Add [[GetPrototypeOf]] tests

test/built-ins/Proxy/getPrototypeOf/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-getprototypeof
+description: >
+  If "getPrototypeOf" trap is null or undefined, [[GetPrototypeOf]] call
+  is properly forwarded to [[ProxyTarget]] (which is also a Proxy object).
+info: |
+  [[GetPrototypeOf]] ( )
+
+  [...]
+  4. Let target be O.[[ProxyTarget]].
+  5. Let trap be ? GetMethod(handler, "getPrototypeOf").
+  6. If trap is undefined, then
+    a. Return ? target.[[GetPrototypeOf]]()
+
+  [[GetPrototypeOf]] ( )
+
+  [...]
+  7. Let handlerProto be ? Call(trap, handler, « target »).
+  [...]
+  13. Return handlerProto.
+features: [Proxy]
+---*/
+
+var targetPrototype = {};
+var target = new Proxy({}, {
+  getPrototypeOf: function(_target) {
+    return targetPrototype;
+  },
+});
+
+var proxy = new Proxy(target, {});
+
+assert.sameValue(Object.getPrototypeOf(proxy), targetPrototype);

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

@@ -0,0 +1,25 @@
+// 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-getprototypeof
+description: >
+  If "getPrototypeOf" trap is null or undefined, [[GetPrototypeOf]] call
+  is properly forwarded to [[ProxyTarget]] (which is also a Proxy object).
+info: |
+  [[GetPrototypeOf]] ( )
+
+  [...]
+  4. Let target be O.[[ProxyTarget]].
+  5. Let trap be ? GetMethod(handler, "getPrototypeOf").
+  6. If trap is undefined, then
+    a. Return ? target.[[GetPrototypeOf]]()
+features: [Proxy]
+---*/
+
+var plainObjectTarget = new Proxy(Object.create(null), {});
+var plainObjectProxy = new Proxy(plainObjectTarget, {
+  getPrototypeOf: null,
+});
+
+assert.sameValue(Object.getPrototypeOf(plainObjectProxy), null);

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

@@ -0,0 +1,25 @@
+// 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-getprototypeof
+description: >
+  If "getPrototypeOf" trap is null or undefined, [[GetPrototypeOf]] call
+  is properly forwarded to [[ProxyTarget]] (which is also a Proxy object).
+info: |
+  [[GetPrototypeOf]] ( )
+
+  [...]
+  4. Let target be O.[[ProxyTarget]].
+  5. Let trap be ? GetMethod(handler, "getPrototypeOf").
+  6. If trap is undefined, then
+    a. Return ? target.[[GetPrototypeOf]]()
+features: [Proxy]
+---*/
+
+var arrayTarget = new Proxy([], {});
+var arrayProxy = new Proxy(arrayTarget, {
+  getPrototypeOf: undefined,
+});
+
+assert.sameValue(Object.getPrototypeOf(arrayProxy), Array.prototype);