project_detect/

lib.rs

//! Zero-config project type detection.
//!
//! Scans a directory for build system files (Cargo.toml, package.json, go.mod,
//! etc.) and returns the detected [`ProjectKind`] with ecosystem-specific
//! metadata. Supports 32 ecosystems out of the box.
//!
//! ```
//! use project_detect::{detect, ProjectKind};
//!
//! if let Some(kind) = detect(".") {
//!     println!("Detected: {} ({})", kind.label(), kind.detected_file());
//! }
//! ```

use std::path::{Path, PathBuf};
use std::process::{Command, Stdio};

// -- Public types ------------------------------------------------------------

/// Node.js package manager, detected from lockfile presence.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum NodePM {
    Bun,
    Pnpm,
    Yarn,
    Npm,
}

/// Kotlin build tool metadata.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum KotlinBuild {
    Gradle { wrapper: bool },
    Maven,
}

/// A detected project type with ecosystem-specific metadata.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum ProjectKind {
    // -- Language-specific (highest confidence) --
    Cargo,
    Go,
    Elixir { escript: bool },
    Python { uv: bool },
    Node { manager: NodePM },
    Kotlin { build: KotlinBuild },
    Gradle { wrapper: bool },
    Maven,
    Ruby,
    Swift,
    Xcode { workspace: bool },
    Zig,
    DotNet { sln: bool },
    Php,
    Dart { flutter: bool },
    Sbt,
    Haskell { stack: bool },
    Clojure { lein: bool },
    Rebar,
    Dune,
    Perl,
    Julia,
    R { renv: bool },
    Nim,
    Crystal,
    Vlang,
    Gleam,
    Lua,

    // -- Build systems (lower confidence) --
    Bazel,
    Meson,
    CMake,
    Make,
}

impl ProjectKind {
    /// Human-readable ecosystem name (e.g. "Rust", "Node.js").
    pub fn label(&self) -> &'static str {
        match self {
            Self::Cargo => "Rust",
            Self::Go => "Go",
            Self::Elixir { .. } => "Elixir",
            Self::Python { .. } => "Python",
            Self::Node { .. } => "Node.js",
            Self::Kotlin { .. } => "Kotlin",
            Self::Gradle { .. } => "Gradle",
            Self::Maven => "Maven",
            Self::Ruby => "Ruby",
            Self::Swift => "Swift",
            Self::Xcode { .. } => "Xcode",
            Self::Zig => "Zig",
            Self::DotNet { .. } => ".NET",
            Self::Php => "PHP",
            Self::Dart { flutter: true } => "Flutter",
            Self::Dart { flutter: false } => "Dart",
            Self::Sbt => "Scala",
            Self::Haskell { .. } => "Haskell",
            Self::Clojure { .. } => "Clojure",
            Self::Rebar => "Erlang",
            Self::Dune => "OCaml",
            Self::Perl => "Perl",
            Self::Julia => "Julia",
            Self::R { .. } => "R",
            Self::Nim => "Nim",
            Self::Crystal => "Crystal",
            Self::Vlang => "V",
            Self::Gleam => "Gleam",
            Self::Lua => "Lua",
            Self::Bazel => "Bazel",
            Self::Meson => "Meson",
            Self::CMake => "CMake",
            Self::Make => "Make",
        }
    }

    /// The file that triggered detection (e.g. "Cargo.toml", "package.json").
    pub fn detected_file(&self) -> &'static str {
        match self {
            Self::Cargo => "Cargo.toml",
            Self::Go => "go.mod",
            Self::Elixir { .. } => "mix.exs",
            Self::Python { .. } => "pyproject.toml",
            Self::Node { .. } => "package.json",
            Self::Kotlin {
                build: KotlinBuild::Gradle { .. },
            } => "build.gradle(.kts) + *.kt",
            Self::Kotlin {
                build: KotlinBuild::Maven,
            } => "pom.xml + *.kt",
            Self::Gradle { .. } => "build.gradle",
            Self::Maven => "pom.xml",
            Self::Ruby => "Gemfile",
            Self::Swift => "Package.swift",
            Self::Xcode { workspace: true } => "*.xcworkspace",
            Self::Xcode { workspace: false } => "*.xcodeproj",
            Self::Zig => "build.zig",
            Self::DotNet { sln: true } => "*.sln",
            Self::DotNet { sln: false } => "*.csproj",
            Self::Php => "composer.json",
            Self::Dart { .. } => "pubspec.yaml",
            Self::Sbt => "build.sbt",
            Self::Haskell { stack: true } => "stack.yaml",
            Self::Haskell { stack: false } => "*.cabal",
            Self::Clojure { lein: true } => "project.clj",
            Self::Clojure { lein: false } => "deps.edn",
            Self::Rebar => "rebar.config",
            Self::Dune => "dune-project",
            Self::Perl => "cpanfile",
            Self::Julia => "Project.toml",
            Self::R { renv: true } => "renv.lock",
            Self::R { renv: false } => "DESCRIPTION",
            Self::Nim => "*.nimble",
            Self::Crystal => "shard.yml",
            Self::Vlang => "v.mod",
            Self::Gleam => "gleam.toml",
            Self::Lua => "*.rockspec",
            Self::Bazel => "MODULE.bazel",
            Self::Meson => "meson.build",
            Self::CMake => "CMakeLists.txt",
            Self::Make => "Makefile",
        }
    }

