         }
     }
     
+    func testAllLaddersHaveProperStartAndEnd() {
+        for ladder in board.ladders {
+            let (start, end) = ladder
+            XCTAssertNotEqual(start, end)
+            XCTAssertLessThan(start, end)
+            XCTAssertLessThan(end, 25)
+            XCTAssertGreaterThan(start, 0)
+        }
+    }
+
+    
 }

    
    class Board {
        let size = 25
        let snakes: [(Int,Int)] = [(24, 1), (24, 1), (24, 1), (24, 1)]
        
        var position = 0
        
        
        func move(numberOfFields: Int) {

            let newPosition = position + numberOfFields
            
            if (newPosition < 0) {
                position = 0
            } else if (newPosition > size) {
                position = size
            } else {
                position = newPosition
            }
        }
    }

        XCTAssertEqual(board.position, 25)
    }
    
    func testBoardMoveToSnakesHead() {
      board.move(24)
      XCTAssertEqual(board.position, 1)
    }
    
    func testBoardMoveToLadderStart() {
        board.move(3)
        XCTAssertEqual(board.position, 16)
    }
    
    func testAllSnakesHaveProperHeadAndTailEnd() {
