Add [[SetPrototypeOf]] tests

test/built-ins/Proxy/setPrototypeOf/trap-is-missing-target-is-proxy.js

@@ -0,0 +1,36 @@
+// Copyright (C) 2020 Alexey Shvayka. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-proxy-object-internal-methods-and-internal-slots-setprototypeof-v
+description: >
+  If "setPrototypeOf" trap is null or undefined, [[SetPrototypeOf]] call
+  is properly forwarded to [[ProxyTarget]] (which is also a Proxy object).
+info: |
+  [[SetPrototypeOf]] ( V )
+
+  [...]
+  5. Let target be O.[[ProxyTarget]].
+  6. Let trap be ? GetMethod(handler, "setPrototypeOf").
+  7. If trap is undefined, then
+    a. Return ? target.[[SetPrototypeOf]](V).
+
+  [[SetPrototypeOf]] ( V )
+
+  [...]
+  8. Let booleanTrapResult be ! ToBoolean(? Call(trap, handler, « target, V »)).
+  9. If booleanTrapResult is false, return false.
+features: [Proxy]
+---*/
+
+var target = new Proxy({}, {
+  setPrototypeOf: function(_target, _value) {
+    return false;
+  },
+});
+
+var proxy = new Proxy(target, {});
+
+assert.throws(TypeError, function() {
+  Object.setPrototypeOf(proxy, null);
+});

test/built-ins/Proxy/setPrototypeOf/trap-is-null-target-is-proxy.js

@@ -0,0 +1,40 @@
+// Copyright (C) 2020 Alexey Shvayka. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-proxy-object-internal-methods-and-internal-slots-setprototypeof-v
+description: >
+  If "setPrototypeOf" trap is null or undefined, [[SetPrototypeOf]] call
+  is properly forwarded to [[ProxyTarget]] (which is also a Proxy object).
+info: |
+  [[SetPrototypeOf]] ( V )
+
+  [...]
+  5. Let target be O.[[ProxyTarget]].
+  6. Let trap be ? GetMethod(handler, "setPrototypeOf").
+  7. If trap is undefined, then
+    a. Return ? target.[[SetPrototypeOf]](V).
+
+  OrdinarySetPrototypeOf ( O, V )
+
+  [...]
+  8. Repeat, while done is false,
+    a. If p is null, set done to true.
+    b. Else if SameValue(p, O) is true, return false.
+    [...]
+features: [Proxy]
+---*/
+
+var plainObject = {};
+var plainObjectTarget = new Proxy(plainObject, {});
+var plainObjectProxy = new Proxy(plainObjectTarget, {
+  setPrototypeOf: null,
+});
+
+Object.setPrototypeOf(plainObjectProxy, null);
+assert.sameValue(Object.getPrototypeOf(plainObject), null);
+
+var cyclicPrototype = Object.create(plainObject);
+assert.throws(TypeError, function() {
+  Object.setPrototypeOf(plainObjectProxy, cyclicPrototype);
+});

test/built-ins/Proxy/setPrototypeOf/trap-is-undefined-target-is-proxy.js

@@ -0,0 +1,38 @@
+// Copyright (C) 2020 Alexey Shvayka. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-proxy-object-internal-methods-and-internal-slots-setprototypeof-v
+description: >
+  If "setPrototypeOf" trap is null or undefined, [[SetPrototypeOf]] call
+  is properly forwarded to [[ProxyTarget]] (which is also a Proxy object).
+info: |
+  [[SetPrototypeOf]] ( V )
+
+  [...]
+  5. Let target be O.[[ProxyTarget]].
+  6. Let trap be ? GetMethod(handler, "setPrototypeOf").
+  7. If trap is undefined, then
+    a. Return ? target.[[SetPrototypeOf]](V).
+
+  OrdinarySetPrototypeOf ( O, V )
+
+  [...]
+  4. Let extensible be O.[[Extensible]].
+  5. If extensible is false, return false.
+features: [Proxy]
+---*/
+
+var array = [];
+var arrayTarget = new Proxy(array, {});
+var arrayProxy = new Proxy(arrayTarget, {
+  setPrototypeOf: undefined,
+});
+
+Object.setPrototypeOf(arrayProxy, Number.prototype);
+assert.sameValue(Object.getPrototypeOf(array), Number.prototype);
+
+Object.preventExtensions(array);
+assert.throws(TypeError, function() {
+  Object.setPrototypeOf(arrayProxy, null);
+});