MultiversX Testing Handbook

This skill provides expert guidance on the 3 layers of MultiversX testing: RustVM Unit Tests, Mandos Integration Tests, and Chain Simulation.

1. RustVM Unit Tests

• •Location: #[cfg(test)] modules within contract files or tests/ directory.
• •Speed: Instant.
• •Scope: Internal logic, strict math, private functions.
• •Mocking: Use multiversx_sc_scenario::imports::* to mock the blockchain environment (blockchain_mock.set_caller(addr)).

2. Mandos Scenarios (.scen.json)

• •Location: scenarios/ directory.
• •Requirement: "If it's an endpoint, it MUST have a Mandos test."
• •Execution:
  • •cargo test-gen generates Rust wrappers for scenarios.
  • •cargo test runs them.
• •Key Concepts:
  • •step: setState: Initialize accounts and balances.
  • •step: scCall: Execute endpoint.
  • •step: checkState: Verify storage matches expected values.

3. Chain Simulator (mx-chain-simulator-go)

• •Location: Separate system test suite (often Go or Python).
• •Scope: Interaction with Node API, complex cross-shard reorgs, off-chain indexing.
• •Tool: Use POST /simulator/generate-blocks to force execution.

4. Coverage Strategy

• •Money In/Out: 100% Mandos coverage required.
• •View Functions: Unit test coverage sufficient.
• •Access Control: Explicit negative tests (expect error 4) for unauthorized calls.