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rustmultiversx

Creating a new ManagedBuffer in Rust tests panics "called Option::unwrap() on a None"

I'm trying to create a new ManagedBuffer in a rust test, but the tests panic. I've tried using both, the ManagedBuffer::new_from_bytes function and the managed_buffer! macro, but both of them result in the same error:

thread 'use_managed_buffer_new_from_bytes' panicked at 'called Option::unwrap() on a None value', /home/mccuna/elrondsdk/vendor-rust/registry/src/github.com-1ecc6299db9ec823/elrond-wasm-debug-0.27.4/src/tx_mock/tx_context_stack.rs:16:28

thread 'use_managed_buffer_macro' panicked at 'called Option::unwrap() on a None value', /home/mccuna/elrondsdk/vendor-rust/registry/src/github.com-1ecc6299db9ec823/elrond-wasm-debug-0.27.4/src/tx_mock/tx_context_stack.rs:16:28

// test_test.rs
use elrond_wasm::types::ManagedBuffer;
use elrond_wasm_debug::{managed_buffer, tx_mock::TxContextRef};

#[test]
fn use_managed_buffer_macro() {
  let test: ManagedBuffer<TxContextRef> = managed_buffer!(b"Test");
}

#[test]
fn use_managed_buffer_new_from_bytes() {
  let test = ManagedBuffer::<TxContextRef>::new_from_bytes(b"Test");
}

Versions used:

[dependencies.elrond-wasm]
version = "0.27.4"

[dev-dependencies.elrond-wasm-debug]
version = "0.27.4"
Solution

  • Close to the end of this docs section it's mentioned that "Keep in mind you can't create managed types outside of the execute_tx functions. If you need to do that, you should use blockchain_wrapper.execute_in_managed_environment()"

    So, the default solution to creating a ManagedBuffer from bytes is to make the call inside a blockchain_wrapper.execute_in_managed_environment() closure.

    An alternative to blockchain_wrapper.execute_in_managed_environment() is to call let _ = DebugApi::dummy(); before calling ManagedBuffer::new_from_bytes. DebugApi::dummy() instantiates the required mocks for the ManagedBuffer::new_from_bytes to work in Rust tests.

    P.s.: DebugApi::dummy() works with static fields. I've not checked but calling it multiple times might result in issues
    P.p.s: thank you Martin!