    /// Directories containing build artifacts for this project type.
    pub fn artifact_dirs(&self) -> &'static [&'static str] {
        match self {
            Self::Cargo => &["target"],
            Self::Go => &[],
            Self::Elixir { .. } => &["_build", "deps"],
            Self::Python { .. } => &["__pycache__", ".pytest_cache", "build", "dist", ".venv"],
            Self::Node { .. } => &["node_modules", ".next", ".nuxt", ".turbo"],
            Self::Kotlin {
                build: KotlinBuild::Gradle { .. },
            } => &["build", ".gradle"],
            Self::Kotlin {
                build: KotlinBuild::Maven,
            } => &["target"],
            Self::Gradle { .. } => &["build", ".gradle"],
            Self::Maven => &["target"],
            Self::Ruby => &[".bundle"],
            Self::Swift => &[".build"],
            Self::Xcode { .. } => &["build", "DerivedData"],
            Self::Zig => &["zig-out", ".zig-cache"],
            Self::DotNet { .. } => &["bin", "obj"],
            Self::Php => &["vendor"],
            Self::Dart { .. } => &[".dart_tool", "build"],
            Self::Sbt => &["target", "project/target"],
            Self::Haskell { stack: true } => &[".stack-work"],
            Self::Haskell { stack: false } => &["dist-newstyle"],
            Self::Clojure { lein: true } => &["target"],
            Self::Clojure { lein: false } => &[".cpcache"],
            Self::Rebar => &["_build"],
            Self::Dune => &["_build"],
            Self::Perl => &["blib", "_build"],
            Self::Julia => &[],
            Self::R { .. } => &["renv/library", ".Rproj.user"],
            Self::Nim => &["nimcache"],
            Self::Crystal => &["lib", ".shards"],
            Self::Vlang => &[],
            Self::Gleam => &["build"],
            Self::Lua => &[],
            Self::Bazel => &["bazel-bin", "bazel-out", "bazel-testlogs"],
            Self::Meson => &["builddir"],
            Self::CMake => &["build"],
            Self::Make => &[],
        }
    }
}

// -- Detection ---------------------------------------------------------------

/// Detect the project kind from files in `dir`.
///
/// Checks language-specific files first (high confidence), then falls back
/// to generic build systems (lower confidence). Returns `None` if no
/// recognized project files are found.
#[must_use]
pub fn detect(dir: impl AsRef<Path>) -> Option<ProjectKind> {
    detect_in(dir.as_ref())
}

/// Like [`detect`], but walks up the directory tree if no project is found
/// in `dir`. Returns the detected kind and the directory it was found in.
///
/// This handles the common case of running from a subdirectory inside a
/// workspace (e.g. `tower/imp/` inside a Cargo workspace rooted at `tower/`).
#[must_use]
pub fn detect_walk(dir: impl AsRef<Path>) -> Option<(ProjectKind, PathBuf)> {
    let mut current = dir.as_ref().to_path_buf();
    loop {
        if let Some(kind) = detect_in(&current) {
            return Some((kind, current));
        }
        if !current.pop() {
            return None;
        }
    }
}

fn detect_in(dir: &Path) -> Option<ProjectKind> {
    // Language-specific build files — highest confidence
    if dir.join("Cargo.toml").exists() {
        return Some(ProjectKind::Cargo);
    }
    if dir.join("go.mod").exists() {
        return Some(ProjectKind::Go);
    }
    if dir.join("mix.exs").exists() {
        return Some(ProjectKind::Elixir {
            escript: elixir_has_escript(dir),
        });
    }

    // Python
    if dir.join("pyproject.toml").exists()
        || dir.join("setup.py").exists()
        || dir.join("setup.cfg").exists()
    {
        return Some(ProjectKind::Python {
            uv: command_on_path("uv"),
        });
    }

    // Node.js
    if dir.join("package.json").exists() {
        return Some(ProjectKind::Node {
            manager: detect_node_pm(dir),
        });
    }

    // JVM
    let has_gradle = dir.join("build.gradle").exists() || dir.join("build.gradle.kts").exists();
    let has_maven = dir.join("pom.xml").exists();
    let has_kotlin = has_kotlin_sources(dir);
    if has_gradle && has_kotlin {
        return Some(ProjectKind::Kotlin {
            build: KotlinBuild::Gradle {
                wrapper: dir.join("gradlew").exists(),
            },
        });
    }
    if has_maven && has_kotlin {
        return Some(ProjectKind::Kotlin {
            build: KotlinBuild::Maven,
        });
    }
    if has_gradle {
        return Some(ProjectKind::Gradle {
            wrapper: dir.join("gradlew").exists(),
        });
    }
    if has_maven {
        return Some(ProjectKind::Maven);
    }
    if dir.join("build.sbt").exists() {
        return Some(ProjectKind::Sbt);
    }

    // Ruby
    if dir.join("Gemfile").exists() {
        return Some(ProjectKind::Ruby);
    }

    // Swift
    if dir.join("Package.swift").exists() {
        return Some(ProjectKind::Swift);
    }

    // Xcode (Objective-C / Objective-C++ / Apple platform projects)
    {
        let has_workspace = has_extension_in_dir(dir, "xcworkspace");
        let has_project = !has_workspace && has_extension_in_dir(dir, "xcodeproj");
        if has_workspace || has_project {
            return Some(ProjectKind::Xcode {
                workspace: has_workspace,
            });
        }
    }

    // Zig
    if dir.join("build.zig").exists() {
        return Some(ProjectKind::Zig);
    }

    // .NET
    {
        let has_sln = has_extension_in_dir(dir, "sln");
        let has_csproj = !has_sln && has_extension_in_dir(dir, "csproj");
        if has_sln || has_csproj {
            return Some(ProjectKind::DotNet { sln: has_sln });
        }
    }

    // PHP
    if dir.join("composer.json").exists() {
        return Some(ProjectKind::Php);
    }

