assertEquals(STRING.length(), source.copyTo(builder));
    assertTrue(source.wasStreamOpened() && source.wasStreamClosed());

    assertThat(builder.toString()).isEqualTo(STRING);
  }

  public void testCopyTo_charSink() throws IOException {
    TestCharSink sink = new TestCharSink();

    assertFalse(sink.wasStreamOpened() || sink.wasStreamClosed());

    assertEquals(STRING.length(), source.copyTo(sink));