Add `fnm exec` to run commands with the fnm environment (#194)

Adds `fnm exec` to run a shell executable with the current node version (or a custom one provided):

```
fnm exec -- node -v # will print the current Node version in fnm
fnm exec --using 12 -- node -v # will print the version of the latest node 12 installed
fnm exec --using-file -- node -v # will print the version of the current directory's node version (based on `.nvmrc` or `.node-version`)
```

executable/Exec.re

@@ -0,0 +1,93 @@
+open Fnm;
+
+exception System_Version_Not_Supported;
+exception Ambiguous_Arguments;
+
+let startsWith = (~prefix, str) =>
+  Base.String.prefix(str, String.length(prefix)) != prefix;
+
+let unsafeRun = (~cmd, ~version as maybeVersion, ~useFileVersion) => {
+  let%lwt version =
+    switch (maybeVersion, useFileVersion) {
+    | (None, false) => Lwt.return_none
+    | (Some(_), true) => Lwt.fail(Ambiguous_Arguments)
+    | (None, true) => Fnm.Dotfiles.getVersion() |> Lwt.map(x => Some(x))
+    | (Some(version), false) => Lwt.return_some(version)
+    };
+  let%lwt currentVersion =
+    switch (version) {
+    | None => Lwt.return(Directories.currentVersion)
+    | Some(version) =>
+      let%lwt matchingVersion = LocalVersionResolver.getVersion(version);
+      let matchingVersionPath =
+        switch (matchingVersion) {
+        | Alias(path) => Versions.Aliases.toDirectory(path)
+        | Local(path) => Versions.Local.toDirectory(path)
+        | System => raise(System_Version_Not_Supported)
+        };
+      Lwt.return(matchingVersionPath);
+    };
+  let fnmPath = Filename.concat(currentVersion, "bin");
+  let path = Opt.(Sys.getenv_opt("PATH") or "");
+  let pathEnv = Printf.sprintf("PATH=%s:%s", fnmPath, path);
+  let cmd = cmd |> Array.copy |> Array.append([|"env", pathEnv|]);
+  let%lwt exitCode =
+    Lwt_process.exec(
+      ~stdin=`Keep,
+      ~stdout=`Keep,
+      ~stderr=`Keep,
+      ~env=Unix.environment(),
+      ("", cmd),
+    );
+
+  switch (exitCode) {
+  | Unix.WEXITED(0) => Lwt.return_ok()
+  | Unix.WEXITED(x)
+  | Unix.WSTOPPED(x)
+  | Unix.WSIGNALED(x) => Lwt.return_error(x)
+  };
+};
+
+let run = (~cmd, ~version, ~useFileVersion) => {
+  try%lwt(unsafeRun(~cmd, ~version, ~useFileVersion)) {
+  | Ambiguous_Arguments =>
+    Console.error(
+      <Pastel color=Pastel.Red>
+        <Pastel bold=true> "Error: " </Pastel>
+        "You passed both "
+        <Pastel color=Pastel.Cyan> "--using" </Pastel>
+        " and "
+        <Pastel color=Pastel.Cyan> "--using-file" </Pastel>
+        ".\n"
+        "Please provide only one of them."
+      </Pastel>,
+    );
+    Lwt.return_error(1);
+  | System_Version_Not_Supported =>
+    Console.error(
+      <Pastel color=Pastel.Red>
+        <Pastel bold=true> "Error: " </Pastel>
+        "System version is not supported in "
+        <Pastel color=Pastel.Yellow> "`fnm exec`" </Pastel>
+      </Pastel>,
+    );
+    Lwt.return_error(1);
+  | LocalVersionResolver.Version_Not_Installed(versionName) =>
+    Console.error(
+      <Pastel color=Pastel.Red>
+        <Pastel bold=true> "Error: " </Pastel>
+        "Version "
+        <Pastel color=Pastel.Cyan> versionName </Pastel>
+        " is not installed."
+      </Pastel>,
+    );
+    Lwt.return_error(1);
+  | Dotfiles.Version_Not_Provided =>
+    Console.error(
+      <Pastel color=Pastel.Red>
+        "No .nvmrc or .node-version file was found in the current directory. Please provide a version number."
+      </Pastel>,
+    );
+    Lwt.return_error(1);
+  };
+};

executable/FnmApp.re

@@ -11,6 +11,8 @@ let runCmd = lwt => {
 };
 
 module Commands = {
+  let exec = (version, useFileVersion, cmd) =>
+    Exec.run(~cmd=Array.of_list(cmd), ~version, ~useFileVersion) |> runCmd;
   let use = (version, quiet) => Use.run(~version, ~quiet) |> runCmd;
   let alias = (version, name) => Alias.run(~name, ~version) |> runCmd;
   let default = version => Alias.run(~name="default", ~version) |> runCmd;
@@ -233,6 +235,40 @@ let alias = {
   );
 };
 
