LibJS: Implement Atomics.exchange

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

@@ -0,0 +1,74 @@
+test("invariants", () => {
+    expect(Atomics.exchange).toHaveLength(3);
+});
+
+test("error cases", () => {
+    expect(() => {
+        Atomics.exchange("not an array", 0, 0);
+    }).toThrow(TypeError);
+
+    expect(() => {
+        const bad_array_type = new Float32Array(4);
+        Atomics.exchange(bad_array_type, 0, 0);
+    }).toThrow(TypeError);
+
+    expect(() => {
+        const bad_array_type = new Uint8ClampedArray(4);
+        Atomics.exchange(bad_array_type, 0, 0);
+    }).toThrow(TypeError);
+
+    expect(() => {
+        const array = new Int32Array(4);
+        Atomics.exchange(array, 100, 0);
+    }).toThrow(RangeError);
+});
+
+test("basic functionality (non-BigInt)", () => {
+    [Int8Array, Int16Array, Int32Array, Uint8Array, Uint16Array, Uint32Array].forEach(ArrayType => {
+        const array = new ArrayType(4);
+        array[0] = 1;
+        array[1] = 2;
+        array[2] = 3;
+        array[3] = 4;
+
+        expect(Atomics.exchange(array, 0, 5)).toBe(1);
+        expect(array).toEqual([5, 2, 3, 4]);
+
+        expect(Atomics.exchange(array, 0, 6)).toBe(5);
+        expect(array).toEqual([6, 2, 3, 4]);
+
+        expect(Atomics.exchange(array, "1", 7)).toBe(2);
+        expect(array).toEqual([6, 7, 3, 4]);
+
+        expect(Atomics.exchange(array, 2, "8")).toBe(3);
+        expect(array).toEqual([6, 7, 8, 4]);
+
+        expect(Atomics.exchange(array, 3.14, 9)).toBe(4);
+        expect(array).toEqual([6, 7, 8, 9]);
+    });
+});
+
+test("basic functionality (BigInt)", () => {
+    [BigInt64Array, BigUint64Array].forEach(ArrayType => {
+        const array = new ArrayType(4);
+        array[0] = 1n;
+        array[1] = 2n;
+        array[2] = 3n;
+        array[3] = 4n;
+
+        expect(Atomics.exchange(array, 0, 5n)).toBe(1n);
+        expect(array).toEqual([5n, 2n, 3n, 4n]);
+
+        expect(Atomics.exchange(array, 0, 6n)).toBe(5n);
+        expect(array).toEqual([6n, 2n, 3n, 4n]);
+
+        expect(Atomics.exchange(array, 1, 7n)).toBe(2n);
+        expect(array).toEqual([6n, 7n, 3n, 4n]);
+
+        expect(Atomics.exchange(array, 2, 8n)).toBe(3n);
+        expect(array).toEqual([6n, 7n, 8n, 4n]);
+
+        expect(Atomics.exchange(array, 3, 9n)).toBe(4n);
+        expect(array).toEqual([6n, 7n, 8n, 9n]);
+    });
+});