Libraries: Move to Userland/Libraries/

Userland/Libraries/LibJS/Tests/builtins/Proxy/Proxy.handler-apply.js

@@ -0,0 +1,36 @@
+describe("[[Call]] trap normal behavior", () => {
+    test("forwarding when not defined in handler", () => {
+        let p = new Proxy(() => 5, { apply: null });
+        expect(p()).toBe(5);
+        p = new Proxy(() => 5, { apply: undefined });
+        expect(p()).toBe(5);
+        p = new Proxy(() => 5, {});
+        expect(p()).toBe(5);
+    });
+
+    test("correct arguments supplied to trap", () => {
+        const f = (a, b) => a + b;
+        const handler = {
+            apply(target, this_, arguments) {
+                expect(target).toBe(f);
+                expect(this_).toBe(handler);
+                if (arguments[2]) return arguments[0] * arguments[1];
+                return f(...arguments);
+            },
+        };
+        p = new Proxy(f, handler);
+
+        expect(p(2, 4)).toBe(6);
+        expect(p(2, 4, true)).toBe(8);
+    });
+});
+
+describe("[[Call]] invariants", () => {
+    test("target must have a [[Call]] slot", () => {
+        [{}, [], new Proxy({}, {})].forEach(item => {
+            expect(() => {
+                new Proxy(item, {})();
+            }).toThrowWithMessage(TypeError, "[object ProxyObject] is not a function");
+        });
+    });
+});