    // Dart / Flutter
    if dir.join("pubspec.yaml").exists() {
        let is_flutter = std::fs::read_to_string(dir.join("pubspec.yaml"))
            .map(|c| c.contains("flutter:"))
            .unwrap_or(false);
        return Some(ProjectKind::Dart {
            flutter: is_flutter,
        });
    }

    // Haskell (stack.yaml preferred over *.cabal)
    if dir.join("stack.yaml").exists() {
        return Some(ProjectKind::Haskell { stack: true });
    }
    if has_extension_in_dir(dir, "cabal") {
        return Some(ProjectKind::Haskell { stack: false });
    }

    // Clojure (project.clj = Leiningen, deps.edn = CLI/tools.deps)
    if dir.join("project.clj").exists() {
        return Some(ProjectKind::Clojure { lein: true });
    }
    if dir.join("deps.edn").exists() {
        return Some(ProjectKind::Clojure { lein: false });
    }

    // Erlang
    if dir.join("rebar.config").exists() {
        return Some(ProjectKind::Rebar);
    }

    // OCaml
    if dir.join("dune-project").exists() {
        return Some(ProjectKind::Dune);
    }

    // Perl (cpanfile or Makefile.PL — checked before generic Make)
    if dir.join("cpanfile").exists() || dir.join("Makefile.PL").exists() {
        return Some(ProjectKind::Perl);
    }

    // Julia
    if dir.join("Project.toml").exists() {
        return Some(ProjectKind::Julia);
    }

    // R
    if dir.join("DESCRIPTION").exists() || dir.join("renv.lock").exists() {
        return Some(ProjectKind::R {
            renv: dir.join("renv.lock").exists(),
        });
    }

    // Nim
    if has_extension_in_dir(dir, "nimble") {
        return Some(ProjectKind::Nim);
    }

    // Crystal
    if dir.join("shard.yml").exists() {
        return Some(ProjectKind::Crystal);
    }

    // V
    if dir.join("v.mod").exists() {
        return Some(ProjectKind::Vlang);
    }

    // Gleam
    if dir.join("gleam.toml").exists() {
        return Some(ProjectKind::Gleam);
    }

    // Lua (LuaRocks)
    if has_extension_in_dir(dir, "rockspec") {
        return Some(ProjectKind::Lua);
    }

    // -- Build systems (lower confidence) ------------------------------------

    // Bazel (MODULE.bazel = Bzlmod, WORKSPACE = legacy)
    // Use is_file() for WORKSPACE — a directory named WORKSPACE is common
    // (e.g. ~/WORKSPACE) and should not trigger detection.
    if dir.join("MODULE.bazel").is_file() || dir.join("WORKSPACE").is_file() {
        return Some(ProjectKind::Bazel);
    }

    if dir.join("meson.build").exists() {
        return Some(ProjectKind::Meson);
    }
    if dir.join("CMakeLists.txt").exists() {
        return Some(ProjectKind::CMake);
    }
    if dir.join("Makefile").exists()
        || dir.join("makefile").exists()
        || dir.join("GNUmakefile").exists()
    {
        return Some(ProjectKind::Make);
    }

    None
}

/// Detect the project kind, walking up from `dir` if nothing is found.
///
/// Convenience wrapper over [`detect_walk`] that returns only the kind.
#[must_use]
pub fn detect_nearest(dir: impl AsRef<Path>) -> Option<ProjectKind> {
    detect_walk(dir).map(|(kind, _)| kind)
}

/// Check whether a command exists on `$PATH`.
#[must_use]
pub fn command_on_path(name: &str) -> bool {
    Command::new("which")
        .arg(name)
        .stdout(Stdio::null())
        .stderr(Stdio::null())
        .status()
        .map(|s| s.success())
        .unwrap_or(false)
}

/// Formatted table of all supported project types for error messages.
#[must_use]
pub fn supported_table() -> String {
    let entries = [
        ("Cargo.toml", "cargo build"),
        ("go.mod", "go build ./..."),
        ("mix.exs", "mix compile"),
        ("pyproject.toml", "pip install . (or uv)"),
        ("setup.py", "pip install ."),
        ("setup.cfg", "pip install ."),
        ("package.json", "npm/yarn/pnpm/bun install"),
        ("build.gradle(.kts) + *.kt", "./gradlew build / mvn package"),
        ("build.gradle", "./gradlew build"),
        ("pom.xml", "mvn package"),
        ("build.sbt", "sbt compile"),
        ("Gemfile", "bundle install"),
        ("Package.swift", "swift build"),
        ("*.xcworkspace / *.xcodeproj", "xcodebuild build"),
        ("build.zig", "zig build"),
        ("*.csproj", "dotnet build"),
        ("composer.json", "composer install"),
        ("pubspec.yaml", "dart pub get / flutter pub get"),
        ("stack.yaml", "stack build"),
        ("*.cabal", "cabal build"),
        ("project.clj", "lein compile"),
        ("deps.edn", "clj -M:build"),
        ("rebar.config", "rebar3 compile"),
        ("dune-project", "dune build"),
        ("cpanfile", "cpanm --installdeps ."),
        ("Project.toml", "julia -e 'using Pkg; Pkg.instantiate()'"),
        ("DESCRIPTION / renv.lock", "R CMD build . / renv::restore()"),
        ("*.nimble", "nimble build"),
        ("shard.yml", "shards build"),
        ("v.mod", "v ."),
        ("gleam.toml", "gleam build"),
        ("*.rockspec", "luarocks make"),
        ("MODULE.bazel", "bazel build //..."),
        ("meson.build", "meson setup + compile"),
        ("CMakeLists.txt", "cmake -B build && cmake --build build"),
        ("Makefile", "make"),
    ];

    let mut out = String::from("  supported project files:\n");
    for (file, cmd) in entries {
        out.push_str(&format!("    {file:<18} → {cmd}\n"));
    }
    out
}

