LibJS: Add all of the WeakSet.prototype methods (add, delete, has)

Userland/Libraries/LibJS/Tests/builtins/WeakSet/WeakSet.prototype.add.js

@@ -0,0 +1,16 @@
+test("basic functionality", () => {
+    expect(WeakSet.prototype.add).toHaveLength(1);
+
+    const weakSet = new WeakSet([{ a: 1 }, { a: 2 }, { a: 3 }]);
+    expect(weakSet.add({ a: 4 })).toBe(weakSet);
+    expect(weakSet.add({ a: 1 })).toBe(weakSet);
+});
+
+test("invalid values", () => {
+    const weakSet = new WeakSet();
+    [-100, Infinity, NaN, "hello", 152n].forEach(value => {
+        expect(() => {
+            weakSet.add(value);
+        }).toThrowWithMessage(TypeError, "is not an object");
+    });
+});

Userland/Libraries/LibJS/Tests/builtins/WeakSet/WeakSet.prototype.delete.js

@@ -0,0 +1,9 @@
+test("basic functionality", () => {
+    expect(WeakSet.prototype.delete).toHaveLength(1);
+
+    var original = [{ a: 1 }, { a: 2 }, { a: 3 }];
+    const weakSet = new WeakSet(original);
+    expect(weakSet.delete(original[0])).toBeTrue();
+    expect(weakSet.delete(original[0])).toBeFalse();
+    expect(weakSet.delete(null)).toBeFalse();
+});

Userland/Libraries/LibJS/Tests/builtins/WeakSet/WeakSet.prototype.has.js

@@ -0,0 +1,12 @@
+test("length is 1", () => {
+    expect(WeakSet.prototype.has).toHaveLength(1);
+});
+
+test("basic functionality", () => {
+    var original = [{ a: 1 }, { a: 2 }, { a: 3 }];
+    var weakSet = new WeakSet(original);
+
+    expect(new WeakSet().has()).toBeFalse();
+    expect(weakSet.has(original[0])).toBeTrue();
+    expect(weakSet.has({ a: 1 })).toBeFalse();
+});