5. Build and test components

cargo install cargo-binstall
cargo binstall cargo-component warg-cli wkg --locked --no-confirm --force

# Configure default registry
wkg config --default-registry wa.dev

Build WASI component

Run the following command in your terminal to build your component.

make wasi-build

This command will build any components present in the /components directory, as well as auto-generate bindings and compile the components to WASM. The output will be placed in the compiled directory.

make build

Testing and debugging

You can use the following command to test the WASM component locally. This command is handy for testing components without having to deploy WAVS.

An ID of 1 is Bitcoin. Nothing will be saved on-chain, just the output of the component is shown.

COIN_MARKET_CAP_ID=1 make wasi-exec

This command runs your component locally in a simulated environment and lets you easily view print statements for debugging.

COIN_MARKET_CAP_ID is the ID of the asset to fetch the price for. This input is formatted as a bytes32 string using cast format-bytes32-string before being passed to the component.

Running this command in the oracle example will run the component, fetch the price of Bitcoin, and print the result. Visit the component walkthrough for more information on logging during testing and production.

Upon successful execution, you should receive a result similar to the following:

resp_data: Ok(PriceFeedData { symbol: "BTC", timestamp: "2025-02-14T01:23:03.963Z", price: 96761.74120116462 })
 INFO Fuel used:
1477653

Result (hex encoded):
7b2273796d626f6c223a22425443222c2274696d657374616d70223a22323032352d30322d31345430313a32333a30332e3936335a222c227072696365223a39363736312e37343132303131363436327d

Result (utf8):
{"symbol":"BTC","timestamp":"2025-02-14T01:23:03.963Z","price":96761.74120116462}

Custom triggers

When developing a custom trigger, you will need to update the template code in a few places:

1. The trigger contract itself in src/WavsTrigger.sol, which defines how triggers are created and emitted on-chain.
2. The wasi-exec command in the Makefile, which passes input data when testing WAVS components via --input `cast format-bytes32-string $(COIN_MARKET_CAP_ID)` . This simulates an Ethereum event during local execution.
3. The decode_trigger_event function in /components/eth-price-oracle/src/trigger.rs, which processes the trigger data and extracts relevant fields like trigger_id and data.
4. The run function in /components/eth-price-oracle/src/lib.rs, which calls decode_trigger_event, processes the extracted trigger data, and determines how to handle it.
5. The trigger script in /script/Trigger.s.sol, which calls the addTrigger function with the coinMarketCapID, used in this template for the oracle example.

Contract interfaces

You can view the code for the Solidity interfaces on the WAVS NPM package site: https://www.npmjs.com/package/@wavs/solidity?activeTab=code

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