feat(plugins): run verifications in series

With this new feature you can pass an array of plugin locations/names to
both "verifyConditions" and "verifyRelease" in your `package.json`'s "release"
field. This will run multiple verification plugins in series.

package.json

@@ -36,6 +36,7 @@
     "parse-github-repo-url": "^1.0.0",
     "require-relative": "^0.8.7",
     "run-auto": "^1.1.2",
+    "run-series": "^1.1.2",
     "semver": "^5.0.1"
   },
   "devDependencies": {

src/lib/plugins.js

@@ -1,13 +1,34 @@
 const relative = require('require-relative')
+const series = require('run-series')
 
 let exports = module.exports = function (options) {
-  return {
+  var plugins = {
     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'),
     getLastRelease: exports.normalize(options.getLastRelease, '@semantic-release/last-release-npm')
   }
+
+  ;['verifyConditions', 'verifyRelease'].forEach((plugin) => {
+    if (!Array.isArray(options[plugin])) {
+      plugins[plugin] = exports.normalize(
+        options[plugin],
+        plugin === 'verifyConditions' ?
+          '@semantic-release/condition-travis' :
+          './plugin-noop'
+      )
+      return
+    }
+
+    plugins[plugin] = function (pluginOptions, cb) {
+      var tasks = options[plugin].map((step) => {
+        return exports.normalize(step, './plugin-noop').bind(null, pluginOptions)
+      })
+
+      series(tasks, cb)
+    }
+  })
+
+  return plugins
 }
 
 exports.normalize = function (pluginConfig, fallback) {

test/mocks/plugin-error-a.js

@@ -0,0 +1,3 @@
+module.exports = function (config, options, cb) {
+  cb(new Error('a'))
+}

test/mocks/plugin-error-b.js

@@ -0,0 +1,3 @@
+module.exports = function (config, options, cb) {
+  cb(new Error('b'))
+}

test/mocks/plugin-result-a.js

@@ -0,0 +1,3 @@
+module.exports = function (config, options, cb) {
+  cb(null, 'a')
+}

test/mocks/plugin-result-b.js

@@ -0,0 +1,3 @@
+module.exports = function (config, options, cb) {
+  cb(null, 'b')
+}

test/specs/plugins.js

@@ -3,7 +3,7 @@ const test = require('tap').test
 const plugins = require('../../dist/lib/plugins')
 
 test('export plugins', (t) => {
-  t.plan(4)
+  t.plan(5)
 
   const defaultPlugins = plugins({})
 
@@ -11,6 +11,59 @@ test('export plugins', (t) => {
   t.is(typeof defaultPlugins.generateNotes, 'function')
   t.is(typeof defaultPlugins.verifyConditions, 'function')
   t.is(typeof defaultPlugins.verifyRelease, 'function')
+  t.is(typeof defaultPlugins.getLastRelease, 'function')
+})
+
+test('plugin pipelines', (t) => {
+  t.plan(3)
+
+  t.test('get all results', (tt) => {
+    const pipelinePlugins = plugins({
+      verifyRelease: [
+        './dist/lib/plugin-noop',
+        './.test/mocks/plugin-result-a',
+        './.test/mocks/plugin-result-b'
+      ]
+    })
+
+    pipelinePlugins.verifyRelease({}, (err, results) => {
+      tt.error(err)
+      tt.same(results, [undefined, 'a', 'b'])
+      tt.end()
+    })
+  })
+
+  t.test('get first error', (tt) => {
+    const pipelinePlugins = plugins({
+      verifyConditions: [
+        './dist/lib/plugin-noop',
+        './.test/mocks/plugin-error-a',
+        './.test/mocks/plugin-error-b'
+      ]
+    })
+
+    pipelinePlugins.verifyConditions({}, (err) => {
+      tt.is(err.message, 'a')
+      tt.end()
+    })
+  })
+
+  t.test('get error and only results before', (tt) => {
+    const pipelinePlugins = plugins({
+      verifyRelease: [
+        './dist/lib/plugin-noop',
+        './.test/mocks/plugin-result-a',
+        './.test/mocks/plugin-error-b',
+        './.test/mocks/plugin-result-b'
+      ]
+    })
+
+    pipelinePlugins.verifyRelease({}, (err, results) => {
+      tt.is(err.message, 'b')
+      tt.same(results, [undefined, 'a', undefined])
+      tt.end()
+    })
+  })
 })
 
 test('normalize and load plugin', (t) => {