BufferedReaderBuilder { public BufferedReaderBuilder append(String string) { stringBuilder.append(string); return this; } private  BufferedReaderBuilder(); static BufferedReaderBuilder create(); BufferedReaderBuilder append(String string); BufferedReaderBuilder appendLine(String string); BufferedReader build();  }
@Test void testAppend() throws IOException { String actualString = bufferedReaderBuilder .append(firstTestString) .append(secondTestString) .append(thirdTestString) .build().readLine(); Assertions.assertEquals(expectedStringsWithoutNewLine, actualString); }