fixture-tree

Generate Rust source code that mirrors a filesystem directory as a module tree, providing zero-cost accessors for file paths and contents at compile time.

fixture-tree is intended for use from build scripts (build.rs). It walks a directory of fixture files (test data, configs, model weights, etc.) and emits a .rs file where every directory becomes a mod and every file becomes a function returning its path and, optionally, its contents via include_str! or include_bytes!.

This is particularly useful when you rely on many static files for testing specific use-cases. It gives you code-completion for your fixture paths and turns stale or mistyped paths into compile errors.

Quick start

Add fixture-tree as a build dependency:

[build-dependencies]
fixture-tree = "0.1"

Create a build.rs:

fn main() {
    fixture_tree::Config::new()
        .from_path("fixtures")           // relative to CARGO_MANIFEST_DIR
        .with_ext("json")                // only include .json files
        .with_ext_as_string("json")      // embed contents via include_str!
        .build()
        .unwrap()
        .generate_fixtures()
        .unwrap();
}

Then include the generated file in your library or test code:

include!(concat!(env!("OUT_DIR"), "/fixture_tree_autogen.rs"));

#[test]
fn read_fixture() {
    let (path, contents) = configs::pass::basic();
    assert!(path.exists());
    assert!(contents.contains("ok"));
}

Features

Enable it in your Cargo.toml:

[build-dependencies]
fixture-tree = { version = "0.1", features = ["regex"] }

Path handling

When the source directory is under CARGO_MANIFEST_DIR (the typical case), generated paths use concat!(env!("CARGO_MANIFEST_DIR"), "/...") so they resolve correctly on any machine. If the source directory is outside the manifest (e.g. a system temp directory), absolute paths are emitted instead.

Filtering

Files can be filtered in several ways:

• By extension — with_ext / with_exts restrict which file extensions are walked. An empty list means "all extensions".
• By regex (requires the regex feature) — with_allow_pattern / with_allow_patterns match against the file's path relative to the source root. When at least one regex is configured a file must match any of them to be included.
• By path exclusion — without_path / without_paths exclude entire directory subtrees by their path relative to the source root.

Generated code shape

For each directory a path() function is emitted. For each matched file a function named after the file stem (lowercased, dashes replaced with underscores) is emitted:

Empty directories are pruned from the output.

License

Licensed under MIT license.