check for correct throws

src/test/java/dotsandboxes/DotsAndBoxesGridTest.java

@@ -2,8 +2,6 @@ package dotsandboxes;
 
 import static org.junit.jupiter.api.Assertions.*;
 
-import dotsandboxes.DotsAndBoxesGrid;
-import dotsandboxes.DotsAndBoxesUI;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.junit.jupiter.api.*;
@@ -108,14 +106,14 @@ public class DotsAndBoxesGridTest {
      */
 
     assertThrows(
-      RuntimeException.class,
+      IndexOutOfBoundsException.class,
       () -> {
         case1.drawHorizontal(-1, 0, 0);
       }
     );
 
     assertThrows(
-      RuntimeException.class,
+      IndexOutOfBoundsException.class,
       () -> {
         case1.drawHorizontal(width, 0, 0);
       }