assertThrows(
        IllegalArgumentException.class,
        () -> COMMA_SPLITTER.withKeyValueSeparator("=").split("a=1,c=2="));
  }

  public void testMapSplitter_orderedResults() {
    Map<String, String> m =
        COMMA_SPLITTER.withKeyValueSeparator(":").split("boy:tom,girl:tina,cat:kitty,dog:tommy");

    assertThat(m.keySet()).containsExactly("boy", "girl", "cat", "dog").inOrder();