LibJS: Implement Temporal.PlainYearMonth.prototype.since()

Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainYearMonth/PlainYearMonth.prototype.since.js

@@ -0,0 +1,120 @@
+describe("correct behavior", () => {
+    test("length is 1", () => {
+        expect(Temporal.PlainYearMonth.prototype.since).toHaveLength(1);
+    });
+
+    test("basic functionality", () => {
+        const values = [
+            [[0, 1], [0, 1], "PT0S"],
+            [[2, 3], [1, 2], "P1Y1M"],
+            [[1, 2], [0, 1], "P1Y1M"],
+            [[0, 1], [1, 2], "-P1Y1M"],
+            [[0, 12], [0, 1], "P11M"],
+            [[0, 1], [0, 12], "-P11M"],
+        ];
+        for (const [args, argsOther, expected] of values) {
+            const plainYearMonth = new Temporal.PlainYearMonth(...args);
+            const other = new Temporal.PlainYearMonth(...argsOther);
+            expect(plainYearMonth.since(other).toString()).toBe(expected);
+        }
+    });
+
+    test("smallestUnit option", () => {
+        const plainYearMonth = new Temporal.PlainYearMonth(1, 2);
+        const other = new Temporal.PlainYearMonth(0, 1);
+        const values = [
+            ["year", "P1Y"],
+            ["month", "P1Y1M"],
+        ];
+        for (const [smallestUnit, expected] of values) {
+            expect(plainYearMonth.since(other, { smallestUnit }).toString()).toBe(expected);
+        }
+    });
+
+    test("largestUnit option", () => {
+        const plainYearMonth = new Temporal.PlainYearMonth(1, 2);
+        const other = new Temporal.PlainYearMonth(0, 1);
+        const values = [
+            ["year", "P1Y1M"],
+            ["month", "P13M"],
+        ];
+        for (const [largestUnit, expected] of values) {
+            expect(plainYearMonth.since(other, { largestUnit }).toString()).toBe(expected);
+        }
+    });
+});
+
+describe("errors", () => {
+    test("this value must be a Temporal.PlainYearMonth object", () => {
+        expect(() => {
+            Temporal.PlainYearMonth.prototype.since.call("foo", {});
+        }).toThrowWithMessage(TypeError, "Not an object of type Temporal.PlainYearMonth");
+    });
+
+    test("disallowed smallestUnit option values", () => {
+        const values = [
+            "week",
+            "day",
+            "hour",
+            "minute",
+            "second",
+            "millisecond",
+            "microsecond",
+            "nanosecond",
+        ];
+        for (const smallestUnit of values) {
+            const plainYearMonth = new Temporal.PlainYearMonth(1970, 1);
+            const other = new Temporal.PlainYearMonth(1970, 1);
+            expect(() => {
+                plainYearMonth.since(other, { smallestUnit });
+            }).toThrowWithMessage(
+                RangeError,
+                `${smallestUnit} is not a valid value for option smallestUnit`
+            );
+        }
+    });
+
+    test("disallowed largestUnit option values", () => {
+        const values = [
+            "week",
+            "day",
+            "hour",
+            "minute",
+            "second",
+            "millisecond",
+            "microsecond",
+            "nanosecond",
+        ];
+        for (const largestUnit of values) {
+            const plainYearMonth = new Temporal.PlainYearMonth(1970, 1);
+            const other = new Temporal.PlainYearMonth(1970, 1);
+            expect(() => {
+                plainYearMonth.since(other, { largestUnit });
+            }).toThrowWithMessage(
+                RangeError,
+                `${largestUnit} is not a valid value for option largestUnit`
+            );
+        }
+    });
+
+    test("cannot compare dates from different calendars", () => {
+        const calendarOne = {
+            toString() {
+                return "calendarOne";
+            },
+        };
+
+        const calendarTwo = {
+            toString() {
+                return "calendarTwo";
+            },
+        };
+
+        const plainYearMonthOne = new Temporal.PlainYearMonth(1970, 1, calendarOne);
+        const plainYearMonthTwo = new Temporal.PlainYearMonth(1970, 1, calendarTwo);
+
+        expect(() => {
+            plainYearMonthOne.since(plainYearMonthTwo);
+        }).toThrowWithMessage(RangeError, "Cannot compare dates from two different calendars");
+    });
+});