message: fixed tests in cosmwasm_vm
diff: @@ -436,8 +436,7 @@ mod test {
  let ctx = instance.context_mut();
  leave_default_data(ctx);
  - let result = do_write::<MS, MQ>(ctx, key_ptr, value_ptr);
  - assert_eq!(result.unwrap(), errors::NONE);
  + do_write::<MS, MQ>(ctx, key_ptr, value_ptr).unwrap();
  let (val, _used_gas) = with_storage_from_context::<MS, MQ, _, _>(ctx, |store| {
  Ok(store.get(b"new storage key").expect("error getting value"))
  @@ -456,8 +455,7 @@ mod test {
  let ctx = instance.context_mut();
  leave_default_data(ctx);
  - let result = do_write::<MS, MQ>(ctx, key_ptr, value_ptr);
  - assert_eq!(result.unwrap(), errors::NONE);
  + do_write::<MS, MQ>(ctx, key_ptr, value_ptr).unwrap();
  let (val, _used_gas) = with_storage_from_context::<MS, MQ, _, _>(ctx, |store| {
  Ok(store.get(KEY1).expect("error getting value"))
  @@ -476,8 +474,7 @@ mod test {
  let ctx = instance.context_mut();
  leave_default_data(ctx);
  - let result = do_write::<MS, MQ>(ctx, key_ptr, value_ptr);
  - assert_eq!(result.unwrap(), errors::NONE);
  + do_write::<MS, MQ>(ctx, key_ptr, value_ptr).unwrap();
  let (val, _used_gas) = with_storage_from_context::<MS, MQ, _, _>(ctx, |store| {
  Ok(store.get(b"new storage key").expect("error getting value"))
  @@ -496,8 +493,7 @@ mod test {
  let ctx = instance.context_mut();
  leave_default_data(ctx);
  - let result = do_write::<MS, MQ>(ctx, key_ptr, value_ptr);
  - assert_eq!(result.unwrap(), errors::REGION_READ_LENGTH_TOO_BIG);
  + do_write::<MS, MQ>(ctx, key_ptr, value_ptr).unwrap_err();
  }
  #[test]
  @@ -510,8 +506,7 @@ mod test {
  let ctx = instance.context_mut();
  leave_default_data(ctx);
  - let result = do_write::<MS, MQ>(ctx, key_ptr, value_ptr);
  - assert_eq!(result.unwrap(), errors::REGION_READ_LENGTH_TOO_BIG);
  + do_write::<MS, MQ>(ctx, key_ptr, value_ptr).unwrap_err();
  }
  #[test]
  