message: Test results of call_function
diff: @@ -364,15 +364,23 @@ mod test {
  let instance = mock_instance(&CONTRACT, &[]);
  // can call function few times
  - let _ptr1 = instance
  + let result = instance
  .call_function("allocate", &[0u32.into()])
  .expect("error calling allocate");
  - let _ptr2 = instance
  + assert_eq!(result.len(), 1);
  + assert_ne!(result[0].unwrap_i32(), 0);
  +
  + let result = instance
  .call_function("allocate", &[1u32.into()])
  .expect("error calling allocate");
  - let _ptr3 = instance
  + assert_eq!(result.len(), 1);
  + assert_ne!(result[0].unwrap_i32(), 0);
  +
  + let result = instance
  .call_function("allocate", &[33u32.into()])
  .expect("error calling allocate");
  + assert_eq!(result.len(), 1);
  + assert_ne!(result[0].unwrap_i32(), 0);
  }
  #[test]
  