Clean multishell on shell exit

this commit introduces this feature for Bash, let's see how to support other shells

e2e/__snapshots__/env.test.ts.snap

@@ -1,17 +1,40 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`Bash deletes the multishell upon shell exit: Bash 1`] = `
+"set -e
+eval "$(fnm env --delete-on-exit)"
+echo $FNM_MULTISHELL_PATH > multishell_path"
+`;
+
 exports[`Bash outputs json: Bash 1`] = `
 "set -e
 fnm env --json > file.json"
 `;
 
+exports[`Fish deletes the multishell upon shell exit: Fish 1`] = `
+"fnm env --delete-on-exit | source
+echo $FNM_MULTISHELL_PATH > multishell_path"
+`;
+
 exports[`Fish outputs json: Fish 1`] = `"fnm env --json > file.json"`;
 
+exports[`PowerShell deletes the multishell upon shell exit: PowerShell 1`] = `
+"$ErrorActionPreference = "Stop"
+fnm env --delete-on-exit | Out-String | Invoke-Expression
+echo $env:FNM_MULTISHELL_PATH | Out-File multishell_path -Encoding UTF8"
+`;
+
 exports[`PowerShell outputs json: PowerShell 1`] = `
 "$ErrorActionPreference = "Stop"
 fnm env --json | Out-File file.json -Encoding UTF8"
 `;
 
+exports[`Zsh deletes the multishell upon shell exit: Zsh 1`] = `
+"set -e
+eval "$(fnm env --delete-on-exit)"
+echo $FNM_MULTISHELL_PATH > multishell_path"
+`;
+
 exports[`Zsh outputs json: Zsh 1`] = `
 "set -e
 fnm env --json > file.json"

e2e/env.test.ts

@@ -1,4 +1,4 @@
-import { readFile } from "node:fs/promises"
+import { lstat, readFile, realpath } from "node:fs/promises"
 import { join } from "node:path"
 import { script } from "./shellcode/script.js"
 import { Bash, Fish, PowerShell, WinCmd, Zsh } from "./shellcode/shells.js"
@@ -20,7 +20,8 @@ for (const shell of [Bash, Zsh, Fish, PowerShell, WinCmd]) {
 
       if (shell.currentlySupported()) {
         const file = await readFile(join(testCwd(), filename), "utf8")
-        expect(JSON.parse(file)).toEqual({
+        const json = JSON.parse(file)
+        expect(json).toEqual({
           FNM_ARCH: expect.any(String),
           FNM_DIR: expect.any(String),
           FNM_LOGLEVEL: "info",
@@ -30,5 +31,29 @@ for (const shell of [Bash, Zsh, Fish, PowerShell, WinCmd]) {
         })
       }
     })
+
+    test(`deletes the multishell upon shell exit`, async () => {
+      const filename = `multishell_path`
+      await script(shell)
+        .then(shell.env({ args: ["--delete-on-exit"] }))
+        .then(
+          shell.redirectOutput(
+            shell.call("echo", [shell.getEnvVar("FNM_MULTISHELL_PATH")]),
+            { output: filename }
+          )
+        )
+        .takeSnapshot(shell)
+        .execute(shell)
+
+      if (shell.currentlySupported()) {
+        const multishell = await readFile(
+          join(testCwd(), filename),
+          "utf8"
+        ).then((x) => x.trim())
+        await expect(lstat(multishell)).rejects.toThrowError(
+          /no such file or directory/
+        )
+      }
+    })
   })
 }

e2e/shellcode/shells.ts

@@ -1,6 +1,7 @@
 import { cmdCall } from "./shells/cmdCall.js"
 import { cmdEnv } from "./shells/cmdEnv.js"
 import { cmdExpectCommandOutput } from "./shells/expect-command-output.js"
+import { getEnvVar } from "./shells/get-env-var.js"
 import { cmdHasOutputContains } from "./shells/output-contains.js"
 import { redirectOutput } from "./shells/redirect-output.js"
 import { cmdInSubShell } from "./shells/sub-shell.js"
@@ -21,6 +22,7 @@ export const Bash = {
   ...cmdExpectCommandOutput.bash,
   ...cmdHasOutputContains.bash,
   ...cmdInSubShell.bash,
+  ...getEnvVar.posix,
 }
 
 export const Zsh = {
@@ -38,6 +40,7 @@ export const Zsh = {
   ...cmdExpectCommandOutput.bash,
   ...cmdHasOutputContains.bash,
   ...cmdInSubShell.zsh,
+  ...getEnvVar.posix,
 }
 
 export const Fish = {
@@ -55,6 +58,7 @@ export const Fish = {
   ...cmdExpectCommandOutput.fish,
   ...cmdHasOutputContains.fish,
   ...cmdInSubShell.fish,
+  ...getEnvVar.posix,
 }
 
 export const PowerShell = {
@@ -73,6 +77,7 @@ export const PowerShell = {
   ...cmdExpectCommandOutput.powershell,
   ...cmdHasOutputContains.powershell,
   ...cmdInSubShell.powershell,
+  ...getEnvVar.powershell,
 }
 
 export const WinCmd = {
@@ -94,4 +99,5 @@ export const WinCmd = {
   ...cmdCall.all,
   ...cmdExpectCommandOutput.wincmd,
   ...redirectOutput.bash,
+  ...getEnvVar.winCmd,
 }

e2e/shellcode/shells/cmdEnv.ts

@@ -1,14 +1,14 @@
 import { ScriptLine, define } from "./types.js"
 
