App-chain testkit

org.yanoproject:yano-appchain-testkit provides a JUnit 5 extension with generated member keys, temporary ledgers, and real socket connections between embedded nodes.

import org.yanoproject.appchain.testkit.AppChainCluster;
import org.yanoproject.appchain.testkit.AppChainClusterHandle;
import org.junit.jupiter.api.Test;
import java.nio.charset.StandardCharsets;

@AppChainCluster(nodes = 3, stateMachine = "ordered-log")
class SharedLogTest {
    @Test
    void finalizesOnEveryMember(AppChainClusterHandle cluster) throws Exception {
        String id = cluster.node(1).submit(
                "orders", "order-1".getBytes(StandardCharsets.UTF_8));
        cluster.awaitFinalized(id);
    }
}

awaitFinalized waits for the message on all nodes and fails on timeout. Node 0 is the sequencer. The default threshold = 0 selects all members; blockIntervalMs defaults to 300. You can set the chain ID, state-machine ID, member count, threshold, and proposer tick interval on the annotation.

This is an integration fixture, not a simulation of Byzantine peers, adversarial timing, L1 rollback, or production load. Add workload-specific assertions and separate tests for those concerns.

For effect executor plugins, the module also supplies provider-neutral conformance suites and an EffectRuntimeHarness. See the module source and contracts in the repository.