Getting started

Install the CLI

cargo install cargo-bylaw
cargo bylaw --version

Cargo discovers installed subcommands through PATH. Cargo installs binaries into $CARGO_HOME/bin, which defaults to ~/.cargo/bin.

If Cargo reports no such command: bylaw on macOS or Linux, add the directory to PATH, persist the same setting in the shell profile, and restart the shell:

export PATH="${CARGO_HOME:-$HOME/.cargo}/bin:$PATH"
cargo bylaw --version

For PowerShell on Windows:

$env:Path += ";$HOME\.cargo\bin"
cargo bylaw --version

For architecture rules written as Rust tests, add the library as a development dependency:

[dev-dependencies]
bylaw = "0.1"

Configure the CLI

Create bylaw.toml beside the workspace Cargo.toml:

version = 1

[selectors.domain]
modules = ["shop::domain::**"]

[selectors.persistence]
modules = ["shop::persistence::**"]

[[rule]]
id = "domain-is-internal"
kind = "forbid-dependencies"
from = "domain"
to = "persistence"
scope = "both"
because = "domain policy must not depend on infrastructure"

Run the check. The check subcommand is required; cargo bylaw alone does not run architecture rules.

cargo bylaw check

Write a Rust architecture test

#![allow(unused)]
fn main() {
use bylaw::analyzer::{AnalysisOptions, analyze_workspace};
use bylaw::prelude::*;

#[test]
fn architecture_is_valid() -> Result<(), Box<dyn std::error::Error>> {
    let manifest_path = format!("{}/Cargo.toml", env!("CARGO_MANIFEST_DIR")).into();
    let graph = analyze_workspace(&AnalysisOptions {
        manifest_path,
        ..AnalysisOptions::default()
    })?;

    rules()
        .forbid_dependencies(
            "domain-is-internal",
            modules(["shop::domain::**"]),
            modules(["shop::persistence::**"]),
        )
        .check(&graph)?
        .assert();

    Ok(())
}
}

The graph is imported once and can be evaluated by any number of built-in or custom rules.

Analyze a different build configuration

Architecture depends on the selected features, target, and Cargo targets:

[analysis]
features = ["postgres"]
target = "x86_64-unknown-linux-gnu"
target_kinds = ["library", "binary"]

See Configuration for every option.