add findGameByIdTest to ServerAppTest

fh.fd.ci.server/src/test/java/de/fd/fh/ServerAppTest.java

@@ -179,5 +179,22 @@ class ServerAppTest
         assertNotNull(res);
         assertEquals(200, res.getStatus());
         then(gameController).should().createGame(any(), any());
+        then(gameController).shouldHaveNoMoreInteractions();
+    }
+
+    @Test
+    void testFindGameById() throws JsonProcessingException
+    {
+        when(gameController.findGameById(any(), any())).thenReturn(mock(Response.class));
+
+        final String url = "/games/12345";
+
+        ApiTestUtils.TestResponse<String> res = new ApiTestUtils<String>()
+                .request("GET", url, null, null, String.class);
+
+        assertNotNull(res);
+        assertEquals(200, res.getStatus());
+        then(gameController).should().findGameById(any(), any());
+        then(gameController).shouldHaveNoMoreInteractions();
     }
 }