// -- Node.js package.json helpers --------------------------------------------

/// Check whether a Node project's `package.json` contains a specific script.
#[must_use]
pub fn node_has_script(dir: &Path, name: &str) -> bool {
    let Ok(content) = std::fs::read_to_string(dir.join("package.json")) else {
        return false;
    };
    let Ok(json) = serde_json::from_str::<serde_json::Value>(&content) else {
        return false;
    };
    json.get("scripts")
        .and_then(|s| s.get(name))
        .and_then(|v| v.as_str())
        .is_some_and(|s| !s.is_empty())
}

/// Check whether a Node project's `package.json` has a `"bin"` field.
#[must_use]
pub fn node_has_bin(dir: &Path) -> bool {
    let Ok(content) = std::fs::read_to_string(dir.join("package.json")) else {
        return false;
    };
    let Ok(json) = serde_json::from_str::<serde_json::Value>(&content) else {
        return false;
    };
    match json.get("bin") {
        Some(serde_json::Value::String(s)) => !s.is_empty(),
        Some(serde_json::Value::Object(m)) => !m.is_empty(),
        _ => false,
    }
}

// -- Private helpers ---------------------------------------------------------

fn elixir_has_escript(dir: &Path) -> bool {
    if let Ok(content) = std::fs::read_to_string(dir.join("mix.exs")) {
        if content.contains("escript:") {
            return true;
        }
    }
    let apps_dir = dir.join("apps");
    if apps_dir.is_dir() {
        if let Ok(entries) = std::fs::read_dir(&apps_dir) {
            for entry in entries.flatten() {
                let child_mix = entry.path().join("mix.exs");
                if let Ok(content) = std::fs::read_to_string(&child_mix) {
                    if content.contains("escript:") {
                        return true;
                    }
                }
            }
        }
    }
    false
}

fn has_extension_in_dir(dir: &Path, ext: &str) -> bool {
    std::fs::read_dir(dir)
        .ok()
        .map(|entries| {
            entries
                .flatten()
                .any(|e| e.path().extension().is_some_and(|x| x == ext))
        })
        .unwrap_or(false)
}

fn has_extension_in_tree(dir: &Path, exts: &[&str]) -> bool {
    if !dir.is_dir() {
        return false;
    }

    let mut stack = vec![dir.to_path_buf()];
    while let Some(current) = stack.pop() {
        let Ok(entries) = std::fs::read_dir(&current) else {
            continue;
        };
        for entry in entries.flatten() {
            let path = entry.path();
            if path.is_dir() {
                let skip = path
                    .file_name()
                    .and_then(|name| name.to_str())
                    .is_some_and(|name| {
                        matches!(
                            name,
                            ".git" | ".gradle" | "build" | "target" | "node_modules"
                        )
                    });
                if !skip {
                    stack.push(path);
                }
                continue;
            }

            let Some(ext) = path.extension().and_then(|ext| ext.to_str()) else {
                continue;
            };
            if exts.contains(&ext) {
                return true;
            }
        }
    }

    false
}

fn has_file_suffix_in_dir(dir: &Path, suffix: &str) -> bool {
    std::fs::read_dir(dir)
        .ok()
        .map(|entries| {
            entries.flatten().any(|entry| {
                entry
                    .file_name()
                    .to_str()
                    .is_some_and(|name| name.ends_with(suffix))
            })
        })
        .unwrap_or(false)
}

fn has_kotlin_sources(dir: &Path) -> bool {
    has_extension_in_tree(&dir.join("src"), &["kt", "kts"])
        || has_extension_in_tree(&dir.join("app"), &["kt", "kts"])
        || has_extension_in_dir(dir, "kt")
        || has_file_suffix_in_dir(dir, ".main.kts")
}

fn detect_node_pm(dir: &Path) -> NodePM {
    if dir.join("bun.lockb").exists() || dir.join("bun.lock").exists() {
        NodePM::Bun
    } else if dir.join("pnpm-lock.yaml").exists() {
        NodePM::Pnpm
    } else if dir.join("yarn.lock").exists() {
        NodePM::Yarn
    } else {
        NodePM::Npm
    }
}

// -- Workspace detection -----------------------------------------------------

/// A package in a workspace that has a "dev" script.
#[derive(Debug, Clone)]
pub struct WorkspacePackage {
    pub name: String,
    pub path: PathBuf,
    pub dev_script: String,
}

/// Detect Node.js workspace packages that have a "dev" script.
#[must_use]
pub fn detect_node_workspace(dir: &Path) -> Option<Vec<WorkspacePackage>> {
    let patterns =
        read_pnpm_workspace_patterns(dir).or_else(|| read_npm_workspace_patterns(dir))?;
    let mut packages = Vec::new();
    for pattern in &patterns {
        collect_workspace_packages(dir, pattern, &mut packages);
    }
    packages.sort_by(|a, b| a.name.cmp(&b.name));
    Some(packages)
}

fn read_pnpm_workspace_patterns(dir: &Path) -> Option<Vec<String>> {
    let content = std::fs::read_to_string(dir.join("pnpm-workspace.yaml")).ok()?;
    let mut patterns = Vec::new();
    let mut in_packages = false;
    for line in content.lines() {
        let trimmed = line.trim();
        if trimmed == "packages:" {
            in_packages = true;
            continue;
        }
        if in_packages {
            if !trimmed.starts_with('-') {
                if !trimmed.is_empty() {
                    break;
                }
                continue;
            }
            let value = trimmed
                .trim_start_matches('-')
                .trim()
                .trim_matches('"')
                .trim_matches('\'');
            if value.starts_with('!') {
                continue;
            }
            if !value.is_empty() {
                patterns.push(value.to_string());
            }
        }
    }
    if patterns.is_empty() {
        return None;
    }
    Some(patterns)
}

