testBytes(2, EXPECTED_TWO_BYTE_ROUNDTRIPPABLE_COUNT);
  }

  /** Tests that round tripping of all three byte permutations work. */
  @GwtIncompatible // java.nio.charset.Charset

  public void testIsWellFormed_3Bytes() {
    testBytes(3, EXPECTED_THREE_BYTE_ROUNDTRIPPABLE_COUNT);
  }

  /**
   * Tests that round tripping of a sample of four byte permutations work. All permutations are