changed interface Game to abstract class for better object orientation

src/main/java/Game/Game.java

@@ -1,7 +1,24 @@
 package Game;
 
-public interface Game {
-    public abstract void print();
+import java.util.ArrayList;
+
+public abstract class Game {
+
+    protected ArrayList<String> outputBuffer = new ArrayList<>();
+
+    public void print() {
+        for (String s : outputBuffer) {
+            System.out.println(s);
+        }
+    }
+
+    protected void setOutputBuffer(ArrayList<String> outputBuffer) {
+        this.outputBuffer = outputBuffer;
+    }
+
+    public ArrayList<String> getOutputBuffer() {
+        return this.outputBuffer;
+    }
 
 
 

src/main/java/Game/Tictactoe.java

@@ -2,7 +2,7 @@ package Game;
 
 import java.util.ArrayList;
 
-public class Tictactoe implements Game {
+public class Tictactoe extends Game {
 
 
     enum State {
@@ -10,7 +10,6 @@ public class Tictactoe implements Game {
         CROSS,
         EMPTY
     }
-    private ArrayList<String> outputBuffer = new ArrayList<String>();
     private String input;
     private State[] currentBoard;
 
@@ -22,12 +21,7 @@ public class Tictactoe implements Game {
         currentBoard = newBoard();
     }
 
-    @Override
-    public void print() {
-        for (int i = 0; i < outputBuffer.size(); i++) {
-            System.out.println(outputBuffer.get(i));
-        }
-    }
+
 
     public char getStatedChar(State state) {
         switch (state) {
@@ -50,10 +44,6 @@ public class Tictactoe implements Game {
         return board;
     }
 
-    void setOutputBuffer(ArrayList<String> outputBuffer){
-        this.outputBuffer = outputBuffer;
-    }
-
     public State[] getCurrentBoard() {
         return currentBoard;
     }

src/test/java/Game/GameTest.java

@@ -0,0 +1,43 @@
+package Game;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+import java.util.ArrayList;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.mock;
+
+class GameTest {
+
+    private final ByteArrayOutputStream outContent = new ByteArrayOutputStream();
+    private final PrintStream originalOut = System.out;
+
+    Game game;
+
+    @BeforeEach
+    void setUp() {
+        System.setOut(new PrintStream(outContent));
+        game = mock(Game.class, Mockito.CALLS_REAL_METHODS);
+    }
+
+    @AfterEach
+    void tearDown() {
+        System.setOut(originalOut);
+    }
+
+    @Test
+    public void print() {
+        ArrayList<String> testOB = new ArrayList<>();
+        testOB.add("Hello");
+        testOB.add("World");
+        testOB.add("!!!");
+        game.setOutputBuffer(testOB);
+        game.print();
+        assertEquals("Hello\nWorld\n!!!\n", outContent.toString().replaceAll("\r", ""));
+    }
+}

src/test/java/Game/TictactoeTest.java

@@ -12,35 +12,18 @@ import static org.junit.jupiter.api.Assertions.*;
 
 class TictactoeTest {
 
-    private final ByteArrayOutputStream outContent = new ByteArrayOutputStream();
-    private final PrintStream originalOut = System.out;
-
     Tictactoe ttt;
 
-
     @BeforeEach
     void setUp() {
         ttt = new Tictactoe();
-        System.setOut(new PrintStream(outContent));
     }
 
     @AfterEach
     void tearDown() {
-        System.setOut(originalOut);
-    }
 
-    @Test
-    public void testPrint() {
-        ArrayList<String> testOB = new ArrayList<String>();
-        testOB.add("Hello");
-        testOB.add("World");
-        testOB.add("!!!");
-        ttt.setOutputBuffer(testOB);
-        ttt.print();
-        assertEquals("Hello\nWorld\n!!!\n", outContent.toString().replaceAll("\r", ""));
     }
 
-
     @Test
     void getStatedChar() {
         assertEquals(ttt.getStatedChar(Tictactoe.State.CIRCLE), 'O');