unshift-nonwritable-length.js (2175B)
1 load(libdir + "asserts.js"); 2 3 function f(arr) 4 { 5 assertEq(arr.unshift(3, 5, 7, 9), 8); // if it doesn't throw :-) 6 } 7 8 var N = 100; 9 10 function test(out) 11 { 12 // Create an array of arrays, to be iterated over for [].unshift-calling. We 13 // can't just loop on unshift on a single array with non-writable length 14 // because unshift throws when called on an array with non-writable length. 15 var arrs = out.arrs = []; 16 for (var i = 0; i < N; i++) 17 arrs.push([0, 1, 2, 3]); 18 19 // Use a much-greater capacity than the eventual non-writable length, just for 20 // variability. 21 var a = [0, 1, 2, 3, 4, 5, 6, 7]; 22 Object.defineProperty(a, "length", { writable: false, value: 4 }); 23 24 arrs.push(a); 25 26 for (var i = 0, sz = arrs.length; i < sz; i++) 27 f(arrs[i]); 28 } 29 30 var obj = {}; 31 assertThrowsInstanceOf(function() { test(obj); }, TypeError); 32 33 var arrs = obj.arrs; 34 assertEq(arrs.length, N + 1); 35 for (var i = 0; i < N; i++) 36 { 37 assertEq(arrs[i].length, 8, "unexpected length for arrs[" + i + "]"); 38 assertEq(arrs[i][0], 3, "bad element for arrs[" + i + "][0]"); 39 assertEq(arrs[i][1], 5, "bad element for arrs[" + i + "][1]"); 40 assertEq(arrs[i][2], 7, "bad element for arrs[" + i + "][2]"); 41 assertEq(arrs[i][3], 9, "bad element for arrs[" + i + "][3]"); 42 assertEq(arrs[i][4], 0, "bad element for arrs[" + i + "][4]"); 43 assertEq(arrs[i][5], 1, "bad element for arrs[" + i + "][5]"); 44 assertEq(arrs[i][6], 2, "bad element for arrs[" + i + "][6]"); 45 assertEq(arrs[i][7], 3, "bad element for arrs[" + i + "][7]"); 46 } 47 48 var a = arrs[N]; 49 assertEq(a[0], 0, "bad element for a[0]"); 50 assertEq(a[1], 1, "bad element for a[1]"); 51 assertEq(a[2], 2, "bad element for a[2]"); 52 assertEq(a[3], 3, "bad element for a[3]"); 53 assertEq(a.hasOwnProperty(4), false, "shouldn't have added any elements"); 54 assertEq(a[4], undefined); 55 assertEq(a.hasOwnProperty(5), false, "shouldn't have added any elements"); 56 assertEq(a[5], undefined); 57 assertEq(a.hasOwnProperty(6), false, "shouldn't have added any elements"); 58 assertEq(a[6], undefined); 59 assertEq(a.hasOwnProperty(7), false, "shouldn't have added any elements"); 60 assertEq(a[7], undefined); 61 assertEq(a.length, 4, "length shouldn't have been changed");