LibJS: Implement Temporal.Calendar.prototype.monthDayFromFields()

Userland/Libraries/LibJS/Tests/builtins/Temporal/Calendar/Calendar.prototype.monthDayFromFields.js

@@ -0,0 +1,60 @@
+describe("correct behavior", () => {
+    test("length is 2", () => {
+        expect(Temporal.Calendar.prototype.monthDayFromFields).toHaveLength(2);
+    });
+
+    test("basic functionality", () => {
+        const calendar = new Temporal.Calendar("iso8601");
+        const plainMonthDay = calendar.monthDayFromFields({ year: 2021, month: 7, day: 6 });
+        expect(plainMonthDay.calendar).toBe(calendar);
+        expect(plainMonthDay.monthCode).toBe("M07");
+        expect(plainMonthDay.day).toBe(6);
+
+        const fields = plainMonthDay.getISOFields();
+        expect(fields.isoYear).toBe(1972); // No, this isn't a mistake
+    });
+
+    test("with monthCode", () => {
+        const calendar = new Temporal.Calendar("iso8601");
+        const plainMonthDay = calendar.monthDayFromFields({ monthCode: "M07", day: 6 });
+        expect(plainMonthDay.calendar).toBe(calendar);
+        expect(plainMonthDay.monthCode).toBe("M07");
+        expect(plainMonthDay.day).toBe(6);
+
+        const fields = plainMonthDay.getISOFields();
+        expect(fields.isoYear).toBe(1972);
+    });
+});
+
+describe("errors", () => {
+    test("first argument must be an object", () => {
+        const calendar = new Temporal.Calendar("iso8601");
+        expect(() => {
+            calendar.monthDayFromFields(42);
+        }).toThrowWithMessage(TypeError, "42 is not an object");
+    });
+
+    test("month or monthCode field is required", () => {
+        const calendar = new Temporal.Calendar("iso8601");
+        expect(() => {
+            calendar.monthDayFromFields({ year: 2021 });
+        }).toThrowWithMessage(TypeError, "Required property month is missing or undefined");
+    });
+
+    test("day field is required", () => {
+        const calendar = new Temporal.Calendar("iso8601");
+        expect(() => {
+            calendar.monthDayFromFields({ year: 2021, month: 7 });
+        }).toThrowWithMessage(TypeError, "Required property day is missing or undefined");
+    });
+
+    test("monthCode or year field is required when month is given", () => {
+        const calendar = new Temporal.Calendar("iso8601");
+        expect(() => {
+            calendar.monthDayFromFields({ month: 7, day: 6 });
+        }).toThrowWithMessage(
+            TypeError,
+            "Required property monthCode or year is missing or undefined"
+        );
+    });
+});