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Subscription Management SC

This lab walks through a real-world subscription smart contract. You will practice cloning a contract that lives as a git submodule, compiling it with the sc-meta CLI, generating a Rust interactor, and tightening both the contract logic and its scenario tests.

Key takeaways:

  • sc-meta orchestrates compilation, snippets, and tests for MultiversX smart contracts.
  • Payable endpoints must enforce economic rules explicitly; tests highlight the missing checks.
  • Interactors are code-generated and let you script deployments and endpoint calls from Rust.

1. Clone the submodule​

The util/subscription-sc folder is a submodule. Clone and pull it in before you start:

git clone https://github.com/andreiblt1304/subscription-sc.git # HTTPS
git clone git@github.com:andreiblt1304/subscription-sc.git # SSH

Inspect the contract sources (src/lib.rs) and the black-box tests under tests/.

2. Build with sc-meta​

From the root of the crate, compile the contract:

sc-meta all build

You should see the resulting artifacts in output/.

3. Generate the interactor​

Produce a Rust interactor so you can script deployments and calls:

sc-meta all snippets

This creates an interactor/ project. Open it to understand the generated proxy code and how endpoint calls are exercised from Rust.

4. Run the scenario tests​

Trigger the test harness:

sc-meta test

The add_new_subscription_should_require_payment test is expected to fail initially. Use the failure to trace how the contract handles the payment checks.

5. Fix the contract and the tests​

  • Enforce that add_new_subscription only records a subscription when the caller pays exactly the plan price. Hint: read the call_value() before storing the subscription.
  • Augment the test so it also covers the happy path (send the correct payment and assert the on-chain subscription mirrors it). The helper utilities in tests/subscription_blackbox_setup.rs already handle caller addresses; extend them to accept an EGLD amount.

Re-run sc-meta test until the suite is green.

Practice​

  • Finish the contract fix and extend the test so it validates both failure (no payment) and success (exact price) scenarios.