fix: 'undefined' should be taken to mean no argument was provided (#1015)

Author: edmBernard

lib/validation.js

@@ -57,7 +57,7 @@ module.exports = function validation (yargs, usage, y18n) {
   // make sure that any args that require an
   // value (--foo=bar), have a value.
   self.missingArgumentValue = function missingArgumentValue (argv) {
-    const defaultValues = [true, false, '']
+    const defaultValues = [true, false, '', undefined]
     const options = yargs.getOptions()
 
     if (options.requiresArg.length > 0) {

test/validation.js

@@ -369,6 +369,46 @@ describe('validation tests', () => {
         .argv
     })
 
+    it('fails when a required argument of type number is missing', (done) => {
+      yargs('-w')
+        .option('w', {type: 'number', requiresArg: true})
+        .fail((msg) => {
+          msg.should.equal('Missing argument value: w')
+          return done()
+        })
+        .argv
+    })
+
+    it('fails when a required argument of type string is missing', (done) => {
+      yargs('-w')
+        .option('w', {type: 'string', requiresArg: true})
+        .fail((msg) => {
+          msg.should.equal('Missing argument value: w')
+          return done()
+        })
+        .argv
+    })
+
+    it('fails when a required argument of type boolean is missing', (done) => {
+      yargs('-w')
+        .option('w', {type: 'boolean', requiresArg: true})
+        .fail((msg) => {
+          msg.should.equal('Missing argument value: w')
+          return done()
+        })
+        .argv
+    })
+
+    it('fails when a required argument of type array is missing', (done) => {
+      yargs('-w')
+        .option('w', {type: 'array', requiresArg: true})
+        .fail((msg) => {
+          msg.should.equal('Missing argument value: w')
+          return done()
+        })
+        .argv
+    })
+
     it('fails when required arguments are present, but a command is missing', (done) => {
       yargs('-w 10 -m wombat')
         .demand(1, ['w', 'm'])