Characterization Testing: Hand

We'll continue characterizing and refactoring the display methods in Hand in this lab.

We're Done When...

We know we're done when there are we have removed all System.out.print statements from the Hand class, as well as any "display" methods that return a String.

A. Refactor Hand's Display Face Up Card

First, let's tackle the displayFaceUpCard method.

1. As you did in the previous lab, create a characterization test for Hand.displayFaceUpCard(), like this:

   Start With...

   package com.jitterted.ebp.blackjack;
   
   import org.junit.jupiter.api.Test;
   
   import java.util.List;
   
   import static org.assertj.core.api.Assertions.assertThat;
   
   public class HandDisplayTest {
     @Test
     public void displayFaceUpCard() throws Exception {
       Hand hand = new Hand(List.of(new Card(Suit.HEARTS, Rank.ACE)));
   
       assertThat(hand.displayFaceUpCard())
           .isEqualTo("");
     }
   }
   

2. For the refactor, the transformer (ConsoleCard) will need access to the Face Up card so:

   • Create a public dealerFaceUpCard() query method on Hand that returns the first Card from the list. You can do this via an Extract Method refactoring.

3. Refactor displayFaceUpCard to be a static method, and then move it (via Move Static Method) to a new class named ConsoleHand. Be sure to run the tests!

B. Repeat for Hand's Display

Don't forget to run all tests after each step and make sure that they pass before moving on.

1. Write a characterization test for Hand's display() method. Since it doesn't return anything, you will have to refactor it to split it into two methods:

   • One method that returns a String (named cardsAsString) and

   • Another that does the println of the String.

   Note

   Be sure to add two cards to the Hand for this test to ensure you capture the behavior of a two-card Hand.

2. Create a public cards() query method on Hand that returns a List<Card>.

   Tip

   Since we want to continue to encapsulate Hand's list, be sure to return a copy of the internal collection.

3. Refactor your new cardsAsString method to be static and then use Move Static Method (shortcut key is F6) to move it to ConsoleHand.

4. Get rid of the System.out.println reference in the display() method by inlining it into Game.

C. Complete "Purification" for Hand

Since displayValue() also returns a String that's meant for console output, we need to remove it to complete the purification of the Hand class. You will have to make the tradeoff between hiding the value() method, and purifying the class. Remember that pure domain outweighs the desire for encapsulation.

Once you remove the displayValue() method, and expose the value(), what tests need to be changed? Hint: is valueEquals() still needed?

Note

Make sure all the tests pass.

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You are done!