feat(plugins): add getLastRelease hook

The code to determine the last-release is now in its own repository: https://github.com/semantic-release/last-release-npm
One can overwrite that behavior by defining a "getLastRelease" plugin. This way
one can decouple semantic-release from npm, e.g. by implementing a git-tag
based version. This is already worked on: https://github.com/semantic-release/last-release-git-tag

Closes #56

package.json

@@ -24,12 +24,12 @@
     "@semantic-release/commit-analyzer": "^2.0.0",
     "@semantic-release/condition-travis": "^4.0.0",
     "@semantic-release/error": "^1.0.0",
+    "@semantic-release/last-release-npm": "^1.1.1",
     "@semantic-release/release-notes-generator": "^2.0.0",
     "git-head": "^1.2.1",
     "github": "^0.2.4",
     "lodash": "^3.9.3",
     "nopt": "^3.0.3",
-    "npm-registry-client": "^6.4.0",
     "npmconf": "^2.1.2",
     "npmlog": "^1.2.1",
     "parse-github-repo-url": "^1.0.0",

src/lib/last-release.js

@@ -1,26 +0,0 @@
-const SemanticReleaseError = require('@semantic-release/error')
-
-const npmlog = require('npmlog')
-const RegClient = require('npm-registry-client')
-
-module.exports = function ({pkg, npm}, cb) {
-  npmlog.level = npm.loglevel || 'error'
-  const client = new RegClient({log: npmlog})
-
-  client.get(`${npm.registry}${pkg.name.replace('/', '%2F')}`, {
-    auth: npm.auth
-  }, (err, data) => {
-    if (err && err.statusCode === 404) return cb(null, {})
-    if (err) return cb(err)
-
-    const version = data['dist-tags'][npm.tag]
-
-    if (!version) return cb(new SemanticReleaseError(`There is no release with the dist-tag "${npm.tag}" yet. Tag a version first.`, 'ENODISTTAG'))
-
-    cb(null, {
-      version,
-      gitHead: data.versions[version].gitHead,
-      tag: npm.tag
-    })
-  })
-}

src/lib/plugins.js

@@ -5,7 +5,8 @@ let exports = module.exports = function (options) {
     analyzeCommits: exports.normalize(options.analyzeCommits, '@semantic-release/commit-analyzer'),
     generateNotes: exports.normalize(options.generateNotes, '@semantic-release/release-notes-generator'),
     verifyConditions: exports.normalize(options.verifyConditions, '@semantic-release/condition-travis'),
-    verifyRelease: exports.normalize(options.verifyRelease, './plugin-noop')
+    verifyRelease: exports.normalize(options.verifyRelease, './plugin-noop'),
+    getLastRelease: exports.normalize(options.getLastRelease, '@semantic-release/last-release-npm')
   }
 }
 

src/pre.js

@@ -2,14 +2,14 @@ const _ = require('lodash')
 const auto = require('run-auto')
 const semver = require('semver')
 
-const getLastRelease = require('./lib/last-release')
 const getCommits = require('./lib/commits')
 const getType = require('./lib/type')
 
 module.exports = function (config, cb) {
   const { plugins } = config
+
   auto({
-    lastRelease: getLastRelease.bind(null, config),
+    lastRelease: plugins.getLastRelease.bind(null, config),
     commits: ['lastRelease', (cb, results) => {
       getCommits(_.assign({
         lastRelease: results.lastRelease

test/specs/last-release.js

@@ -1,79 +0,0 @@
-const { defaults } = require('lodash')
-const test = require('tap').test
-
-require('../mocks/registry')
-const lastRelease = require('../../dist/lib/last-release')
-
-const npm = {
-  registry: 'http://registry.npmjs.org/',
-  tag: 'latest'
-}
-
-test('last release from registry', (t) => {
-  t.plan(5)
-
-  t.test('get release from package name', (tt) => {
-    lastRelease({
-      pkg: {name: 'available'},
-      npm
-    }, (err, release) => {
-      tt.error(err)
-      tt.is(release.version, '1.33.7', 'version')
-      tt.is(release.gitHead, 'HEAD', 'gitHead')
-      tt.is(release.tag, 'latest', 'dist-tag')
-
-      tt.end()
-    })
-  })
-
-  t.test('get release from a tagged package\'s name', (tt) => {
-    lastRelease({
-      pkg: {name: 'tagged'},
-      npm: defaults({tag: 'foo'}, npm)
-    }, (err, release) => {
-      tt.error(err)
-      tt.is(release.version, '0.8.15', 'version')
-      tt.is(release.gitHead, 'bar', 'gitHead')
-      tt.is(release.tag, 'foo', 'dist-tag')
-
-      tt.end()
-    })
-  })
-
-  t.test('get error from an untagged package\'s name', (tt) => {
-    lastRelease({
-      pkg: {name: 'untagged'},
-      npm: defaults({tag: 'bar'}, npm)
-    }, (err) => {
-      tt.is(err.code, 'ENODISTTAG', 'error')
-
-      tt.end()
-    })
-  })
-
-  t.test('get release from scoped package name', (tt) => {
-    lastRelease({
-      pkg: {name: '@scoped/available'},
-      npm
-    }, (err, release) => {
-      tt.error(err)
-      tt.is(release.version, '1.33.7', 'version')
-      tt.is(release.gitHead, 'HEAD', 'gitHead')
-      tt.is(release.tag, 'latest', 'dist-tag')
-
-      tt.end()
-    })
-  })
-
-  t.test('get nothing from not yet published package name', (tt) => {
-    lastRelease({
-      pkg: {name: 'unavailable'},
-      npm
-    }, (err, release) => {
-      tt.error(err)
-      tt.is(release.version, undefined, 'no version')
-
-      tt.end()
-    })
-  })
-})

test/specs/pre.js

@@ -6,9 +6,16 @@ const pre = proxyquire('../../dist/pre', {
   'child_process': require('../mocks/child-process')
 })
 
+const versions = {
+  available: '1.0.0'
+}
+
 const plugins = {
   verifyRelease: (release, cb) => cb(null, release),
-  analyzeCommits: (commits, cb) => cb(null, 'major')
+  analyzeCommits: (commits, cb) => cb(null, 'major'),
+  getLastRelease: ({ pkg }, cb) => {
+    cb(null, { version: versions[pkg.name] || null, gitHead: 'HEAD' })
+  }
 }
 
 const npm = {