feat: add default-packages file support for fnm install

.changeset/shy-otters-install.md

@@ -0,0 +1,6 @@
+---
+"fnm": minor
+---
+
+Added support for `default-packages` file. When present at `$FNM_DIR/default-packages`, packages listed in this file are automatically installed globally after every `fnm install`. Compatible with nvm's default-packages format.
+

docs/commands.md

@@ -225,6 +225,8 @@ Options:
 ```
 Install a new Node.js version
 
+When a `default-packages` file exists at `$FNM_DIR/default-packages`, fnm will install the listed packages globally (via `npm install -g`) after each `fnm install`.
+
 Usage: fnm install [OPTIONS] [VERSION]
 
 Arguments:

docs/configuration.md

@@ -52,6 +52,14 @@ error: Can't find version in dotfiles. Please provide a version manually to the
 
 Runs [`corepack enable`](https://nodejs.org/api/corepack.html#enabling-the-feature) when a new version of Node.js is installed. Experimental due to the fact Corepack itself is experimental.
 
+### `default-packages` file
+
+When present at `$FNM_DIR/default-packages`, fnm will automatically install packages listed in this file globally after every `fnm install` by running `npm install -g`. You can run `fnm env` to see the value of `$FNM_DIR` on your system.
+
+The file format is one package spec per line (supports `@version`), and lines starting with `#` are ignored.
+
+This is compatible with nvm's `default-packages` format.
+
 ### `--resolve-engines`
 
 **🧪 Experimental**

e2e/__snapshots__/default-packages.test.ts.snap

@@ -0,0 +1,27 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`Bash installs default packages: Bash 1`] = `
+"set -e
+eval "$(fnm env)"
+fnm install 18
+(fnm exec --using=18 npm list -g --depth=0) | grep 'fnm-default-packages-test' || (echo "Expected output to contain 'fnm-default-packages-test'" && exit 1)"
+`;
+
+exports[`Bash missing default-packages file does not error: Bash 1`] = `
+"set -e
+eval "$(fnm env)"
+fnm install 18"
+`;
+
+exports[`PowerShell installs default packages: PowerShell 1`] = `
+"$ErrorActionPreference = "Stop"
+fnm env | Out-String | Invoke-Expression
+fnm install 18
+$($__out__ = $(fnm exec --using=18 npm list -g --depth=0 | Select-String 'fnm-default-packages-test'); if ($__out__ -eq $null) { exit 1 } else { $__out__ })"
+`;
+
+exports[`PowerShell missing default-packages file does not error: PowerShell 1`] = `
+"$ErrorActionPreference = "Stop"
+fnm env | Out-String | Invoke-Expression
+fnm install 18"
+`;

e2e/default-packages.test.ts

@@ -0,0 +1,56 @@
+import fs from "fs"
+import path from "path"
+import { script } from "./shellcode/script.js"
+import { Bash, PowerShell } from "./shellcode/shells.js"
+import describe from "./describe.js"
+import testTmpDir from "./shellcode/test-tmp-dir.js"
+
+for (const shell of [Bash, PowerShell]) {
+  describe(shell, () => {
+    test(`installs default packages`, async () => {
+      const fnmDir = path.join(testTmpDir(), "fnm")
+      fs.mkdirSync(fnmDir, { recursive: true })
+      const pkgDir = path.join(testTmpDir(), "default-packages-pkg")
+      fs.mkdirSync(pkgDir, { recursive: true })
+      fs.writeFileSync(
+        path.join(pkgDir, "package.json"),
+        JSON.stringify(
+          {
+            name: "fnm-default-packages-test",
+            version: "1.0.0",
+          },
+          null,
+          2
+        )
+      )
+      fs.writeFileSync(path.join(fnmDir, "default-packages"), `${pkgDir}\n`)
+
+      await script(shell)
+        .then(shell.env({}))
+        .then(shell.call("fnm", ["install", "18"]))
+        .then(
+          shell.scriptOutputContains(
+            shell.call("fnm", [
+              "exec",
+              "--using=18",
+              "npm",
+              "list",
+              "-g",
+              "--depth=0",
+            ]),
+            "'fnm-default-packages-test'"
+          )
+        )
+        .takeSnapshot(shell)
+        .execute(shell)
+    })
+
+    test(`missing default-packages file does not error`, async () => {
+      await script(shell)
+        .then(shell.env({}))
+        .then(shell.call("fnm", ["install", "18"]))
+        .takeSnapshot(shell)
+        .execute(shell)
+    })
+  })
+}

src/cli.rs

@@ -14,6 +14,10 @@ pub enum SubCommand {
     LsLocal(commands::ls_local::LsLocal),
 
     /// Install a new Node.js version
+    ///
+    /// When a `default-packages` file exists at `$FNM_DIR/default-packages`,
+    /// fnm will install the listed packages globally (via `npm install -g`)
+    /// after each `fnm install`.
     #[clap(name = "install", bin_name = "install", visible_aliases = &["i"])]
     Install(commands::install::Install),
 

src/commands/install.rs

@@ -172,6 +172,8 @@ impl Command for Install {
             enable_corepack(&version, config)?;
         }
 
+        install_default_packages(&version, config)?;
