LibJS: Implement Temporal.Duration.prototype.toJSON()

Author: https://github.com/linusg
Commit: 90fa356b93
Pull-request: https://github.com/SerenityOS/serenity/pull/10834
Reviewed-by: https://github.com/IdanHo ✅

Userland/Libraries/LibJS/Tests/builtins/Temporal/Duration/Duration.prototype.toJSON.js

@@ -0,0 +1,19 @@
+describe("correct behavior", () => {
+    test("length is 0", () => {
+        expect(Temporal.Duration.prototype.toJSON).toHaveLength(0);
+    });
+
+    test("basic functionality", () => {
+        expect(new Temporal.Duration(1, 2, 3, 4, 5, 6, 7, 8, 9, 10).toJSON()).toBe(
+            "P1Y2M3W4DT5H6M7.00800901S"
+        );
+    });
+});
+
+describe("errors", () => {
+    test("this value must be a Temporal.Duration object", () => {
+        expect(() => {
+            Temporal.Duration.prototype.toJSON.call("foo");
+        }).toThrowWithMessage(TypeError, "Not an object of type Temporal.Duration");
+    });
+});