Test Optimization

Advanced test optimization with cargo-nextest, property testing, and benchmarking.

cargo-nextest (Primary Test Runner)

cargo nextest run --all              # all tests
cargo nextest run --profile ci       # CI with retries + JUnit XML
cargo nextest run --profile nightly  # extended timeouts
cargo nextest run -E 'package(memory-core)'  # filterset DSL
cargo test --doc --all               # doctests (nextest limitation)

Configuration (.config/nextest.toml)

[profile.default]
retries = 0
slow-timeout = { period = "60s", terminate-after = 2 }
fail-fast = false

[profile.ci]
retries = 2
slow-timeout = { period = "30s", terminate-after = 3 }
failure-output = "immediate-final"
junit.path = "target/nextest/ci/junit.xml"

[profile.nightly]
retries = 3
slow-timeout = { period = "120s", terminate-after = 2 }

Mutation Testing (cargo-mutants)

Verifies tests actually catch bugs by injecting mutations:

cargo mutants -p memory-core --timeout 120 --jobs 4 -- --lib

• Acceptance: <20% missed mutants in core business logic
• Frequency: Nightly CI or pre-release
• Scope: Start with memory-core, expand incrementally

Property-Based Testing (proptest)

proptest! {
    #[test]
    fn serialization_roundtrip(episode in any_episode_strategy()) {
        let bytes = postcard::to_allocvec(&episode).unwrap();
        let decoded: Episode = postcard::from_bytes(&bytes).unwrap();
        assert_eq!(episode, decoded);
    }
}

Snapshot Testing (insta)

#[test]
fn test_mcp_response_format() {
    let response = build_tool_response("search_patterns", &params);
    insta::assert_json_snapshot!(response);
}

cargo insta test     # run snapshot tests
cargo insta review   # accept/reject changes

Performance Targets

Best Practices

• Use nextest profiles for dev/CI/nightly separation
• Implement property tests for serialization roundtrips and state machines
• Use snapshot tests for MCP responses, CLI output
• Run mutation testing before releases
• Monitor test duration and coverage trends

References

• ADR-033: Modern Testing Strategy
• TESTING.md