public static String toString(String[] line, boolean quote) {
        return toString(line, quote, " ");
    }
@Test
    void testToStringWithSeparator() {
        final String separator = "], [";
        assertEquals("", CommandLine.toString(null, false, separator));

        assertEquals(ARG_SPACES_NOQUOTES,
                CommandLine.toString(new String[]{ARG_SPACES_NOQUOTES}, false, separator));

        assertEquals(ARG_SPACES_NOQUOTES + separator + ARG_NOSPACES,
                CommandLine.toString(new String[]{ARG_SPACES_NOQUOTES, ARG_NOSPACES}, false, separator));

        assertEquals(String.join(separator, ARG_SPACES_NOQUOTES, ARG_NOSPACES, ARG_SPACES),
                CommandLine.toString(new String[]{ARG_SPACES_NOQUOTES, ARG_NOSPACES, ARG_SPACES},
                        false, separator));
    }