feat: make opts object optional for .option() (yargs#624)

README.md

@@ -1082,8 +1082,8 @@ For example:
 
 ```js
 require('yargs')
-  .option('foobar', {})
-  .option('foobaz', {})
+  .option('foobar')
+  .option('foobaz')
   .completion()
   .getCompletion(['./test.js', '--foo'], function (completions) {
     console.log(completions)
@@ -1310,13 +1310,14 @@ var argv = require('yargs')
   .argv
 ```
 
-.option(key, opt)
+.option(key, [opt])
 -----------------
-.options(key, opt)
+.options(key, [opt])
 ------------------
 
-Instead of chaining together `.alias().demand().default().describe().string()`, you can specify
-keys in `opt` for each of the chainable methods.
+This method can be used to make yargs aware of options that _could_
+exist. You can also pass an `opt` object which can hold further
+customization, like `.alias()`, `.demand()` etc. for that option.
 
 For example:
 

test/yargs.js

@@ -124,6 +124,16 @@ describe('yargs dsl tests', function () {
     })
   })
 
+  it('should not require config object for an option', function () {
+    var r = checkOutput(function () {
+      return yargs([])
+        .option('x')
+        .argv
+    })
+
+    expect(r.errors).to.deep.equal([])
+  })
+
   describe('showHelpOnFail', function () {
     it('should display custom failure message, if string is provided as first argument', function () {
       var r = checkOutput(function () {

yargs.js

@@ -1,4 +1,3 @@
-const assert = require('assert')
 const Command = require('./lib/command')
 const Completion = require('./lib/completion')
 const Parser = require('yargs-parser')
@@ -394,7 +393,9 @@ function Yargs (processArgs, cwd, parentRequire) {
         self.options(k, key[k])
       })
     } else {
-      assert(typeof opt === 'object', 'second argument to option must be an object')
+      if (typeof opt !== 'object') {
+        opt = {}
+      }
 
       options.key[key] = true // track manually set keys.