease, or a valid semver version.'



  index › errors on too low version

  /Users/weiran/repo/work/np/test/index.js:21

   20: test('errors on too low version', async t => {                                                                              
   21:   await t.throwsAsync(np('1.0.0'), /New version `1\.0\.0` should be higher than current version `\d+\.\d+\.\d+`/);          
   22:   await t.throwsAsync(np('1.0.0-beta'), /New version `1\.0\.0-beta` should be higher than current version `\d+\.\d+\.\d+`/);

  Promise rejected with unexpected exception:

  Error {
    context: {},
    message: 'Connection to npm registry failed',
  }

  Expected message to match:

  /New version `1\.0\.0` should be higher than current version `\d+\.\d+\.\d+`/



  index › version is pre-release

  /Users/weiran/repo/work/np/test/index.js:12

   11:   const message = 'You must specify a dist-tag using --tag when publishing a pre-release version. This prevents accidentally tagging unstable ver…
   12:   await t.throwsAsync(np('premajor'), message);                                                                                                   
   13:   await t.throwsAsync(np('preminor'), message);                                                                                                   

  Promise rejected with unexpected exception:

  Error {
    context: {},
    message: 'Connection to npm registry failed',
  }

  Expected message to equal:

  'You must specify a dist-tag using --tag when publishing a pre-release version. This prevents accidentally tagging unstable versions as "latest". https://docs.npmjs.com/cli/dist-tag'

npm ERR! Test failed.  See above for more details.

[itaisteinherz]

I think that this, together with #410, will solve #424, so let's put this on hold until #410 gets merged.

[chinesedfan]

As #410 has been "merged"(in fact, 1c9d05f did the work), shall we merge this one?