@Test
  public void canExtractTwoSymbolsFromLine() throws Exception {
    String xSymbol = "";
    xSymbol += "xxx\n";
    xSymbol += "xxx\n";
    xSymbol += "xxx\n";

    String ySymbol = "";
    ySymbol += "yyy\n";
    ySymbol += "yyy\n";
    ySymbol += "yyy\n";

    String symbols = "";
    symbols += "xxxyyy\n";
    symbols += "xxxyyy\n";
    symbols += "xxxyyy\n";

    when(symbolReader.nextLine()).thenReturn(symbols);

    List<String> expectedSymbols = new ArrayList<>();
    expectedSymbols.add(xSymbol);
    expectedSymbols.add(ySymbol);

    assertEquals(expectedSymbols, symbolExtractor.extractNextLine());
  }
  @Test
  public void canExtractOneSymbolFromLine() throws Exception {
    String symbol = "";
    symbol += "xxx\n";
    symbol += "xxx\n";
    symbol += "xxx\n";

    when(symbolReader.nextLine()).thenReturn(symbol);

    List<String> expectedSymbols = asList(symbol);
    assertEquals(expectedSymbols, symbolExtractor.extractNextLine());
  }