I’m using date-fns, a JavaScript date utility library. I’m trying to write a Vitest for fromUnixTime.

My Vitest keeps failing:

    describe("fromUnixTime function", () => {
    test("should return the correct date from a Unix timestamp in UK time", () => {
        const unixTimestamp = 1612345678 // Unix timestamp 2021-02-03 04:56:18 UTC

        // Convert Unix timestamp to Date object
        const date = fromUnixTime(unixTimestamp)

        // Verify if the Unix timestamp obtained from the date object matches the original Unix timestamp
        expect(getUnixTime(date)).toBe(unixTimestamp)

        // Verify the components of the date object
        expect(date.getFullYear()).toBe(2021)
        expect(date.getMonth()).toBe(1) // Note: Month is zero-based index
        expect(date.getDate()).toBe(3)
        expect(date.getHours()).toBe(4) // The Unix timestamp is in UTC, so it should be adjusted for UK time zone
        expect(date.getMinutes()).toBe(56)
        expect(date.getSeconds()).toBe(18)
    })
})

In the terminal I see:

 FAIL  src/utils/dates.test.tsx > fromUnixTime function > should return the correct date from a Unix timestamp in UK time
AssertionError: expected 9 to be 4 // Object.is equality

 - Expected
 - Received

 - 4
 - 9


 expect(date.getHours()).toBe(4)