fix: requiresArg should only be enforced if argument exists (#1043)

lib/validation.js

@@ -59,13 +59,15 @@ module.exports = function validation (yargs, usage, y18n) {
   self.missingArgumentValue = function missingArgumentValue (argv) {
     const defaultValues = [true, false, '', undefined]
     const options = yargs.getOptions()
-
     if (options.requiresArg.length > 0) {
       const missingRequiredArgs = []
 
       options.requiresArg.forEach((key) => {
-        const value = argv[key]
+        // if the argument is not set in argv no need to check
+        // whether a right-hand-side has been provided.
+        if (!argv.hasOwnProperty(key)) return
 
+        const value = argv[key]
         // if a value is explicitly requested,
         // flag argument as missing if it does not
         // look like foo=bar was entered.

test/validation.js

@@ -419,6 +419,16 @@ describe('validation tests', () => {
         .argv
     })
 
+    // see: https://github.com/yargs/yargs/issues/1041
+    it('does not fail if required argument is not provided', (done) => {
+      yargs('')
+        .option('w', {type: 'array', requiresArg: true})
+        .parse('', (err, argv, output) => {
+          expect(err).to.equal(null)
+          return done()
+        })
+    })
+
     it('fails without a message if msg is null', (done) => {
       yargs([])
         .demand(1, null)