JUnit testing Game code -beginner

[Tate Hsumsor]

Hi guys

I'm new to unit testing and I'm completely stuck on testing these 2 methods in a game class. I've been looking on-line for simple JUnit instructions for beginners and I haven't really found anything usefull, I would appreciate some recommendations as well. I was reading somewhere about mockito and I've downloaded it but still have no clear idea of how to implement. I'm just getting really frustrated. Thanks in advance.

@Override
    public Play makePlay(Table table) throws CantPlayException {
    
    	// displays left and right of the table
        System.out.println("Left of table is " + table.left());
        System.out.println("Right of table is " + table.right());
        Play p = null;
        
        // while it is valid play the game continues else throws CantPlayException
        boolean isNum = true;
        while(isNum){
            displayWhatisInHand();
            System.out.print("Enter the bone you wish to "
            		+ "play or enter 0 to pick up a bone from the "
            		+ "boneyard and pass the game to the other player.\nEnter 100 to end the game: ");
         try{
            int pick = getInputNumber();
             isNum = false;
             
             // when the player has no bones or pass the game to the other player
             if(pick == 0){
                 throw new CantPlayException();
             }
             
             //when the player want to finish the game
             if(pick == 100){
            	 for(int i = 0; i <= 6; i++){
            		if(i == table.left()){
            			 Bone s = new Bone(i,i);
            			 p = new Play(s, Play.LEFT); 
            		 }
            	 }
             } 
             else{
                Bone b = inHand.remove(pick - 1);
                	// check if picked bone can be played
                    if (b.right() == table.left()|| (b.left() == table.left())||b.left() == table.right()||b.right() == table.right()){
                        
                    	// check if the bone at hand matches either right of left of the table
                        if((b.right() == table.right() || b.right() == table.left())
                        &&(b.left() == table.right() || b.left() == table.left())
                        && b.left() != b.right()){
                                boolean rL;
                                
                                	// if the bone at hand can play either side of the table prompt user to choose
                                    do{
                                       rL = false;
                                    int side = playRightOrLeft();
                                    if(side == 0){
                                        if (b.right() == table.left()|| (b.left() == table.left())){
                                            p = new Play(b, Play.LEFT);
                                        }
                                   }
                                   else if(side == 1){
                                        if (b.left() == table.right()||(b.right() == table.right())){
                                            p = new Play(b, Play.RIGHT);
                                        }
                                    }
                                    else{
                                        System.out.println("Invalid entry. Please try again!");
                                        rL = true;
                                    }
                                }while(rL);
                        }
                        else{
                        	// if only one side of the bone at hand matches that of the table 
                             if (b.left() == table.right()||(b.right() == table.right())){
                                            p = new Play(b, Play.RIGHT);
                              }
                             else if (b.right() == table.left()|| (b.left() == table.left())){
                                            p = new Play(b, Play.LEFT);
                                        }
                        }
               }
               else{
            	  // invalid play  
                 System.out.println("\n");
            	   p = new Play(b, Play.LEFT);
                }
            } 
        }
         // invalid input caught with IllegalArgumentExcpetion 
        catch (IllegalArgumentException e){
            System.out.println(e.getMessage());
          isNum = true;
        }
     } 
        return p;
    }

Method. 2

 /**
     * adds bone back to the player's hand 
     * 
     * @param  bone that is the bone played incorrectly by the player
     */
    @Override
    public void takeBack(Bone bone) {
        inHand.add(bone);
    }

[Jeanne Boyarsky]

I can’t tell what method 2 does. It looks like inHand is a collection? If so, you would test by calling it. Then you’d call another method that gets the inHand collection so you can assert the size is one larger or that it contains the bone object.

Method 1 could use some refactoring. It is really complicated which makes it hard to read and maintain. It has a complexity of at least 19. (# of conditionals and loops). 10 is considered high and many people (myself included) consider 10 to be too high. Consider extracting some of that logic to helper methods.

That said, when writing tests for a complex method that you don’t want to refactor (or don’t yet understand), you start simply. Can you write a test for the case where the input number (pick) is 0? You need to find the right input and have your test check an exception is thrown.