fn read_npm_workspace_patterns(dir: &Path) -> Option<Vec<String>> {
    let content = std::fs::read_to_string(dir.join("package.json")).ok()?;
    let json: serde_json::Value = serde_json::from_str(&content).ok()?;
    let arr = json.get("workspaces")?.as_array()?;
    let patterns: Vec<String> = arr
        .iter()
        .filter_map(|v| v.as_str())
        .filter(|s| !s.starts_with('!'))
        .map(|s| s.to_string())
        .collect();
    if patterns.is_empty() {
        return None;
    }
    Some(patterns)
}

fn collect_workspace_packages(root: &Path, pattern: &str, out: &mut Vec<WorkspacePackage>) {
    let prefix = match pattern.strip_suffix("/*") {
        Some(p) => p,
        None => pattern,
    };
    let search_dir = root.join(prefix);
    let entries = match std::fs::read_dir(&search_dir) {
        Ok(e) => e,
        Err(_) => return,
    };
    for entry in entries.flatten() {
        let pkg_dir = entry.path();
        if !pkg_dir.is_dir() {
            continue;
        }
        let pkg_json_path = pkg_dir.join("package.json");
        let content = match std::fs::read_to_string(&pkg_json_path) {
            Ok(c) => c,
            Err(_) => continue,
        };
        let json: serde_json::Value = match serde_json::from_str(&content) {
            Ok(v) => v,
            Err(_) => continue,
        };
        if let Some(dev) = json
            .get("scripts")
            .and_then(|s| s.get("dev"))
            .and_then(|d| d.as_str())
        {
            let name = pkg_dir
                .file_name()
                .map(|n| n.to_string_lossy().into_owned())
                .unwrap_or_default();
            let abs_path = match pkg_dir.canonicalize() {
                Ok(p) => p,
                Err(_) => pkg_dir,
            };
            out.push(WorkspacePackage {
                name,
                path: abs_path,
                dev_script: dev.to_string(),
            });
        }
    }
}

// -- Tests -------------------------------------------------------------------

#[cfg(test)]
mod tests {
    use super::*;
    use std::fs;
    use tempfile::tempdir;

    #[test]
    fn detect_cargo() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("Cargo.toml"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Cargo));
    }

    #[test]
    fn detect_go() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("go.mod"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Go));
    }

    #[test]
    fn detect_elixir() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("mix.exs"), "").unwrap();
        assert!(matches!(
            detect(dir.path()),
            Some(ProjectKind::Elixir { .. })
        ));
    }

    #[test]
    fn detect_python_pyproject() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("pyproject.toml"), "").unwrap();
        assert!(matches!(
            detect(dir.path()),
            Some(ProjectKind::Python { .. })
        ));
    }

    #[test]
    fn detect_python_setup_py() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("setup.py"), "").unwrap();
        assert!(matches!(
            detect(dir.path()),
            Some(ProjectKind::Python { .. })
        ));
    }

    #[test]
    fn detect_python_setup_cfg() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("setup.cfg"), "").unwrap();
        assert!(matches!(
            detect(dir.path()),
            Some(ProjectKind::Python { .. })
        ));
    }

    #[test]
    fn detect_node_npm_default() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("package.json"), "{}").unwrap();
        assert_eq!(
            detect(dir.path()),
            Some(ProjectKind::Node {
                manager: NodePM::Npm
            })
        );
    }

    #[test]
    fn detect_node_yarn() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("package.json"), "{}").unwrap();
        fs::write(dir.path().join("yarn.lock"), "").unwrap();
        assert_eq!(
            detect(dir.path()),
            Some(ProjectKind::Node {
                manager: NodePM::Yarn
            })
        );
    }

    #[test]
    fn detect_node_pnpm() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("package.json"), "{}").unwrap();
        fs::write(dir.path().join("pnpm-lock.yaml"), "").unwrap();
        assert_eq!(
            detect(dir.path()),
            Some(ProjectKind::Node {
                manager: NodePM::Pnpm
            })
        );
    }

    #[test]
    fn detect_node_bun() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("package.json"), "{}").unwrap();
        fs::write(dir.path().join("bun.lockb"), "").unwrap();
        assert_eq!(
            detect(dir.path()),
            Some(ProjectKind::Node {
                manager: NodePM::Bun
            })
        );
    }

    #[test]
    fn detect_gradle_with_wrapper() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("build.gradle"), "").unwrap();
        fs::write(dir.path().join("gradlew"), "").unwrap();
        assert_eq!(
            detect(dir.path()),
            Some(ProjectKind::Gradle { wrapper: true })
        );
    }

    #[test]
    fn detect_gradle_kts_no_wrapper() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("build.gradle.kts"), "").unwrap();
        assert_eq!(
            detect(dir.path()),
            Some(ProjectKind::Gradle { wrapper: false })
        );
    }

    #[test]
    fn detect_kotlin_gradle() {
        let dir = tempdir().unwrap();
        let src = dir.path().join("src/main/kotlin");
        fs::create_dir_all(&src).unwrap();
        fs::write(dir.path().join("build.gradle.kts"), "").unwrap();
        fs::write(dir.path().join("gradlew"), "").unwrap();
        fs::write(src.join("App.kt"), "fun main() = println(\"hi\")").unwrap();
        assert_eq!(
            detect(dir.path()),
            Some(ProjectKind::Kotlin {
                build: KotlinBuild::Gradle { wrapper: true }
            })
        );
    }

