Default value for expand can be 'help' (#457)

* Default value for expand can be 'help'

* Make help the default option if no default key is provided

* tiny change requested by SBoudrias

* simplifying even more :)

* using `choices.realLength`

README.md

@@ -198,7 +198,7 @@ default must the choice `index` in the array)
 #### Expand - `{type: 'expand'}`
 
 Take `type`, `name`, `message`, `choices`[, `default`] properties. (Note that
-default must be the choice `index` in the array)
+default must be the choice `index` in the array. If `default` key not provided, then `help` will be used as default choice)
 
 Note that the `choices` object will take an extra parameter called `key` for the `expand` prompt. This parameter must be a single (lowercased) character. The `h` option is added by the prompt and shouldn't be defined by the user.
 

lib/prompts/expand.js

@@ -222,7 +222,7 @@ Prompt.prototype.validateChoices = function (choices) {
  * @return {String} The rendered choices key string
  */
 Prompt.prototype.generateChoicesString = function (choices, defaultIndex) {
-  var defIndex = 0;
+  var defIndex = choices.realLength - 1;
   if (_.isNumber(defaultIndex) && this.opt.choices.getChoice(defaultIndex)) {
     defIndex = defaultIndex;
   }

test/specs/prompts/expand.js

@@ -44,14 +44,6 @@ describe('`expand` prompt', function () {
     expect(mkPrompt).to.throw(/Reserved key error/);
   });
 
-  it('should take the first choice by default', function (done) {
-    this.expand.run().then(function (answer) {
-      expect(answer).to.equal('acab');
-      done();
-    });
-    this.rl.emit('line');
-  });
-
   it('should allow false as a value', function () {
     var promise = this.expand.run();
 
@@ -133,6 +125,14 @@ describe('`expand` prompt', function () {
     expect(this.rl.output.__raw__).to.contain('(aBcdh)');
   });
 
+  it('should display and capitalize the default choice H (Help) `key` if none provided', function () {
+    delete this.fixture.default;
+    this.expand = new Expand(this.fixture, this.rl);
+    this.expand.run();
+
+    expect(this.rl.output.__raw__).to.contain('(abcdH)');
+  });
+
   it('should \'autocomplete\' the user input', function (done) {
     this.expand = new Expand(this.fixture, this.rl);
     this.expand.run();