@Test
void testSplit_StringChar() {

    assertNull(StringUtils.split(null, '.'));
    assertEquals(0, StringUtils.split("", '.').length);
    String str = "a.b.. c";
    String[] res = StringUtils.split(str, '.');
    assertEquals(3, res.length);
    assertEquals("a", res[0]);
    assertEquals("b", res[1]);
    assertEquals(" c", res[2]);
    str = ".a.";
    res = StringUtils.split(str, '.');
    assertEquals(1, res.length);
    assertEquals("a", res[0]);
    str = "a b c";
    res = StringUtils.split(str, ' ');
    assertEquals(3, res.length);
    assertEquals("a", res[0]);
    assertEquals("b", res[1]);
    assertEquals("c", res[2]);
}