Test minus

src/test/test_duellist_spielesammlung_projekt.c

@@ -472,7 +472,18 @@ void test_addition(void)
     TEST_ASSERT_EQUAL_INT(15, result);
 }
 
+void test_subtraction(void)
+{
+    /* arrange */
+    int a = 15;
+    int b = 10;
 
+    /* act */
+    int result = subtraction(a, b);
+
+    /* assert */
+    TEST_ASSERT_EQUAL_INT(5, result);
+}