+
         if use_installed {
             use_installed_version(&version, config)?;
         }
@@ -199,12 +201,84 @@ fn enable_corepack(version: &Version, config: &FnmConfig) -> Result<(), Error> {
     } else {
         corepack_path.join("bin").join("corepack")
     };
-    super::exec::Exec::new_for_version(version, corepack_path.to_str().unwrap(), &["enable"])
+    let corepack_path_str = corepack_path.to_string_lossy();
+    super::exec::Exec::new_for_version(version, &corepack_path_str, &["enable"])
         .apply(config)
         .map_err(|source| Error::CorepackError { source })?;
     Ok(())
 }
 
+fn parse_default_packages_file(file_path: &std::path::Path) -> Result<Vec<String>, std::io::Error> {
+    let contents = match std::fs::read_to_string(file_path) {
+        Ok(contents) => contents,
+        Err(err) if err.kind() == std::io::ErrorKind::NotFound => return Ok(vec![]),
+        Err(err) => return Err(err),
+    };
+
+    Ok(contents
+        .lines()
+        .filter_map(|line| {
+            let trimmed = line.trim();
+            if trimmed.is_empty() || trimmed.starts_with('#') {
+                None
+            } else {
+                Some(trimmed.to_string())
+            }
+        })
+        .collect())
+}
+
+fn install_default_packages(version: &Version, config: &FnmConfig) -> Result<(), Error> {
+    use std::process::{Command as StdCommand, Stdio};
+
+    let packages = parse_default_packages_file(&config.default_packages_file())?;
+    if packages.is_empty() {
+        return Ok(());
+    }
+
+    let npm_path = if cfg!(windows) {
+        version.installation_path(config).join("npm.cmd")
+    } else {
+        version.installation_path(config).join("bin").join("npm")
+    };
+
+    let bin_path = if cfg!(windows) {
+        version.installation_path(config)
+    } else {
+        version.installation_path(config).join("bin")
+    };
+
+    let path_env = {
+        let mut paths: Vec<_> = std::env::var_os("PATH")
+            .map(|paths_env| std::env::split_paths(&paths_env).collect())
+            .unwrap_or_default();
+        paths.insert(0, bin_path);
+        std::env::join_paths(paths).map_err(|source| Error::DefaultPackagesError {
+            source: Box::new(source),
+        })?
+    };
+
+    let status = StdCommand::new(&npm_path)
+        .args(["install", "--global"])
+        .args(&packages)
+        .stdin(Stdio::inherit())
+        .stdout(Stdio::inherit())
+        .stderr(Stdio::inherit())
+        .env("PATH", path_env)
+        .status()
+        .map_err(|source| Error::DefaultPackagesError {
+            source: Box::new(source),
+        })?;
+
+    if !status.success() {
+        return Err(Error::DefaultPackagesError {
+            source: std::io::Error::other(format!("npm install exited with {status:?}")).into(),
+        });
+    }
+
+    Ok(())
+}
+
 fn use_installed_version(version: &Version, config: &FnmConfig) -> Result<(), Error> {
     Use {
         version: Some(UserVersionReader::Direct(UserVersion::Full(
@@ -235,6 +309,11 @@ pub enum Error {
         #[from]
         source: super::exec::Error,
     },
+    #[error("Can't install default packages: {source}")]
+    DefaultPackagesError {
+        #[source]
+        source: Box<dyn std::error::Error>,
+    },
     #[error(transparent)]
     UseError {
         source: Box<<Use as Command>::Error>,
@@ -320,4 +399,40 @@ mod tests {
             .unwrap()
             .exists());
     }
+
+    #[test]
+    fn test_parse_default_packages_file() {
+        let base_dir = tempfile::tempdir().unwrap();
+        let file_path = base_dir.path().join("default-packages");
+        std::fs::write(
+            &file_path,
+            r"
+# this is a comment
+
+typescript
+prettier@3
+@scope/name
+",
+        )
+        .unwrap();
+
+        let packages = parse_default_packages_file(&file_path).unwrap();
+        assert_eq!(
+            packages,
+            vec![
+                "typescript".to_string(),
+                "prettier@3".to_string(),
+                "@scope/name".to_string(),
+            ]
+        );
+    }
+
+    #[test]
+    fn test_parse_default_packages_file_missing() {
+        let base_dir = tempfile::tempdir().unwrap();
+        let file_path = base_dir.path().join("default-packages");
+
+        let packages = parse_default_packages_file(&file_path).unwrap();
+        assert_eq!(packages, Vec::<String>::new());
+    }
 }

src/config.rs

@@ -164,6 +164,10 @@ impl FnmConfig {
             .ensure_exists_silently()
     }
 
+    pub fn default_packages_file(&self) -> std::path::PathBuf {
+        self.base_dir_with_default().join("default-packages")
+    }
+
     pub fn multishell_storage(&self) -> std::path::PathBuf {
         self.directories.multishell_storage()
     }