57 lines (38 loc) · 2.13 KB

Air

Project Overview

Air is an R language server and formatter written in Rust. Workspace crate layout under crates/ with a CLI binary in crates/air/.

Rust edition and version are reported in workspace level Cargo.toml
Uses biome_formatter for the formatting engine and ignore crate for file walking
Config file: air.toml discovered by walking up directory ancestors
Snapshot testing with insta

Code Style

Imports

One item per use line, no {} grouping
Grouped in order: std, external crates, crate/super, with groups separated by blank lines

Error Handling

thiserror::Error for structured error enums; manual Display impls when messages need custom formatting (e.g. path underlining)
CLI-facing errors: log with tracing::error! and return Ok(ExitStatus::Error). Reserve anyhow::Error for truly unexpected errors.
tracing::trace! for file inclusion/exclusion decisions

Functions

Normalize paths with fs::normalize_path at function boundaries
Prefer returning structured enums (e.g. FormattedSource::Changed/Unchanged) over booleans

Comments

Explain the "why", not the "what"
Reference GitHub issues when behavior is motivated by a specific bug report

Testing

Running Tests

Use just test to run tests via nextest, NOT cargo test
Example: just test -p workspace --lib discovery::test
Passes arguments through to cargo nextest run

Unit Tests

#[cfg(test)] mod test at the bottom of the source file
Use tempfile::TempDir, immediately shadow: let tempdir = TempDir::new()?; let tempdir = tempdir.path();
Use anyhow::Result<()> as test return type
Write files into temp dirs to set up test fixtures inline

Integration Tests

Live in crates/air/tests/integration/
insta::assert_snapshot! for CLI output assertions
Build Command with method chaining: .current_dir(), .arg(), .run() or .run_with_stdin()
.remove_arguments() when snapshot would contain machine-specific absolute paths
.normalize_os_path_separator() for cross-platform path assertions
Test both the happy path and the exclusion/rejection path