assertThrows(IOException.class, () -> failSource.copyTo(new TestCharSink()));
    assertTrue(failSource.wasStreamClosed());
  }

  public void testClosesOnErrors_copyingToWriterThatThrows() {
    TestCharSource okSource = new TestCharSource(STRING);
    assertThrows(IOException.class, () -> okSource.copyTo(new TestWriter(WRITE_THROWS)));
    assertTrue(okSource.wasStreamClosed());
  }