    #[test]
    fn detect_kotlin_maven() {
        let dir = tempdir().unwrap();
        let src = dir.path().join("src/main/kotlin");
        fs::create_dir_all(&src).unwrap();
        fs::write(dir.path().join("pom.xml"), "").unwrap();
        fs::write(src.join("App.kt"), "fun main() = println(\"hi\")").unwrap();
        assert_eq!(
            detect(dir.path()),
            Some(ProjectKind::Kotlin {
                build: KotlinBuild::Maven
            })
        );
    }

    #[test]
    fn detect_maven() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("pom.xml"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Maven));
    }

    #[test]
    fn detect_sbt() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("build.sbt"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Sbt));
    }

    #[test]
    fn detect_ruby() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("Gemfile"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Ruby));
    }

    #[test]
    fn detect_swift() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("Package.swift"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Swift));
    }

    #[test]
    fn detect_xcodeproj() {
        let dir = tempdir().unwrap();
        fs::create_dir(dir.path().join("MyApp.xcodeproj")).unwrap();
        assert_eq!(
            detect(dir.path()),
            Some(ProjectKind::Xcode { workspace: false })
        );
    }

    #[test]
    fn detect_xcworkspace_preferred_over_xcodeproj() {
        let dir = tempdir().unwrap();
        fs::create_dir(dir.path().join("MyApp.xcworkspace")).unwrap();
        fs::create_dir(dir.path().join("MyApp.xcodeproj")).unwrap();
        assert_eq!(
            detect(dir.path()),
            Some(ProjectKind::Xcode { workspace: true })
        );
    }

    #[test]
    fn detect_zig() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("build.zig"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Zig));
    }

    #[test]
    fn detect_dotnet_csproj() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("MyApp.csproj"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::DotNet { sln: false }));
    }

    #[test]
    fn detect_dotnet_sln() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("MyApp.sln"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::DotNet { sln: true }));
    }

    #[test]
    fn detect_dotnet_sln_preferred_over_csproj() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("MyApp.sln"), "").unwrap();
        fs::write(dir.path().join("MyApp.csproj"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::DotNet { sln: true }));
    }

    #[test]
    fn detect_php() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("composer.json"), "{}").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Php));
    }

    #[test]
    fn detect_dart() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("pubspec.yaml"), "name: myapp").unwrap();
        assert_eq!(
            detect(dir.path()),
            Some(ProjectKind::Dart { flutter: false })
        );
    }

    #[test]
    fn detect_flutter() {
        let dir = tempdir().unwrap();
        fs::write(
            dir.path().join("pubspec.yaml"),
            "name: myapp\nflutter:\n  sdk: flutter",
        )
        .unwrap();
        assert_eq!(
            detect(dir.path()),
            Some(ProjectKind::Dart { flutter: true })
        );
    }

    #[test]
    fn detect_haskell_stack() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("stack.yaml"), "").unwrap();
        assert_eq!(
            detect(dir.path()),
            Some(ProjectKind::Haskell { stack: true })
        );
    }

    #[test]
    fn detect_haskell_cabal() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("mylib.cabal"), "").unwrap();
        assert_eq!(
            detect(dir.path()),
            Some(ProjectKind::Haskell { stack: false })
        );
    }

    #[test]
    fn detect_haskell_stack_preferred_over_cabal() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("stack.yaml"), "").unwrap();
        fs::write(dir.path().join("mylib.cabal"), "").unwrap();
        assert_eq!(
            detect(dir.path()),
            Some(ProjectKind::Haskell { stack: true })
        );
    }

    #[test]
    fn detect_clojure_lein() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("project.clj"), "").unwrap();
        assert_eq!(
            detect(dir.path()),
            Some(ProjectKind::Clojure { lein: true })
        );
    }

    #[test]
    fn detect_clojure_deps() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("deps.edn"), "").unwrap();
        assert_eq!(
            detect(dir.path()),
            Some(ProjectKind::Clojure { lein: false })
        );
    }

    #[test]
    fn detect_rebar() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("rebar.config"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Rebar));
    }

    #[test]
    fn detect_dune() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("dune-project"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Dune));
    }

    #[test]
    fn detect_perl_cpanfile() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("cpanfile"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Perl));
    }

    #[test]
    fn detect_perl_makefile_pl() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("Makefile.PL"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Perl));
    }

    #[test]
    fn detect_julia() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("Project.toml"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Julia));
    }

    #[test]
    fn detect_r_description() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("DESCRIPTION"), "Package: demo").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::R { renv: false }));
    }

    #[test]
    fn detect_r_renv_lock() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("renv.lock"), "{}").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::R { renv: true }));
    }

    #[test]
    fn detect_nim() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("myapp.nimble"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Nim));
    }

    #[test]
    fn detect_crystal() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("shard.yml"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Crystal));
    }

    #[test]
    fn detect_vlang() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("v.mod"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Vlang));
    }

    #[test]
    fn detect_gleam() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("gleam.toml"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Gleam));
    }

    #[test]
    fn detect_lua() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("mylib-1.0-1.rockspec"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Lua));
    }

    #[test]
    fn detect_bazel_module() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("MODULE.bazel"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Bazel));
    }

    #[test]
    fn detect_bazel_workspace() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("WORKSPACE"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Bazel));
    }

    #[test]
    fn workspace_directory_does_not_trigger_bazel() {
        let dir = tempdir().unwrap();
        fs::create_dir(dir.path().join("WORKSPACE")).unwrap();
        assert_eq!(detect(dir.path()), None);
    }

