Check Important Feature Combinations

TEST-CHECK-IMPORTANT-FEATURE-COMBINATIONS

Summary

Exercise default, disabled-default, all-feature, and important feature-pair builds. Feature flags change APIs and compile paths, so use a risk-based matrix instead of every combo.

Rule

Test all features and important feature combinations.

Why

Rust feature flags can change public API, optional dependencies, cfg-gated docs, and compile paths. Testing only the default feature set can miss that no-default-features, all-features, or important feature pairs no longer compile or no longer expose the documented API.

Helps

Catches feature-gated regressions before downstream users combine features differently than the maintainer did.

Limits

Do not test every theoretical feature combination when the matrix explodes. Choose default, no-default, all-features, each-feature, and important known interactions based on risk.

Agent Instruction

Test all features and important feature combinations because rust feature flags can change public API,
optional dependencies, cfg-gated docs, and compile paths.

Mechanisms

Supported by cargo hack, selected CI matrices, feature-specific doctests, cargo tree -e features, and documented feature support policy.