assertThat(result).isAbsent();
    return new WeakReference<>(shadowLoader);
  }

  @GwtIncompatible // stringConverter
  public void testStringConverter_convert() {
    Converter<String, TestEnum> converter = Enums.stringConverter(TestEnum.class);
    assertEquals(TestEnum.CHEETO, converter.convert("CHEETO"));
    assertEquals(TestEnum.HONDA, converter.convert("HONDA"));

    }
  }

  @J2ktIncompatible
  @GwtIncompatible // NullPointerTester
  public void testNulls() {
    new NullPointerTester().testAllPublicStaticMethods(Doubles.class);
  }

  public void testStringConverter_convert() {
    Converter<String, Double> converter = Doubles.stringConverter();
    assertThat(converter.convert("1.0")).isEqualTo((Double) 1.0);
    assertThat(converter.convert("0.0")).isEqualTo((Double) 0.0);

  public void testNulls() {
    new NullPointerTester().testAllPublicStaticMethods(Floats.class);
  }

  @GwtIncompatible // Float.toString returns different value in GWT.
  public void testStringConverter_convert() {
    Converter<String, Float> converter = Floats.stringConverter();
    assertThat(converter.convert("1.0")).isEqualTo((Float) 1.0f);
    assertThat(converter.convert("0.0")).isEqualTo((Float) 0.0f);

  }

  @J2ktIncompatible
  @GwtIncompatible // NullPointerTester
  public void testNulls() {
    new NullPointerTester().testAllPublicStaticMethods(Ints.class);
  }

  public void testStringConverter_convert() {
    Converter<String, Integer> converter = Ints.stringConverter();
    assertThat(converter.convert("1")).isEqualTo((Integer) 1);
    assertThat(converter.convert("0")).isEqualTo((Integer) 0);

    }
  }

  @J2ktIncompatible
  @GwtIncompatible // NullPointerTester
  public void testNulls() {
    new NullPointerTester().testAllPublicStaticMethods(Doubles.class);
  }

  public void testStringConverter_convert() {
    Converter<String, Double> converter = Doubles.stringConverter();
    assertThat(converter.convert("1.0")).isEqualTo((Double) 1.0);
    assertThat(converter.convert("0.0")).isEqualTo((Double) 0.0);

  public void testNulls() {
    new NullPointerTester().testAllPublicStaticMethods(Floats.class);
  }

  @GwtIncompatible // Float.toString returns different value in GWT.
  public void testStringConverter_convert() {
    Converter<String, Float> converter = Floats.stringConverter();
    assertThat(converter.convert("1.0")).isEqualTo((Float) 1.0f);
    assertThat(converter.convert("0.0")).isEqualTo((Float) 0.0f);

  }

  @J2ktIncompatible
  @GwtIncompatible // NullPointerTester
  public void testNulls() {
    new NullPointerTester().testAllPublicStaticMethods(Longs.class);
  }

  public void testStringConverter_convert() {
    Converter<String, Long> converter = Longs.stringConverter();
    assertThat(converter.convert("1")).isEqualTo((Long) 1L);
    assertThat(converter.convert("0")).isEqualTo((Long) 0L);