@Test
    void testNegativeSize() {
        FileSizeFormat format = new FileSizeFormat();
        assertThrows(IllegalArgumentException.class, () -> format.format(-100L));
    }

    static Stream<Arguments> sizeTestData() {
        return Stream.of(
                Arguments.of(0L, "0 B"),
                Arguments.of(5L, "5 B"),
                Arguments.of(10L, "10 B"),
                Arguments.of(15L, "15 B"),