Add unit tests to detect assignment errors

src/test/java/dotsandboxes/DotsAndBoxesGridTest.java

@@ -2,8 +2,6 @@ package dotsandboxes;
 
 import org.junit.jupiter.api.*;
 import static org.junit.jupiter.api.Assertions.*;
-import static org.junit.jupiter.api.Assumptions.*;
-
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
@@ -27,5 +25,41 @@ public class DotsAndBoxesGridTest {
         assertTrue(true);
     }
 
-    // FIXME: You need to write tests for the two known bugs in the code.
+    // Test cases for known bugs
+
+    @Test
+    public void testSquareCompletionBug() {
+        logger.info("Testing square completion logic");
+
+        // Create a new game grid
+        DotsAndBoxesGrid grid = new DotsAndBoxesGrid();
+
+        // Draw lines to form a square
+        grid.drawLine(0, 0, 0, 1); // Top horizontal line
+        grid.drawLine(0, 0, 1, 0); // Left vertical line
+        grid.drawLine(0, 1, 1, 1); // Bottom horizontal line
+        grid.drawLine(1, 0, 1, 1); // Right vertical line
+
+        // Test if the square at (0, 0) is complete
+        boolean isComplete = grid.isSquareComplete(0, 0);
+        
+        // The bug is that isSquareComplete always returns true
+        assertFalse(isComplete, "The square completion check should fail because the method is broken.");
+    }
+
+    @Test
+    public void testDrawLineTwiceThrowsException() {
+        logger.info("Testing drawing the same line twice throws exception");
+
+        // Create a new game grid
+        DotsAndBoxesGrid grid = new DotsAndBoxesGrid();
+
+        // Draw a line once
+        grid.drawLine(0, 0, 0, 1);
+        
+        // Attempt to draw the same line again
+        assertThrows(IllegalStateException.class, () -> {
+            grid.drawLine(0, 0, 0, 1);
+        }, "Drawing the same line twice should throw IllegalStateException.");
+    }
 }