serenity/Userland/Libraries/LibJS/Tests/builtins/Temporal/TimeZone/TimeZone.from.js

describe("normal behavior", () => {
    test("length is 1", () => {
        expect(Temporal.TimeZone.from).toHaveLength(1);
    });

    test("basic functionality", () => {
        // From object
        const timeZone = new Temporal.TimeZone("UTC");
        const timeZoneLike = {};
        const zonedDateTimeLike = { timeZone: {} };
        expect(Temporal.TimeZone.from(timeZone)).toBe(timeZone);
        expect(Temporal.TimeZone.from(timeZoneLike)).toBe(timeZoneLike);
        expect(Temporal.TimeZone.from(zonedDateTimeLike)).toBe(zonedDateTimeLike.timeZone);

        // From string
        const values = [
            ["UTC", "UTC"],
            ["GMT", "UTC"],
            ["Etc/UTC", "UTC"],
            ["Etc/GMT", "UTC"],
            ["Etc/GMT0", "UTC"], // IANA legacy name
            ["Etc/GMT+0", "UTC"], // IANA legacy name
            ["Etc/GMT-0", "UTC"], // IANA legacy name
            ["Etc/GMT+6", "Etc/GMT+6"],
            ["Etc/GMT-6", "Etc/GMT-6"],
            ["Etc/GMT+12", "Etc/GMT+12"],
            ["Etc/GMT-12", "Etc/GMT-12"],
            ["Europe/London", "Europe/London"],
            ["Europe/Isle_of_Man", "Europe/London"],
            ["1970-01-01+01", "+01:00"],
            ["1970-01-01+01[-12:34]", "-12:34"],
            ["1970-01-01T00:00:00+01", "+01:00"],
            ["1970-01-01T00:00:00.000000000+01", "+01:00"],
            ["1970-01-01T00:00:00.000000000+01:00:00", "+01:00"],
            ["1970-01-01+12:34", "+12:34"],
            ["1970-01-01+12:34:56", "+12:34:56"],
            ["1970-01-01+12:34:56.789", "+12:34:56.789"],
            ["1970-01-01+12:34:56.789[-01:00]", "-01:00"],
            ["1970-01-01-12:34", "-12:34"],
            ["1970-01-01-12:34:56", "-12:34:56"],
            ["1970-01-01-12:34:56.789", "-12:34:56.789"],
            ["1970-01-01-12:34:56.789[+01:00]", "+01:00"],
        ];
        for (const [arg, expected] of values) {
            expect(Temporal.TimeZone.from(arg).id).toBe(expected);
        }
    });

    test("ToTemporalTimeZone fast path returns if it is passed a Temporal.TimeZone instance", () => {
        // This is obseravble via there being no property lookups (avoiding a "timeZone" property lookup in this case)
        let madeObservableHasPropertyLookup = false;
        class TimeZone extends Temporal.TimeZone {
            constructor() {
                super("UTC");
            }

            get timeZone() {
                madeObservableHasPropertyLookup = true;
                return this;
            }
        }
        const timeZone = new TimeZone();
        Temporal.TimeZone.from(timeZone);
        expect(madeObservableHasPropertyLookup).toBeFalse();
    });
});