Add unit tests for detecting bugs in the main.js code

src/test/java/dotsandboxes/DotsAndBoxesGridTest.java

@@ -9,26 +9,65 @@ import org.apache.logging.log4j.Logger;
 
 public class DotsAndBoxesGridTest {
     /*
-     * Because Test classes are classes, they can have fields, and can have static fields.
-     * This field is a logger. Loggers are like a more advanced println, for writing messages out to the console or a log file.
+     * Because Test classes are classes, they can have fields, and can have static
+     * fields.
+     * This field is a logger. Loggers are like a more advanced println, for writing
+     * messages out to the console or a log file.
      */
     private static final Logger logger = LogManager.getLogger(DotsAndBoxesGridTest.class);
 
     /*
      * Tests are functions that have an @Test annotation before them.
-     * The typical format of a test is that it contains some code that does something, and then one
+     * The typical format of a test is that it contains some code that does
+     * something, and then one
      * or more assertions to check that a condition holds.
      *
      * This is a dummy test just to show that the test suite itself runs
      */
-
-     assertTrue(true);
-
     @Test
     public void testTestSuiteRuns() {
         logger.info("Dummy test to show the test suite runs");
         assertTrue(true);
     }
 
-    // FIXME: You need to write tests for the two known bugs in the code.
+    @Test
+    public void testBoxIsIncomplete() {
+        DotsAndBoxesGrid grid = new DotsAndBoxesGrid(4, 4, 2);
+        int x = 0, y = 0, player = 1;
+
+        grid.drawHorizontal(x, y, player);
+        grid.drawHorizontal(x + 1, y, player);
+        grid.drawVertical(x, y, player);
+
+        assertFalse(grid.boxComplete(x, y), "Box not fully drawn!");
+
+    }
+
+    @Test
+    public void testForAlreadyDrawnHorizontalLine() {
+        DotsAndBoxesGrid grid = new DotsAndBoxesGrid(4, 5, 2);
+        int x = 0, y = 0, player = 1;
+
+        grid.drawHorizontal(x, y, player);
+        grid.drawHorizontal(x + 1, y, player);
+        grid.drawVertical(x, y, player);
+
+        assertThrows(IllegalStateException.class, () -> {
+            grid.drawHorizontal(x, y, player);
+        });
+    }
+
+    @Test
+    public void testForAlreadyDrawnVerticalLine() {
+        DotsAndBoxesGrid grid = new DotsAndBoxesGrid(4, 5, 2);
+        int x = 0, y = 0, player = 1;
+
+        grid.drawHorizontal(x, y, player);
+        grid.drawHorizontal(x + 1, y, player);
+        grid.drawVertical(x, y, player);
+
+        assertThrows(IllegalStateException.class, () -> {
+            grid.drawVertical(x, y, player);
+        });
+    }
 }
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