[Fix] ensure utils.merge handles merging two arrays.

lib/utils.js

@@ -1,5 +1,7 @@
 'use strict';
 
+var has = Object.prototype.hasOwnProperty;
+
 var hexTable = (function () {
     var array = [];
     for (var i = 0; i < 256; ++i) {
@@ -10,7 +12,7 @@ var hexTable = (function () {
 }());
 
 exports.arrayToObject = function (source, options) {
-    var obj = options.plainObjects ? Object.create(null) : {};
+    var obj = options && options.plainObjects ? Object.create(null) : {};
     for (var i = 0; i < source.length; ++i) {
         if (typeof source[i] !== 'undefined') {
             obj[i] = source[i];
@@ -46,6 +48,21 @@ exports.merge = function (target, source, options) {
         mergeTarget = exports.arrayToObject(target, options);
     }
 
+    if (Array.isArray(target) && Array.isArray(source)) {
+        source.forEach(function (item, i) {
+            if (has.call(target, i)) {
+                if (target[i] && typeof target[i] === 'object') {
+                    target[i] = exports.merge(target[i], item, options);
+                } else {
+                    target.push(item);
+                }
+            } else {
+                target[i] = item;
+            }
+        });
+        return target;
+    }
+
     return Object.keys(source).reduce(function (acc, key) {
         var value = source[key];
 
@@ -143,10 +160,9 @@ exports.compact = function (obj, references) {
     }
 
     var keys = Object.keys(obj);
-    for (var j = 0; j < keys.length; ++j) {
-        var key = keys[j];
+    keys.forEach(function (key) {
         obj[key] = exports.compact(obj[key], refs);
-    }
+    });
 
     return obj;
 };

test/utils.js

@@ -5,5 +5,18 @@ var utils = require('../lib/utils');
 
 test('merge()', function (t) {
     t.deepEqual(utils.merge({ a: 'b' }, { a: 'c' }), { a: ['b', 'c'] }, 'merges two objects with the same key');
+
+    var oneMerged = utils.merge({ foo: 'bar' }, { foo: { first: '123' } });
+    t.deepEqual(oneMerged, { foo: ['bar', { first: '123' }] }, 'merges a standalone and an object into an array');
+
+    var twoMerged = utils.merge({ foo: ['bar', { first: '123' }] }, { foo: { second: '456' } });
+    t.deepEqual(twoMerged, { foo: { 0: 'bar', 1: { first: '123' }, second: '456' } }, 'merges a standalone and two objects into an array');
+
+    var sandwiched = utils.merge({ foo: ['bar', { first: '123', second: '456' }] }, { foo: 'baz' });
+    t.deepEqual(sandwiched, { foo: ['bar', { first: '123', second: '456' }, 'baz'] }, 'merges an object sandwiched by two standalones into an array');
+
+    var nestedArrays = utils.merge({ foo: ['baz'] }, { foo: ['bar', 'xyzzy'] });
+    t.deepEqual(nestedArrays, { foo: ['baz', 'bar', 'xyzzy'] });
+
     t.end();
 });