added integration test for missing creds

backend/src/test/java/com/vaessl/app/connection/HomeboxIntegrationTest.java

@@ -193,6 +193,18 @@ class HomeboxIntegrationTest {
         }
     }
 
+    @Test
+    void shouldReturnEmptyCredentialsExceptionWhenCredsAreMissing() {
+        ConnectionRequest missingCredentials = new ConnectionRequest(MOCK_URL, HOMEBOX.getValue(), TEST_USER, null,
+                false);
+
+        ResponseEntity<String> response = restTemplate.postForEntity(LOGIN.getValue(), missingCredentials,
+                String.class);
+
+        assertThat(response.getStatusCode()).isEqualTo(HttpStatus.BAD_REQUEST);
+        assertThat(response.getBody()).contains(BAD_REQUEST_EMPTY_FIELDS.getMessage());
+    }
+
     /**
      * Creates a valid connection request with a mock Api throuh
      * WireMockRuntimeInfo.