michael@0: 
michael@0: var x = Array(4);
michael@0: x[0] = 1;
michael@0: x[1] = 2;
michael@0: x[2] = 3;
michael@0: var y = x.concat();
michael@0: assertEq(y[3], undefined);
michael@0: 
michael@0: var z = x.concat(/abc/).pop();
michael@0: assertEq(z.source, "abc");