+let exec = {
+  let doc = "Execute a binary with the current Node.js in the PATH";
+  let man = help_secs;
+  let sdocs = Manpage.s_common_options;
+
+  let usingVersion = {
+    let doc = "Use a specific $(docv)";
+    Arg.(value & opt(some(string), None) & info(["using"], ~doc));
+  };
+
+  let usingFileVersion = {
+    let doc = "Use a version from a version file";
+    Arg.(value & flag & info(["using-file"], ~doc));
+  };
+
+  let command = {
+    let doc = "The $(docv) to execute";
+    Arg.(non_empty & pos_all(string, []) & info([], ~docv="COMMAND", ~doc));
+  };
+
+  (
+    Term.(const(Commands.exec) $ usingVersion $ usingFileVersion $ command),
+    Term.info(
+      "exec",
+      ~envs,
+      ~version,
+      ~doc,
+      ~exits=Term.default_exits,
+      ~man,
+      ~sdocs,
+    ),
+  );
+};
+
 let default = {
   let doc = "Alias a version as default";
   let man = help_secs;
@@ -378,7 +414,17 @@ let argv =
 let _ =
   Term.eval_choice(
     defaultCmd,
-    [install, uninstall, use, alias, default, listLocal, listRemote, env],
+    [
+      install,
+      uninstall,
+      use,
+      alias,
+      default,
+      listLocal,
+      listRemote,
+      env,
+      exec,
+    ],
     ~argv,
   )
   |> Term.exit;

executable/Uninstall.re

@@ -2,17 +2,8 @@ open Fnm;
 open Lwt.Infix;
 
 let run = (~version) => {
-  let%lwt installedVersions = Versions.getInstalledVersions();
-
-  let formattedVersionName = Versions.format(version);
-  let matchingLocalVersions =
-    installedVersions
-    |> Versions.(
-         List.filter(v =>
-           isVersionFitsPrefix(formattedVersionName, Local.(v.name))
-           || v.name == formattedVersionName
-         )
-       );
+  let%lwt matchingLocalVersions =
+    LocalVersionResolver.getMatchingLocalVersions(version);
 
   switch (matchingLocalVersions) {
   | [] =>

executable/Use.re

@@ -2,8 +2,6 @@ open Fnm;
 
 let lwtIgnore = lwt => Lwt.catch(() => lwt, _ => Lwt.return());
 
-exception Version_Not_Installed(string);
-
 let info = (~quiet, arg) =>
   if (!quiet) {
     Logger.info(arg);
@@ -19,26 +17,10 @@ let error = (~quiet, arg) =>
     Logger.error(arg);
   };
 
-let getVersion = version => {
-  let%lwt parsed = Versions.parse(version);
-  let%lwt resultWithLts =
-    switch (parsed) {
-    | Ok(x) => Lwt.return_ok(x)
-    | Error("latest-*") =>
-      switch%lwt (VersionListingLts.getLatest()) {
-      | Error(_) => Lwt.return_error(Version_Not_Installed(version))
-      | Ok({VersionListingLts.lts, _}) =>
-        Versions.Alias("latest-" ++ lts) |> Lwt.return_ok
-      }
-    | _ => Version_Not_Installed(version) |> Lwt.return_error
-    };
-  resultWithLts |> Result.fold(Lwt.fail, Lwt.return);
-};
-
 let switchVersion = (~version, ~quiet) => {
   let info = info(~quiet);
   let debug = debug(~quiet);
-  let%lwt parsedVersion = getVersion(version);
+  let%lwt parsedVersion = LocalVersionResolver.getVersion(version);
 
   let%lwt versionPath =
     switch (parsedVersion) {
@@ -120,7 +102,7 @@ let rec askIfInstall = (~version, ~quiet, retry) => {
 
 let rec run = (~version, ~quiet) =>
   try%lwt(main(~version, ~quiet)) {
-  | Version_Not_Installed(versionString) =>
+  | LocalVersionResolver.Version_Not_Installed(versionString) =>
     error(
       ~quiet,
       <Pastel color=Pastel.Red>

