assertThat(lowerCase).isNotSameInstanceAs(base16());
    assertThat(lowerCase).isSameInstanceAs(base16().lowerCase());
    testEncodingWithCasing(lowerCase, "foobar", "666f6f626172");
  }

  public void testBase16IgnoreCase() {
    BaseEncoding ignoreCase = base16().ignoreCase();
    assertThat(ignoreCase).isNotSameInstanceAs(base16());

  }

  @Test
  public void testRemoveEqualKeyWithDifferentReference() {
    String fooReference1 = new String("foo");
    String fooReference2 = new String("foo");
    assertThat(fooReference1).isNotSameInstanceAs(fooReference2);

    assertThat(mapCache.put(fooReference1, "bar")).isNull();
    assertThat(mapCache.get(fooReference1)).isEqualTo("bar"); // ensure first reference is cached

  }

  public void testImpliedFeatures_returnsNewSetInstance() {
    Set<Feature<?>> features = newHashSet(IMPLIES_FOO);
    assertThat(impliedFeatures(features)).isNotSameInstanceAs(features);
  }

  public void testImpliedFeatures_returnsImpliedFeatures() {
    assertThat(impliedFeatures(newHashSet(FOO))).isEmpty();

    // fail and will need to be rewritten.

    Class<?> frqC = FinalizableReferenceQueue.class;
    Class<?> sepFrqC = sepLoader.loadClass(frqC.getName());
    assertThat(frqC).isNotSameInstanceAs(sepFrqC);
    // Check the assumptions above.

    // FRQ tries to load the Finalizer class (for the reference-collecting thread) in a few ways.

  }

  public void testImpliedFeatures_returnsNewSetInstance() {
    Set<Feature<?>> features = newHashSet(IMPLIES_FOO);
    assertThat(impliedFeatures(features)).isNotSameInstanceAs(features);
  }

  public void testImpliedFeatures_returnsImpliedFeatures() {
    assertThat(impliedFeatures(newHashSet(FOO))).isEmpty();

    assertDoesntActuallyTrim(iia2);
  }

  private static void assertActuallyTrims(ImmutableDoubleArray iia) {
    ImmutableDoubleArray trimmed = iia.trimmed();
    assertThat(trimmed).isNotSameInstanceAs(iia);

    // Yes, this is apparently how you check array equality in Truth
    assertThat(trimmed.toArray()).isEqualTo(iia.toArray());
  }

    assertThat(Bytes.concat(EMPTY)).isEqualTo(EMPTY);
    assertThat(Bytes.concat(EMPTY, EMPTY, EMPTY)).isEqualTo(EMPTY);
    assertThat(Bytes.concat(ARRAY1)).isEqualTo(ARRAY1);
    assertThat(Bytes.concat(ARRAY1)).isNotSameInstanceAs(ARRAY1);
    assertThat(Bytes.concat(EMPTY, ARRAY1, EMPTY)).isEqualTo(ARRAY1);
    assertThat(Bytes.concat(ARRAY1, ARRAY1, ARRAY1))
        .isEqualTo(new byte[] {(byte) 1, (byte) 1, (byte) 1});

    assertDoesntActuallyTrim(iia2);
  }

  private static void assertActuallyTrims(ImmutableLongArray iia) {
    ImmutableLongArray trimmed = iia.trimmed();
    assertThat(trimmed).isNotSameInstanceAs(iia);

    // Yes, this is apparently how you check array equality in Truth
    assertThat(trimmed.toArray()).isEqualTo(iia.toArray());
  }

    assertDoesntActuallyTrim(iia2);
  }

  private static void assertActuallyTrims(ImmutableLongArray iia) {
    ImmutableLongArray trimmed = iia.trimmed();
    assertThat(trimmed).isNotSameInstanceAs(iia);

    // Yes, this is apparently how you check array equality in Truth
    assertThat(trimmed.toArray()).isEqualTo(iia.toArray());
  }

    assertThat(Booleans.concat(EMPTY, EMPTY, EMPTY)).isEqualTo(EMPTY);
    assertThat(Booleans.concat(ARRAY_FALSE)).isEqualTo(ARRAY_FALSE);
    assertThat(Booleans.concat(ARRAY_FALSE)).isNotSameInstanceAs(ARRAY_FALSE);
    assertThat(Booleans.concat(EMPTY, ARRAY_FALSE, EMPTY)).isEqualTo(ARRAY_FALSE);
    assertThat(Booleans.concat(ARRAY_FALSE, ARRAY_FALSE, ARRAY_FALSE))
        .isEqualTo(new boolean[] {false, false, false});