/**
  * Asserts the start point and the end point of <code>wall</code> are at (<code>xStart</code>,
  * <code>yStart</code>), (<code>xEnd</code>, <code>yEnd</code>).
  */
 private void assertCoordinatesEqualWallPoints(
     float xStart, float yStart, float xEnd, float yEnd, Wall wall) {
   assertTrue(
       "Incorrect X start " + xStart + " " + wall.getXStart(),
       Math.abs(xStart - wall.getXStart()) < 1E-10);
   assertTrue(
       "Incorrect Y start " + yStart + " " + wall.getYStart(),
       Math.abs(yStart - wall.getYStart()) < 1E-10);
   assertTrue(
       "Incorrect X end " + xEnd + " " + wall.getXEnd(), Math.abs(xEnd - wall.getXEnd()) < 1E-10);
   assertTrue(
       "Incorrect Y end " + yEnd + " " + wall.getYEnd(), Math.abs(yEnd - wall.getYEnd()) < 1E-10);
 }