Set<String> unfiltered = Sets.newLinkedHashSet();
                unfiltered.add("yyy");
                Collections.addAll(unfiltered, elements);
                unfiltered.add("zzz");
                return Sets.filter(unfiltered, Collections2Test.NOT_YYY_ZZZ);
              }
            })
        .named("Sets.filter")
        .withFeatures(

        Settings s = Settings.newInstance();

        s = s.withLocalRepository("xxx");
        assertEquals("xxx", s.getLocalRepository());

        s = s.withLocalRepository("yyy");
        assertEquals("yyy", s.getLocalRepository());

        s = s.withLocalRepository(null);
        assertNull(s.getLocalRepository());
    }

                Set<String> unfiltered = Sets.newLinkedHashSet();
                unfiltered.add("yyy");
                Collections.addAll(unfiltered, elements);
                unfiltered.add("zzz");
                return Sets.filter(unfiltered, Collections2Test.NOT_YYY_ZZZ);
              }
            })
        .named("Sets.filter")
        .withFeatures(

        systemHelper.addDesignJspFileName("xxx", "yyy");
        assertEquals("yyy", systemHelper.getDesignJspFileName("xxx"));
        final Pair<String, String>[] designJspFileNames = systemHelper.getDesignJspFileNames();
        assertEquals(1, designJspFileNames.length);
        assertEquals("xxx", designJspFileNames[0].getFirst());
        assertEquals("yyy", designJspFileNames[0].getSecond());
    }

    Map<String, Integer> filtered = Maps.filterKeys(unfiltered, NOT_LENGTH_3);
    filtered.put("a", 1);
    filtered.put("b", 2);
    assertEquals(ImmutableMap.of("a", 1, "b", 2), filtered);

    try {
      filtered.put("yyy", 3);
      fail();
    } catch (IllegalArgumentException expected) {
    }
  }

  public void testFilteredKeysIllegalPutAll() {
    Map<String, Integer> unfiltered = createUnfiltered();

    Map<String, Integer> filtered = Maps.filterKeys(unfiltered, NOT_LENGTH_3);
    filtered.put("a", 1);
    filtered.put("b", 2);
    assertEquals(ImmutableMap.of("a", 1, "b", 2), filtered);

    try {
      filtered.put("yyy", 3);
      fail();
    } catch (IllegalArgumentException expected) {
    }
  }

  public void testFilteredKeysIllegalPutAll() {
    Map<String, Integer> unfiltered = createUnfiltered();