fail();
    } catch (NullPointerException expected) {
    }

    assertEquals("a:00;00:b", j.useForNull("00").join(mapWithNulls));

    StringBuilder sb = new StringBuilder();
    j.appendTo(sb, ImmutableMap.of(1, 2, 3, 4, 5, 6));
    assertEquals("1:2;3:4;5:6", sb.toString());
  }

  public void testEntries() {
    MapJoiner j = Joiner.on(";").withKeyValueSeparator(":");

      fail();
    } catch (NullPointerException expected) {
    }

    assertEquals("a:00;00:b", j.useForNull("00").join(mapWithNulls));

    StringBuilder sb = new StringBuilder();
    j.appendTo(sb, ImmutableMap.of(1, 2, 3, 4, 5, 6));
    assertEquals("1:2;3:4;5:6", sb.toString());
  }

  public void testEntries() {
    MapJoiner j = Joiner.on(";").withKeyValueSeparator(":");