message: added call_migrate_works function in test modules.
diff: @@ -197,7 +197,7 @@ where
  mod tests {
  use super::*;
  use crate::testing::{mock_env, mock_info, mock_instance};
  - use cosmwasm_std::{coins, Empty};
  + use cosmwasm_std::{coins, Empty, HumanAddr};
  static CONTRACT: &[u8] = include_bytes!("../testdata/hackatom.wasm");
  @@ -232,6 +232,35 @@ mod tests {
  .unwrap();
  }
  + #[test]
  + fn call_migrate_works() {
  + let mut instance = mock_instance(&CONTRACT, &[]);
  +
  + // init
  + let info = mock_info("creator", &coins(1000, "earth"));
  + let msg = r#"{"verifier": "verifies", "beneficiary": "benefits"}"#.as_bytes();
  + call_init::<_, _, _, Empty>(&mut instance, &mock_env(), &info, msg)
  + .unwrap()
  + .unwrap();
  +
  + // change the verifier via migrate
  + let new_verifier = HumanAddr::from("someone else");
  + let msg = MigrateMsg {
  + verifier: new_verifier,
  + };
  + let info = mock_info(creator.as_str(), &[]);
  + let res = call_migrate(&mut instance, &mock_env(), &info, msg);
  + assert_eq!(0, res.messages.len());
  +
  + // query the new_verifier with verifier
  + let msg = r#"{"verifier":{}}"#.as_bytes();
  + let contract_result = call_query(&mut instance, &mock_env(), msg).unwrap();
  + let query_response = contract_result.unwrap();
  + assert_eq!(query_response.verifier, new_verifier);
  +
  +
  + }
  +
  #[test]
  fn call_query_works() {
  let mut instance = mock_instance(&CONTRACT, &[]);
  