diff --git a/src/test/test_duellist_spielesammlung_projekt.c b/src/test/test_duellist_spielesammlung_projekt.c
index f6a6664..c74dc9e 100644
--- a/src/test/test_duellist_spielesammlung_projekt.c
+++ b/src/test/test_duellist_spielesammlung_projekt.c
@@ -59,7 +59,19 @@ void test_horizontal_win(void) {
     // Assert
     TEST_ASSERT_EQUAL(GAME_WIN, result);
 }
+void test_diagonal_win(void) {
+    // Arrange
+    TicTacToeGame game = { .board = {{PLAYER_X, EMPTY, EMPTY},
+                                     {EMPTY, PLAYER_X, EMPTY},
+                                     {EMPTY, EMPTY, PLAYER_X}},
+                          .currentPlayer = PLAYER_O };
 
+    // Act
+    GameResult result = checkGameResult(&game);
+
+    // Assert
+    TEST_ASSERT_EQUAL(GAME_WIN, result);
+}