copyOfWrappedSet = ImmutableSet.copyOf(wrappedSet);
    setToTest =
        InvalidatableSet.of(wrappedSet, () -> wrappedSet.contains(1), () -> 1 + "is not present");
  }

  @Test
  @SuppressWarnings("TruthSelfEquals")
  public void testEquals() {
    // sanity check on construction of copyOfWrappedSet
    assertThat(wrappedSet).isEqualTo(copyOfWrappedSet);

    // test that setToTest is still valid