Make prompts when support function.

lib/ask.js

@@ -32,11 +32,9 @@ module.exports = function ask (prompts, data, done) {
  */
 
 function prompt (data, key, prompt, done) {
-  // skip prompts whose when condition is not met
-  if (prompt.when && !evaluate(prompt.when, data)) {
+  if (prompt.when && !(typeof prompt.when === 'function' ? prompt.when(data) : evaluate(prompt.when, data))) {
     return done()
   }
-
   var promptDefault = prompt.default
   if (typeof prompt.default === 'function') {
     promptDefault = function () {

test/e2e/mock-metadata-repo-js/meta.js

@@ -12,6 +12,19 @@ module.exports = {
       validate: function (input) {
         return input === 'custom' ? 'can not input `custom`' : true
       }
+    },
+    q1: {
+      type: 'list',
+      required: true,
+      label: 'Which choice?',
+      choices: ['a1', 'a2']
+    },
+    q2: {
+      when: function (answers) {
+        return answers.q1 === 'a1'
+      },
+      label: 'Which choice',
+      type: 'confirm'
     }
   },
   helpers: {

test/e2e/test.js

@@ -11,6 +11,7 @@ const extend = Object.assign || require('util')._extend
 const generate = require('../../lib/generate')
 const metadata = require('../../lib/options')
 const { isLocalPath, getTemplatePath } = require('../../lib/local-path')
+const ask = require('../../lib/ask')
 
 const MOCK_META_JSON_PATH = path.resolve('./test/e2e/mock-meta-json')
 const MOCK_TEMPLATE_REPO_PATH = path.resolve('./test/e2e/mock-template-repo')
@@ -225,7 +226,23 @@ describe('vue-cli', () => {
     expect(getTemplatePath('../template')).to.equal(path.join(__dirname, '/../../../template'))
   })
 
-  it.only('points out the file in the error', done => {
+  it('"when" set function', () => {
+    var meta = require(path.join(MOCK_METADATA_REPO_JS_PATH, 'meta.js'))
+
+    var collectQa1 = extend({}, answers, { q1: 'a1', q2: 'aq2' })
+    monkeyPatchInquirer(collectQa1)
+    var data = {}
+    ask(meta.prompts, data, function () {
+      expect(data).to.have.property('q2')
+    })
+    var data2 = {}
+    var collectQa2 = extend({}, answers, { q1: 'a2', q2: 'aq2' })
+    monkeyPatchInquirer(collectQa2)
+    ask(meta.prompts, data2, function () {
+      expect(data2).to.not.have.property('q2')
+    })
+  })
+  it('points out the file in the error', done => {
     monkeyPatchInquirer(answers)
     generate('test', MOCK_ERROR, MOCK_TEMPLATE_BUILD_PATH, err => {
       expect(err.message).to.match(/^\[readme\.md\] Parse error/)