feature_tests/exec/run.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+set -e
+
+fnm install v6.10.0
+fnm install v8.10.0
+fnm install v10.10.0
+fnm use v8.10.0
+
+fnm exec -- node -v | grep "v8.10.0"
+fnm exec --using 6 -- node -v | grep "v6.10.0"
+fnm exec --using 10 -- node -v | grep "v10.10.0"

library/LocalVersionResolver.re

@@ -0,0 +1,38 @@
+exception Version_Not_Installed(string);
+
+/** Parse a local version, including lts and aliases */
+let getVersion = version => {
+  let%lwt parsed = Versions.parse(version);
+  let%lwt resultWithLts =
+    switch (parsed) {
+    | Ok(x) => Lwt.return_ok(x)
+    | Error("latest-*") =>
+      switch%lwt (VersionListingLts.getLatest()) {
+      | Error(_) => Lwt.return_error(Version_Not_Installed(version))
+      | Ok({VersionListingLts.lts, _}) =>
+        Versions.Alias("latest-" ++ lts) |> Lwt.return_ok
+      }
+    | _ => Version_Not_Installed(version) |> Lwt.return_error
+    };
+  resultWithLts |> Result.fold(Lwt.fail, Lwt.return);
+};
+
+/**
+ * Get matches for all versions that match a semver partial
+ */
+let getMatchingLocalVersions = version => {
+  open Versions.Local;
+
+  let%lwt installedVersions = Versions.getInstalledVersions();
+  let formattedVersionName = Versions.format(version);
+
+  let matchingVersions =
+    installedVersions
+    |> List.filter(v =>
+         Versions.isVersionFitsPrefix(formattedVersionName, v.name)
+         || v.name == formattedVersionName
+       )
+    |> List.sort((a, b) => - compare(a.name, b.name));
+
+  Lwt.return(matchingVersions);
+};

test/TestFramework.re

@@ -21,6 +21,7 @@ let run = args => {
     Unix.environment()
     |> Array.append([|
          Printf.sprintf("%s=%s", Fnm.Config.FNM_DIR.name, tmpDir),
+         "FORCE_COLOR=false",
        |]);
   let result =
     Lwt_process.pread_chars(~env, ("", arguments)) |> Lwt_stream.to_string;

test/TestListRemote.re

@@ -57,14 +57,14 @@ let allVersions6_11 = [
   "v6.11.5",
 ];
 
-describe("List Remote", ({test}) => {
-  let versionRegExp = Str.regexp(".*[0-9]+\.[0-9]+\.[0-9]+\|.*latest-*");
+describe("List Remote", ({test, _}) => {
+  let versionRegExp = Str.regexp(".*[0-9]+\\.[0-9]+\\.[0-9]+\\|.*latest-*");
 
   let filterVersionNumbers = response =>
     response
     |> String.split_on_char('\n')
     |> List.filter(s => Str.string_match(versionRegExp, s, 0))
-    |> List.map(s => Str.replace_first(Str.regexp("\*"), "", s))
+    |> List.map(s => Str.replace_first(Str.regexp("\\*"), "", s))
     |> List.map(String.trim);
 
   let runAndFilterVersionNumbers = args => run(args) |> filterVersionNumbers;

test/TestUninstall.re

@@ -8,7 +8,7 @@ let isVersionInstalled = version =>
   |> String.split_on_char('\n')
   |> List.exists(v => v == "* v" ++ version);
 
-describe("Uninstall", ({test}) => {
+describe("Uninstall", ({test, _}) => {
   test("Should be possible to uninstall a specific version", ({expect, _}) => {
     let version = "6.0.0";
     let _ = installVersion(version);
@@ -29,9 +29,9 @@ describe("Uninstall", ({test}) => {
       uninstallVersion("6")
       |> String.split_on_char('\n')
       |> String.concat(" ");
-    expect.string(response).toMatch(
-      ".*multiple versions.*" ++ v1 ++ ".*" ++ v2 ++ ".*",
-    );
+    expect.string(response).toMatch("multiple versions");
+    expect.string(response).toMatch(" v" ++ v1 ++ " ");
+    expect.string(response).toMatch(" v" ++ v2 ++ " ");
     expect.bool(isVersionInstalled(v1)).toBeTrue();
     expect.bool(isVersionInstalled(v2)).toBeTrue();
     clearTmpDir();