refactoring: optimized bishop move validation

fh.fd.ci.client/src/main/java/de/fd/fh/FigureBishop.java

@@ -10,11 +10,9 @@ public class FigureBishop extends Figure
             return false;
         }
 
-        if (dst - src == 1 || dst - src == 6
-            || dst - src == 10) // 1 Feld nach rechts
-        {
+        if ((dst-src) % 7 != 0
+            && (dst-src) % 9 != 0)
             return false;
-        }
 
         return super.moveAllowed(src, dst, field);
     }

fh.fd.ci.client/src/test/java/de/fd/fh/FigureBishopTest.java

@@ -2,7 +2,7 @@ package de.fd.fh;
 
 import org.junit.jupiter.api.Test;
 
-import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 
 class FigureBishopTest
 {
@@ -42,10 +42,13 @@ class FigureBishopTest
     }
 
     @Test
-    void checkValidMovesBishopRight3()
+    void checkInvalidMovesBishopRight3()
     {
         Figure f = new FigureBishop();
 
-        assertFalse(f.moveAllowed(45, 55, field));
+        int src = Figure.fieldLength * 5 + 5;
+        int dst = src + 10;
+
+        assertFalse(f.moveAllowed(src, dst, field));
     }
 }