fix: flatten-duplicate-arrays:false for more than 2 arrays (#128)

Author: laggingreflex

index.js

@@ -639,7 +639,7 @@ function parse (args, opts) {
       o[key] = increment(o[key])
     } else if (Array.isArray(o[key])) {
       if (duplicate && isTypeArray && isValueArray) {
-        o[key] = configuration['flatten-duplicate-arrays'] ? o[key].concat(value) : [o[key]].concat([value])
+        o[key] = configuration['flatten-duplicate-arrays'] ? o[key].concat(value) : (Array.isArray(o[key][0]) ? o[key] : [o[key]]).concat([value])
       } else if (!duplicate && Boolean(isTypeArray) === Boolean(isValueArray)) {
         o[key] = value
       } else {

test/yargs-parser.js

@@ -2088,6 +2088,16 @@ describe('yargs-parser', function () {
 
         parsed['x'].should.deep.equal([['a', 'b'], ['c', 'd']])
       })
+      it('nests duplicate array types of more than 2', function () {
+        var parsed = parser('-x a b -x c d -x e f -x g h', {
+          array: ['x'],
+          configuration: {
+            'flatten-duplicate-arrays': false
+          }
+        })
+
+        parsed['x'].should.deep.equal([['a', 'b'], ['c', 'd'], ['e', 'f'], ['g', 'h']])
+      })
       it('doesn\'t nests single arrays', function () {
         var parsed = parser('-x a b', {
           array: ['x'],