datatest-mini

Minimal proc macro for generating test functions from fixture files. A lightweight drop-in replacement for datatest-stable.

Usage

Add to your Cargo.toml:

[dev-dependencies]
datatest-mini = "0.4"

Create a test harness (e.g., tests/harness.rs):

use std::path::Path;

fn run_test(path: &Path, content: &str) -> Result<(), Box<dyn std::error::Error>> {
    // path: absolute path to the fixture file
    // content: file content read at runtime via std::fs::read_to_string
    Ok(())
}

datatest_mini::harness! {
    { test = run_test, root = "tests/fixtures", pattern = r"^[^/]+\.txt$" },
}

Each file matching the pattern generates a separate #[test] function, so you get individual pass/fail results per fixture.

Multiple test sets

datatest_mini::harness! {
    { test = test_parsing, root = "tests/parse_fixtures", pattern = r"\.txt$" },
    { test = test_codegen, root = "tests/codegen_fixtures", pattern = r"\.wado$" },
}

Async tests

async fn run_async_test(path: &Path, content: &str) -> Result<(), Box<dyn std::error::Error>> {
    Ok(())
}

datatest_mini::harness! {
    // Uses #[tokio::test] by default
    { test = run_async_test, root = "tests/fixtures", pattern = r"\.txt$", async },
    // Custom attribute
    { test = run_async_test, root = "tests/fixtures", pattern = r"\.txt$",
      async, attr = r#"tokio::test(flavor = "multi_thread")"# },
}

The attr parameter can also be used without async for sync tests with custom attributes:

datatest_mini::harness! {
    { test = run_test, root = "tests/fixtures", pattern = r"\.txt$", attr = "googletest::test" },
}

Parameters

Parameter	Description
test	Test function with signature fn(&Path, &str) -> Result<(), Box<dyn Error>>
root	Path to the fixture directory (relative to Cargo.toml)
pattern	Regex pattern matched against relative file paths
async	(optional) Generate async fn tests. Defaults to #[tokio::test]
attr	(optional) Custom test attribute (e.g., "tokio::test(flavor = \"multi_thread\")")
ignore_if_env	(optional) Env var name, or ["A", "B"]. Mark the test #[ignore] if any is set
ignore_unless_env	(optional) Env var name, or ["A", "B"]. Mark the test #[ignore] unless any is set

Ignoring tests by environment variable

datatest_mini::harness! {
    // Slow tests: run only in CI or when WADO_FULL_TEST is set, ignored otherwise.
    { test = slow_test, root = "tests/fixtures", pattern = r"\.txt$",
      ignore_unless_env = ["CI", "WADO_FULL_TEST"] },
    // Kill switch: ignore whenever DATATEST_MINI_SKIP is set.
    { test = run_test, root = "tests/fixtures", pattern = r"\.txt$",
      ignore_if_env = "DATATEST_MINI_SKIP" },
}

The env vars are read at compile time (macro expansion) and baked into a real #[ignore = "..."], so ignored tests show as ignored (not passing) and do no file I/O. Run them on demand without rebuilding via cargo test -- --ignored (only ignored) or cargo test -- --include-ignored (all).

Because the decision is made at compile time, changing an env var does not automatically rebuild — re-expand the macro by touching the test file (the same step you already need to pick up added/removed fixtures) or run cargo clean. The auto-tracking API proc_macro::tracked_env is nightly-only.

License

MIT