LibJS: Move tests to /Tests/LibJS

Author: https://github.com/gmta
Commit: https://github.com/LadybirdBrowser/ladybird/commit/e3faa9b5add
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/7572
Reviewed-by: https://github.com/trflynn89 ✅

Tests/LibJS/Runtime/builtins/Array/array-spread.js

@@ -0,0 +1,45 @@
+describe("errors", () => {
+    test("cannot spread number in array", () => {
+        expect(() => {
+            [...1];
+        }).toThrowWithMessage(TypeError, "1 is not iterable");
+    });
+
+    test("cannot spread object in array", () => {
+        expect(() => {
+            [...{}];
+        }).toThrowWithMessage(TypeError, "[object Object] is not iterable");
+    });
+});
+
+test("basic functionality", () => {
+    expect([1, ...[2, 3], 4]).toEqual([1, 2, 3, 4]);
+
+    let a = [2, 3];
+    expect([1, ...a, 4]).toEqual([1, 2, 3, 4]);
+
+    let obj = { a: [2, 3] };
+    expect([1, ...obj.a, 4]).toEqual([1, 2, 3, 4]);
+
+    expect([...[], ...[...[1, 2, 3]], 4]).toEqual([1, 2, 3, 4]);
+});
+
+test("allows assignment expressions", () => {
+    expect("([ ...a = { hello: 'world' } ])").toEval();
+    expect("([ ...a += 'hello' ])").toEval();
+    expect("([ ...a -= 'hello' ])").toEval();
+    expect("([ ...a **= 'hello' ])").toEval();
+    expect("([ ...a *= 'hello' ])").toEval();
+    expect("([ ...a /= 'hello' ])").toEval();
+    expect("([ ...a %= 'hello' ])").toEval();
+    expect("([ ...a <<= 'hello' ])").toEval();
+    expect("([ ...a >>= 'hello' ])").toEval();
+    expect("([ ...a >>>= 'hello' ])").toEval();
+    expect("([ ...a &= 'hello' ])").toEval();
+    expect("([ ...a ^= 'hello' ])").toEval();
+    expect("([ ...a |= 'hello' ])").toEval();
+    expect("([ ...a &&= 'hello' ])").toEval();
+    expect("([ ...a ||= 'hello' ])").toEval();
+    expect("([ ...a ??= 'hello' ])").toEval();
+    expect("function* test() { return ([ ...yield a ]); }").toEval();
+});