fixtura lets you declare exactly what each test parameter depends on and fakes
everything else automatically. Built on fake-rs.

How it works

Add #[cfg_attr(test, derive(fake::Dummy))] to your struct, then declare test
parameters with only the fields that matter:

#[fixtura::test]
fn inactive_users_cannot_checkout(
    #[fixtura(active = false)] user: User,
    order: Order,
) {
    assert!(checkout(&user, &order).is_err());
}

Only active is pinned because only active drives the logic. Everything
else — IDs, names, timestamps — is faked automatically.

Cross-argument references work too:

#[fixtura::test]
fn order_belongs_to_user(
    user: User,
    #[fixtura(user_id = user.id)] order: Order,
) {
    assert_eq!(order.user_id, user.id);
}

Real-world result

I migrated CILens, a CI analytics tool I built, to fixtura:

• 5 create_test_* helpers deleted
• Test suite shrank by 25%
• ~120 struct fields that were hardcoded for no reason now freely faked

The before/after is in the PRs if you want to see what an actual migration
looks like:

• feat: migrate test suite to fixtura by dsalaza4 · Pull Request #12 · dsalaza4/cilens · GitHub — initial migration
• test(core): unpin fields not needed by test assertions by dsalaza4 · Pull Request #13 · dsalaza4/cilens · GitHub — removing unnecessary pins

Limitations I'm honest about

• Tuple structs: field overrides aren't supported by position, only by name.
  Workaround: use a named struct or wrap the tuple struct.
• Async tests: works fine, but the attribute ordering matters (#[fixtura::test]
  must come before async runtime attributes like #[tokio::test]).
• Requires fake::Dummy on your types — either derive it or impl manually.

Links

• crates.io: crates.io: Rust Package Registry
• GitHub: GitHub - dsalaza4/fixtura: Declarative fake data injection for Rust tests, built on fake-rs. · GitHub
• MSRV: 1.85 (Rust 2024 edition)

Happy to answer questions. Feedback on the API or missing features welcome.

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