    #[test]
    fn detect_meson() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("meson.build"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Meson));
    }

    #[test]
    fn detect_cmake() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("CMakeLists.txt"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::CMake));
    }

    #[test]
    fn detect_makefile() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("Makefile"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Make));
    }

    #[test]
    fn detect_makefile_lowercase() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("makefile"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Make));
    }

    #[test]
    fn detect_gnumakefile() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("GNUmakefile"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Make));
    }

    #[test]
    fn detect_empty_dir_returns_none() {
        let dir = tempdir().unwrap();
        assert_eq!(detect(dir.path()), None);
    }

    // -- Priority: language-specific wins over generic -----------------------

    #[test]
    fn cargo_wins_over_makefile() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("Cargo.toml"), "").unwrap();
        fs::write(dir.path().join("Makefile"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Cargo));
    }

    #[test]
    fn go_wins_over_makefile() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("go.mod"), "").unwrap();
        fs::write(dir.path().join("Makefile"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Go));
    }

    #[test]
    fn node_wins_over_cmake() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("package.json"), "{}").unwrap();
        fs::write(dir.path().join("CMakeLists.txt"), "").unwrap();
        assert_eq!(
            detect(dir.path()),
            Some(ProjectKind::Node {
                manager: NodePM::Npm
            })
        );
    }

    #[test]
    fn cargo_wins_over_node() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("Cargo.toml"), "").unwrap();
        fs::write(dir.path().join("package.json"), "{}").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Cargo));
    }

    #[test]
    fn perl_makefile_pl_does_not_trigger_make() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("Makefile.PL"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Perl));
    }

    #[test]
    fn gleam_wins_over_bazel() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("gleam.toml"), "").unwrap();
        fs::write(dir.path().join("WORKSPACE"), "").unwrap();
        assert_eq!(detect(dir.path()), Some(ProjectKind::Gleam));
    }

    #[test]
    fn kotlin_wins_over_gradle() {
        let dir = tempdir().unwrap();
        let src = dir.path().join("src/main/kotlin");
        fs::create_dir_all(&src).unwrap();
        fs::write(dir.path().join("build.gradle.kts"), "").unwrap();
        fs::write(src.join("App.kt"), "fun main() = println(\"hi\")").unwrap();
        assert_eq!(
            detect(dir.path()),
            Some(ProjectKind::Kotlin {
                build: KotlinBuild::Gradle { wrapper: false }
            })
        );
    }

    // -- artifact_dirs -------------------------------------------------------

    #[test]
    fn cargo_artifacts_include_target() {
        assert!(ProjectKind::Cargo.artifact_dirs().contains(&"target"));
    }

    #[test]
    fn swift_artifacts_include_build() {
        assert!(ProjectKind::Swift.artifact_dirs().contains(&".build"));
    }

    #[test]
    fn kotlin_gradle_artifacts_include_build() {
        let dirs = ProjectKind::Kotlin {
            build: KotlinBuild::Gradle { wrapper: false },
        }
        .artifact_dirs();
        assert!(dirs.contains(&"build"));
        assert!(dirs.contains(&".gradle"));
    }

    #[test]
    fn dotnet_artifacts_include_bin_obj() {
        let kind = ProjectKind::DotNet { sln: false };
        assert!(kind.artifact_dirs().contains(&"bin"));
        assert!(kind.artifact_dirs().contains(&"obj"));
    }

    #[test]
    fn zig_artifacts_include_zig_out() {
        let dirs = ProjectKind::Zig.artifact_dirs();
        assert!(dirs.contains(&"zig-out"));
        assert!(dirs.contains(&".zig-cache"));
    }

    #[test]
    fn node_artifacts_include_node_modules() {
        let kind = ProjectKind::Node {
            manager: NodePM::Npm,
        };
        assert!(kind.artifact_dirs().contains(&"node_modules"));
    }

    #[test]
    fn php_artifacts_include_vendor() {
        assert!(ProjectKind::Php.artifact_dirs().contains(&"vendor"));
    }

    #[test]
    fn dart_artifacts_include_dart_tool() {
        assert!(ProjectKind::Dart { flutter: false }
            .artifact_dirs()
            .contains(&".dart_tool"));
    }

    #[test]
    fn haskell_stack_artifacts() {
        assert!(ProjectKind::Haskell { stack: true }
            .artifact_dirs()
            .contains(&".stack-work"));
    }

    #[test]
    fn haskell_cabal_artifacts() {
        assert!(ProjectKind::Haskell { stack: false }
            .artifact_dirs()
            .contains(&"dist-newstyle"));
    }

    #[test]
    fn bazel_artifacts() {
        let dirs = ProjectKind::Bazel.artifact_dirs();
        assert!(dirs.contains(&"bazel-bin"));
        assert!(dirs.contains(&"bazel-out"));
    }

    #[test]
    fn r_artifacts_include_renv_library() {
        assert!(ProjectKind::R { renv: true }
            .artifact_dirs()
            .contains(&"renv/library"));
    }

    // -- Workspace detection -------------------------------------------------

    fn create_pkg(parent: &Path, name: &str, dev_script: Option<&str>) {
        let pkg = parent.join(name);
        fs::create_dir_all(&pkg).unwrap();
        let scripts = match dev_script {
            Some(s) => format!(r#", "scripts": {{ "dev": "{s}" }}"#),
            None => String::new(),
        };
        fs::write(
            pkg.join("package.json"),
            format!(r#"{{ "name": "{name}"{scripts} }}"#),
        )
        .unwrap();
    }

