assertExpectedString(sink.getString());
  }

  public void testRead_toString() throws IOException {
    String string = source.read();
    assertExpectedString(string);
  }

  public void testReadFirstLine() throws IOException {
    if (expectedLines.isEmpty()) {
      assertThat(source.readFirstLine()).isNull();
    } else {
      assertThat(source.readFirstLine()).isEqualTo(expectedLines.get(0));
    }
  }