k -> {
                  throw new AssertionFailedError();
                }));
    expectUnchanged();
  }

  @MapFeature.Require(SUPPORTS_PUT)
  public void testComputeIfAbsent_functionReturnsNullNotInserted() {
    assertNull(
        "computeIfAbsent(absent, returnsNull) should return null",
        getMap()
            .computeIfAbsent(
                k3(),
                k -> {