LibJS: Implement Atomics.add

Userland/Libraries/LibJS/Tests/builtins/Atomics/Atomics.add.js

@@ -0,0 +1,60 @@
+test("invariants", () => {
+    expect(Atomics.add).toHaveLength(3);
+});
+
+test("error cases", () => {
+    expect(() => {
+        Atomics.add("not an array", 0, 1);
+    }).toThrow(TypeError);
+
+    expect(() => {
+        const bad_array_type = new Float32Array(4);
+        Atomics.add(bad_array_type, 0, 1);
+    }).toThrow(TypeError);
+
+    expect(() => {
+        const bad_array_type = new Uint8ClampedArray(4);
+        Atomics.add(bad_array_type, 0, 1);
+    }).toThrow(TypeError);
+
+    expect(() => {
+        const array = new Int32Array(4);
+        Atomics.add(array, 100, 1);
+    }).toThrow(RangeError);
+});
+
+test("basic functionality (non-BigInt)", () => {
+    [Int8Array, Int16Array, Int32Array, Uint8Array, Uint16Array, Uint32Array].forEach(ArrayType => {
+        const array = new ArrayType(4);
+
+        expect(Atomics.add(array, 0, 1)).toBe(0);
+        expect(array).toEqual([1, 0, 0, 0]);
+
+        expect(Atomics.add(array, 0, 1)).toBe(1);
+        expect(array).toEqual([2, 0, 0, 0]);
+
+        expect(Atomics.add(array, 2, 3.14)).toBe(0);
+        expect(array).toEqual([2, 0, 3, 0]);
+
+        expect(Atomics.add(array, 3, "1")).toBe(0);
+        expect(array).toEqual([2, 0, 3, 1]);
+    });
+});
+
+test("basic functionality (BigInt)", () => {
+    [BigInt64Array, BigUint64Array].forEach(ArrayType => {
+        const array = new ArrayType(4);
+
+        expect(Atomics.add(array, 0, 1n)).toBe(0n);
+        expect(array).toEqual([1n, 0n, 0n, 0n]);
+
+        expect(Atomics.add(array, 0, 1n)).toBe(1n);
+        expect(array).toEqual([2n, 0n, 0n, 0n]);
+
+        expect(Atomics.add(array, 2, 3n)).toBe(0n);
+        expect(array).toEqual([2n, 0n, 3n, 0n]);
+
+        expect(Atomics.add(array, 3, 4n)).toBe(0n);
+        expect(array).toEqual([2n, 0n, 3n, 4n]);
+    });
+});