1 files changed, 63 insertions, 0 deletions
diff --git a/js/src/tests/test262/built-ins/Array/length/define-own-prop-length-coercion-order.js b/js/src/tests/test262/built-ins/Array/length/define-own-prop-length-coercion-order.js
new file mode 100644
index 0000000000..8c0f7a97a8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Array/length/define-own-prop-length-coercion-order.js
@@ -0,0 +1,63 @@
+// Copyright (C) 2020 Alexey Shvayka. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+author: André Bargull
+esid: sec-arraysetlength
+description: >
+  [[Value]] is coerced to number before descriptor validation.
+info: |
+  ArraySetLength ( A, Desc )
+
+  [...]
+  3. Let newLen be ? ToUint32(Desc.[[Value]]).
+  4. Let numberLen be ? ToNumber(Desc.[[Value]]).
+  [...]
+  7. Let oldLenDesc be OrdinaryGetOwnProperty(A, "length").
+  [...]
+  11. If newLen ≥ oldLen, then
+    a. Return OrdinaryDefineOwnProperty(A, "length", newLenDesc).
+
+  OrdinaryDefineOwnProperty ( O, P, Desc )
+
+  [...]
+  3. Return ValidateAndApplyPropertyDescriptor(O, P, extensible, Desc, current).
+
+  ValidateAndApplyPropertyDescriptor ( O, P, extensible, Desc, current )
+
+  [...]
+  7. Else if IsDataDescriptor(current) and IsDataDescriptor(Desc) are both true, then
+    a. If current.[[Configurable]] is false and current.[[Writable]] is false, then
+      i. If Desc.[[Writable]] is present and Desc.[[Writable]] is true, return false.
+features: [Reflect]
+---*/
+
+var array = [1, 2];
+var valueOfCalls = 0;
+var length = {
+  valueOf: function() {
+    valueOfCalls += 1;
+    if (valueOfCalls !== 1) {
+      // skip first coercion at step 3
+      Object.defineProperty(array, "length", {writable: false});
+    }
+    return array.length;
+  },
+};
+
+assert.throws(TypeError, function() {
+  Object.defineProperty(array, "length", {value: length, writable: true});
+}, 'Object.defineProperty(array, "length", {value: length, writable: true}) throws a TypeError exception');
+assert.sameValue(valueOfCalls, 2, 'The value of valueOfCalls is expected to be 2');
+
+
+array = [1, 2];
+valueOfCalls = 0;
+
+assert(
+  !Reflect.defineProperty(array, "length", {value: length, writable: true}),
+  'The value of !Reflect.defineProperty(array, "length", {value: length, writable: true}) is expected to be true'
+);
+assert.sameValue(valueOfCalls, 2, 'The value of valueOfCalls is expected to be 2');
+
+reportCompare(0, 0);