Implement Interface

README.md

@@ -8,4 +8,8 @@ In the Initial State I have the implementation of the LifeBoard exposed and refe
 
 ## Defined Interface
 
-The first step is defining an interface which encapsulates the actions I am interested in.
+The first step is defining an interface which encapsulates the actions I am interested in.
+
+## Implement Interface
+
+Next I implement the interface, without changing the classes which access the board object.  All my tests are still green and I could push to master without breaking things.

src/main/java/Board.java

@@ -7,6 +7,6 @@ public interface Board {
 
     public int at(int x, int y);
 
-    public void set(int x, int y);
+    public void set(int x, int y, int value);
 
 }

src/main/java/LifeBoard.java

@@ -1,8 +1,32 @@
 /**
  * Created by clay on 4/15/17.
  */
-public class LifeBoard {
+public class LifeBoard implements Board {
     public static final int X_MAX = 50;
     public static final int Y_MAX = 50;
     static public boolean[][] value = new boolean[X_MAX][Y_MAX];
+
+
+    public void clear() {
+        for(int x=0; x < X_MAX; ++x) {
+            for(int y=0; y < Y_MAX; ++y) {
+                value[x][y] = false;
+            }
+        }
+    }
+
+    public int at(int x, int y) {
+        if (value[x][y]) {
+            return 1;
+        }
+        return 0;
+    }
+
+    public void set(int x, int y, int value) {
+        if (0 == value) {
+            this.value[x][y] = false;
+        } else {
+            this.value[x][y] = true;
+        }
+    }
 }

src/test/java/LifeBoardTest.java

@@ -0,0 +1,46 @@
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.*;
+
+/**
+ * Created by clay on 4/15/17.
+ */
+public class LifeBoardTest {
+
+    private LifeBoard board;
+
+    @Before
+    public void setUp() {
+        board = new LifeBoard();
+        board.clear();
+    }
+
+    @Test
+    public void clear_byDefault_setsAllValuesToFalse() {
+        board.value[10][10] = true;
+        board.clear();
+        assertThat(board.value[10][10], is(false));
+    }
+
+    @Test
+    public void at_forATrueCell_returnsOne() {
+        board.value[10][10] = true;
+        assertThat(board.at(10, 10), is(1));
+    }
+
+    @Test
+    public void at_forFalseCell_returnsZero() {
+        board.value[10][10] = false;
+        assertThat(board.at(10, 10), is(0));
+    }
+
+    @Test
+    public void set_givenZero_willReturnZeroFromAt() {
+        board.value[10][10] = true;
+        board.set(10, 10, 0);
+        assertThat(board.at(10, 10), is(0));
+    }
+
+}