Coverage: Object.assign, Assignment to readonly property of target must throw a TypeError exception. Fixes gh-2788

test/built-ins/Object/assign/assignment-to-readonly-property-of-target-must-throw-a-typeerror-exception.js

@@ -0,0 +1,29 @@
+// Copyright 2020 Rick Waldron. All rights reserved.
+// This code is governed by the license found in the LICENSE file.
+
+/*---
+esid:  sec-object.assign
+description: >
+  Assignment to readonly property of target must throw a TypeError exception
+info: |
+  Let to be ? ToObject(target).
+  If only one argument was passed, return to.
+  For each element nextSource of sources, do
+    If nextSource is neither undefined nor null, then
+      Let from be ! ToObject(nextSource).
+      Let keys be ? from.[[OwnPropertyKeys]]().
+      For each element nextKey of keys, do
+        Let desc be ? from.[[GetOwnProperty]](nextKey).
+        If desc is not undefined and desc.[[Enumerable]] is true, then
+          Let propValue be ? Get(from, nextKey).
+          Perform ? Set(to, nextKey, propValue, true).
+
+  Set ( O, P, V, Throw ) sec-set-o-p-v-throw
+
+  Let success be ? O.[[Set]](P, V, O).
+  If success is false and Throw is true, throw a TypeError exception.
+---*/
+
+assert.throws(TypeError, () => {
+  Object.assign('a', [1]);
+});