concat test, make sure to slice arguments in array.concat

haileys · Jan 10, 2012 · 3f67eae · 3f67eae
1 parent 205d325
commit 3f67eae
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diff --git a/lib/twostroke/runtime/lib/array.js b/lib/twostroke/runtime/lib/array.js
@@ -26,7 +26,7 @@ Array.prototype.concat = function() {
 	Array.prototype.slice.call(this).forEach(function(el) {
 		x.push(el);
 	});
-	arguments.forEach(function(obj) {
+	Array.prototype.slice.call(arguments).forEach(function(obj) {
 	  if(obj instanceof Array) {
 	    obj.forEach(function(el) {
 	      x.push(el);

diff --git a/test/array.js b/test/array.js
@@ -52,4 +52,20 @@ test("length=", function() {
   var a = [1,2,3,4,5,6,7];
   a.length = 4;
   assert("1,2,3,4" == a);
+});
+
+test("concat", function() {
+  var a = [];
+
+  assert(a.concat(1,2,3) == "1,2,3");
+  assert(a == "", "concat mutated array");
+
+  assert(a.concat([1,2,3],4,[5]) == "1,2,3,4,5");
+  assert(a == "", "concat mutated array");
+
+  var b = [1,2,3];
+  assert(b.concat() == "1,2,3");
+  assert(b.concat() !== b);
+
+  assert(Array.prototype.concat.call({ length: 2, 0: 1, 1: 2 }, [3, 4]) == "1,2,3,4");
 });