### Question:
FaceValue { @Override public String toString() { String result = ""; for (int line = 0; line < 3; line ++) { result += getLine(line); } return result; } FaceValue(Elements fill); private  FaceValue(); @Override String toString(); Line getLine(int line); Line getRow(int row); void updateLine(int line, Line data); void updateRow(int row, Line data); void rotateClockwise(); Elements get(Neighbor neighborFace); boolean isSolved();  }### Answer:
@Test public void testInvertLine() { assertEquals("OGY", new Line("YGO").invert().toString()); }