    #[test]
    fn detect_pnpm_workspace() {
        let dir = tempdir().unwrap();
        let root = dir.path();
        fs::write(root.join("package.json"), r#"{ "name": "root" }"#).unwrap();
        fs::write(
            root.join("pnpm-workspace.yaml"),
            "packages:\n  - \"apps/*\"\n  - \"!apps/ignored\"\n",
        )
        .unwrap();
        fs::create_dir_all(root.join("apps")).unwrap();
        create_pkg(&root.join("apps"), "web", Some("next dev"));
        create_pkg(&root.join("apps"), "api", None);
        let result = detect_node_workspace(root).unwrap();
        assert_eq!(result.len(), 1);
        assert_eq!(result[0].name, "web");
    }

    #[test]
    fn detect_npm_workspace() {
        let dir = tempdir().unwrap();
        let root = dir.path();
        fs::write(
            root.join("package.json"),
            r#"{ "name": "root", "workspaces": ["packages/*"] }"#,
        )
        .unwrap();
        fs::create_dir_all(root.join("packages")).unwrap();
        create_pkg(&root.join("packages"), "alpha", Some("vite dev"));
        create_pkg(&root.join("packages"), "beta", Some("node server.js"));
        let result = detect_node_workspace(root).unwrap();
        assert_eq!(result.len(), 2);
        assert_eq!(result[0].name, "alpha");
        assert_eq!(result[1].name, "beta");
    }

    #[test]
    fn no_workspace_returns_none() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("package.json"), r#"{ "name": "solo" }"#).unwrap();
        assert!(detect_node_workspace(dir.path()).is_none());
    }

    #[test]
    fn node_has_script_finds_build() {
        let dir = tempdir().unwrap();
        fs::write(
            dir.path().join("package.json"),
            r#"{ "scripts": { "build": "tsc", "test": "jest" } }"#,
        )
        .unwrap();
        assert!(node_has_script(dir.path(), "build"));
        assert!(node_has_script(dir.path(), "test"));
        assert!(!node_has_script(dir.path(), "lint"));
    }

    #[test]
    fn node_has_script_returns_false_when_no_scripts() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("package.json"), r#"{ "name": "foo" }"#).unwrap();
        assert!(!node_has_script(dir.path(), "build"));
    }

    #[test]
    fn node_has_script_returns_false_for_empty_script() {
        let dir = tempdir().unwrap();
        fs::write(
            dir.path().join("package.json"),
            r#"{ "scripts": { "build": "" } }"#,
        )
        .unwrap();
        assert!(!node_has_script(dir.path(), "build"));
    }

    #[test]
    fn node_has_bin_string_form() {
        let dir = tempdir().unwrap();
        fs::write(
            dir.path().join("package.json"),
            r#"{ "bin": "src/cli.js" }"#,
        )
        .unwrap();
        assert!(node_has_bin(dir.path()));
    }

    #[test]
    fn node_has_bin_object_form() {
        let dir = tempdir().unwrap();
        fs::write(
            dir.path().join("package.json"),
            r#"{ "bin": { "mycli": "src/cli.js" } }"#,
        )
        .unwrap();
        assert!(node_has_bin(dir.path()));
    }

    #[test]
    fn node_has_bin_returns_false_when_absent() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("package.json"), r#"{ "name": "foo" }"#).unwrap();
        assert!(!node_has_bin(dir.path()));
    }

    #[test]
    fn workspace_no_dev_scripts() {
        let dir = tempdir().unwrap();
        let root = dir.path();
        fs::write(
            root.join("package.json"),
            r#"{ "name": "root", "workspaces": ["libs/*"] }"#,
        )
        .unwrap();
        fs::create_dir_all(root.join("libs")).unwrap();
        create_pkg(&root.join("libs"), "utils", None);
        let result = detect_node_workspace(root).unwrap();
        assert!(result.is_empty());
    }

    // -- detect_walk ---------------------------------------------------------

    #[test]
    fn detect_walk_finds_project_in_current_dir() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("Cargo.toml"), "").unwrap();
        let (kind, found_dir) = detect_walk(dir.path()).unwrap();
        assert_eq!(kind, ProjectKind::Cargo);
        assert_eq!(found_dir, dir.path());
    }

    #[test]
    fn detect_walk_finds_project_in_parent() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("Cargo.toml"), "").unwrap();
        let child = dir.path().join("subdir");
        fs::create_dir(&child).unwrap();
        let (kind, found_dir) = detect_walk(&child).unwrap();
        assert_eq!(kind, ProjectKind::Cargo);
        assert_eq!(found_dir, dir.path().to_path_buf());
    }

    #[test]
    fn detect_walk_finds_project_in_grandparent() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("go.mod"), "").unwrap();
        let deep = dir.path().join("a").join("b").join("c");
        fs::create_dir_all(&deep).unwrap();
        let (kind, _) = detect_walk(&deep).unwrap();
        assert_eq!(kind, ProjectKind::Go);
    }

    #[test]
    fn detect_walk_prefers_closest_project() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("Cargo.toml"), "").unwrap();
        let child = dir.path().join("frontend");
        fs::create_dir(&child).unwrap();
        fs::write(child.join("package.json"), "{}").unwrap();
        let (kind, found_dir) = detect_walk(&child).unwrap();
        assert_eq!(
            kind,
            ProjectKind::Node {
                manager: NodePM::Npm
            }
        );
        assert_eq!(found_dir, child);
    }

    #[test]
    fn detect_nearest_returns_kind_only() {
        let dir = tempdir().unwrap();
        fs::write(dir.path().join("Cargo.toml"), "").unwrap();
        let child = dir.path().join("src");
        fs::create_dir(&child).unwrap();
        assert_eq!(detect_nearest(&child), Some(ProjectKind::Cargo));
    }
}