LibJS: Implement Atomics.compareExchange

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

@@ -0,0 +1,64 @@
+test("invariants", () => {
+    expect(Atomics.compareExchange).toHaveLength(4);
+});
+
+test("error cases", () => {
+    expect(() => {
+        Atomics.compareExchange("not an array", 0, 0, 0);
+    }).toThrow(TypeError);
+
+    expect(() => {
+        const bad_array_type = new Float32Array(4);
+        Atomics.compareExchange(bad_array_type, 0, 0, 0);
+    }).toThrow(TypeError);
+
+    expect(() => {
+        const bad_array_type = new Uint8ClampedArray(4);
+        Atomics.compareExchange(bad_array_type, 0, 0, 0);
+    }).toThrow(TypeError);
+
+    expect(() => {
+        const array = new Int32Array(4);
+        Atomics.compareExchange(array, 100, 0, 0);
+    }).toThrow(RangeError);
+});
+
+test("basic functionality (non-BigInt)", () => {
+    [Int8Array, Int16Array, Int32Array, Uint8Array, Uint16Array, Uint32Array].forEach(ArrayType => {
+        const array = new ArrayType(2);
+        array[0] = 1;
+        array[1] = 2;
+
+        expect(Atomics.compareExchange(array, 0, 0, 5)).toBe(1);
+        expect(array).toEqual([1, 2]);
+
+        expect(Atomics.compareExchange(array, 0, 1, "5")).toBe(1);
+        expect(array).toEqual([5, 2]);
+
+        expect(Atomics.compareExchange(array, 0, "5", 6)).toBe(5);
+        expect(array).toEqual([6, 2]);
+
+        expect(Atomics.compareExchange(array, 1, 2, 3.14)).toBe(2);
+        expect(array).toEqual([6, 3]);
+    });
+});
+
+test("basic functionality (BigInt)", () => {
+    [BigInt64Array, BigUint64Array].forEach(ArrayType => {
+        const array = new ArrayType(2);
+        array[0] = 1n;
+        array[1] = 2n;
+
+        expect(Atomics.compareExchange(array, 0, 0n, 5n)).toBe(1n);
+        expect(array).toEqual([1n, 2n]);
+
+        expect(Atomics.compareExchange(array, 0, 1n, 5n)).toBe(1n);
+        expect(array).toEqual([5n, 2n]);
+
+        expect(Atomics.compareExchange(array, 0, 5n, 6n)).toBe(5n);
+        expect(array).toEqual([6n, 2n]);
+
+        expect(Atomics.compareExchange(array, 1, 2n, 3n)).toBe(2n);
+        expect(array).toEqual([6n, 3n]);
+    });
+});