-type EnvConfig = { useOnCd: boolean; logLevel: string }
+type EnvConfig = { useOnCd: boolean; logLevel: string; args: string[] }
 export type HasEnv = { env(cfg: Partial<EnvConfig>): ScriptLine }
 
-function stringify(envConfig: Partial<EnvConfig> = {}) {
-  const { useOnCd, logLevel } = envConfig
+function stringify(config: Partial<EnvConfig> = {}) {
   return [
     `fnm env`,
-    useOnCd && "--use-on-cd",
-    logLevel && `--log-level=${logLevel}`,
+    config.useOnCd && "--use-on-cd",
+    config.logLevel && `--log-level=${config.logLevel}`,
+    ...(config.args ?? []),
   ]
     .filter(Boolean)
     .join(" ")

e2e/shellcode/shells/get-env-var.ts

@@ -0,0 +1,17 @@
+import { define } from "./types.js"
+
+export type HasGetEnvVar = {
+  getEnvVar(name: string): string
+}
+
+export const getEnvVar = {
+  posix: define<HasGetEnvVar>({
+    getEnvVar: (name) => `$${name}`,
+  }),
+  powershell: define<HasGetEnvVar>({
+    getEnvVar: (name) => `$env:${name}`,
+  }),
+  winCmd: define<HasGetEnvVar>({
+    getEnvVar: (name) => `%${name}%`,
+  }),
+}

jest.config.cjs

@@ -4,6 +4,7 @@ module.exports = {
   testEnvironment: "node",
   testTimeout: 120000,
   extensionsToTreatAsEsm: [".ts"],
+  testPathIgnorePatterns: ["<rootDir>/target/", "<rootDir>/node_modules/"],
   moduleNameMapper: {
     "^(\\.{1,2}/.*)\\.js$": "$1",
     "#ansi-styles": "ansi-styles/index.js",

src/commands/env.rs

@@ -25,6 +25,10 @@ pub struct Env {
     /// Print the script to change Node versions every directory change
     #[clap(long)]
     use_on_cd: bool,
+
+    /// EXPERIMENTAL: delete the multishell on shell exit
+    #[clap(long)]
+    delete_on_exit: bool,
 }
 
 fn generate_symlink_path() -> String {
@@ -117,6 +121,12 @@ impl Command for Env {
             println!("{}", v);
         }
 
+        if self.delete_on_exit {
+            if let Some(v) = shell.delete_on_exit(&multishell_path) {
+                println!("{}", v);
+            }
+        }
+
         Ok(())
     }
 }

src/shell/bash.rs

@@ -51,4 +51,38 @@ impl Shell for Bash {
             autoload_hook = autoload_hook
         ))
     }
+
+    fn delete_on_exit(&self, fnm_multishell: &Path) -> Option<String> {
+        Some(indoc::formatdoc!(
+            r#"
+    # appends a command to a trap
+    #
+    # - 1st arg:  code to add
+    # - remaining args:  names of traps to modify
+    #
+    trap_add() {{
+        trap_add_cmd=$1; shift || fatal "${{FUNCNAME}} usage error"
+        for trap_add_name in "$@"; do
+            trap -- "$(
+                # helper fn to get existing trap command from output
+                # of trap -p
+                extract_trap_cmd() {{ printf '%s\n' "$3"; }}
+                # print existing trap command with newline
+                eval "extract_trap_cmd $(trap -p "${{trap_add_name}}")"
+                # print the new trap command
+                printf '%s\n' "${{trap_add_cmd}}"
+            )" "${{trap_add_name}}" \
+                || fatal "unable to add to trap ${{trap_add_name}}"
+        done
+    }}
+    # set the trace attribute for the above function.  this is
+    # required to modify DEBUG or RETURN traps because functions don't
+    # inherit them unless the trace attribute is set
+    declare -f -t trap_add
+
+    trap_add 'echo hi; rm "{fnm_multishell}"' EXIT
+            "#,
+            fnm_multishell = fnm_multishell.display()
+        ))
+    }
 }

src/shell/shell.rs

@@ -9,6 +9,9 @@ pub trait Shell: Debug {
         None
     }
     fn to_clap_shell(&self) -> clap_complete::Shell;
+    fn delete_on_exit(&self, _fnm_multishell: &Path) -> Option<String> {
+        None
+    }
 }
 
 #[cfg(windows)]