tictactoe: added easy AI

src/main/java/de/tims/tictactoe/ai/AIEasy.java

@@ -0,0 +1,28 @@
+package de.tims.tictactoe.ai;
+
+import de.tims.tictactoe.GameLogic;
+
+import java.util.Random;
+
+public class AIEasy implements TicTacToeAI {
+	private static final char AI_CHAR = 'o';
+	
+	private Random rand;
+	private GameLogic gl;
+	private int boardSize;
+	
+	public AIEasy(GameLogic gl) {
+		this.gl = gl;
+		boardSize = gl.getBoard().length;
+		rand = new Random(gl.getBoard().hashCode());
+	}
+	
+	@Override
+	public void calculateNextMove() {
+		char[][] board = gl.getBoard();
+		int row = rand.nextInt(boardSize);
+		int col = rand.nextInt(boardSize);
+		gl.setField(row, col, AI_CHAR);
+	}
+	
+}

src/main/java/de/tims/tictactoe/ai/TicTacToeAI.java

@@ -0,0 +1,5 @@
+package de.tims.tictactoe.ai;
+
+public interface TicTacToeAI {
+	void calculateNextMove();
+}

src/test/java/de/tims/tictactoe/ai/AIEasyTest.java

@@ -0,0 +1,41 @@
+package de.tims.tictactoe.ai;
+
+import static org.mockito.Mockito.*;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.ArgumentMatcher;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import de.tims.tictactoe.GameLogic;
+
+@ExtendWith(MockitoExtension.class)
+class AIEasyTest {
+	static int size = 3;
+	
+	@Mock
+	private GameLogic gl;
+
+	@Test
+	void emptyBoardChooseRandomField() {
+		char realChar = 'o';
+		doReturn(new char[][] { {'-', '-', '-'}, {'-', '-', '-'}, {'-', '-', '-'} }).when(gl).getBoard();
+		
+		TicTacToeAI ai = new AIEasy(gl);
+		
+		//run method 100 times, because of random generator
+		for (int i = 0; i < 100; i++) {
+			ai.calculateNextMove();
+		}
+			
+		verify(gl, times(100)).setField(intThat(new ChooseRandomFieldMatcher()), intThat(new ChooseRandomFieldMatcher()), eq(realChar));
+	}
+	
+	private static class ChooseRandomFieldMatcher implements ArgumentMatcher<Integer> {
+		@Override
+		public boolean matches(Integer argument) {
+			return argument.intValue() >= 0 && argument.intValue() < size;
+		}
+	}
+}