refactor: npx replacement

Closes #224.

lib/autofix.js

@@ -3,7 +3,6 @@ const path = require('node:path');
 const chalk = require('chalk');
 const prompts = require('prompts');
 const spawn = require('cross-spawn');
-const getPathKey = require('path-key');
 const FS = require('./fs-wrapper');
 const AppState = require('./state');
 const ErrorMessage = require('./error-message');
@@ -12,6 +11,7 @@ const StyledMessage = require('./styled-message');
 const {startReview} = require('./run-review');
 const ProjectDependencies = require('./project-dependencies');
 const exit = require('../vendor/exit');
+const {backwardsCompatiblePath, pathKey} = require('./npx');
 
 /**
  * @import {App, AutofixRequest} from "./types/app"
@@ -190,7 +190,7 @@ function formatFileContent(options, file, filePath) {
       input: file.source,
       env: hasElmFormatPathFlag
         ? process.env
-        : backwardsCompatibleElmFormatEnv()
+        : {...process.env, [pathKey]: backwardsCompatiblePath()}
     }
   );
 
@@ -237,61 +237,3 @@ ${result.stderr.toString()}`,
     source: fs.readFileSync(filePath, 'utf8')
   };
 }
-
-// When `--elm-format-path` was _not_ provided, we used to execute
-// `elm-format` like this:
-//
-// 1. Try `npx elm-format`
-// 2. Try `elm-format`
-//
-// Just starting `npx` takes 200 ms though. Luckily `npx` isn’t even
-// necessary, because the common ways of running `elm-review` are:
-//
-// 1. Install everything globally and run just `elm-review`.
-// 2. Install everything locally and run `npx elm-review`.
-// 3. Use the `--elm-format-path`.
-//
-// That’s also the only supported ways we have for the `elm` binary – there we
-// have never tried to execute `npx elm`.
-//
-// `npx` adds all potential `node_modules/.bin` up to current directory to the
-// beginning of PATH, for example:
-//
-//     ❯ npx node -p 'process.env.PATH.split(require("path").delimiter)'
-//     [
-//       '/Users/you/stuff/node_modules/.bin',
-//       '/Users/you/node_modules/.bin',
-//       '/Users/node_modules/.bin',
-//       '/node_modules/.bin',
-//       '/usr/bin',
-//       'etc'
-//     ]
-//
-// So if a user runs `npx elm-review`, when we later try to spawn just
-// `elm-format`, it’ll be found since when spawning we inherit the same PATH.
-//
-// The `npx elm-format` approach has been removed to avoid those unnessary 200 ms,
-// but to stay backwards compatible we prepend the same paths to the beginning
-// of PATH just like `npx` would (see above). This is needed when:
-//
-// - Executing `elm-review` _without_ `npx`.
-// - And expecting a _local_ `elm-format` to be used. That’s an odd use case,
-//   but was supported due to the `npx` approach.
-//
-// This can be removed in a major version.
-function backwardsCompatibleElmFormatEnv() {
-  const pathKey = getPathKey();
-  return {
-    ...process.env,
-    [pathKey]: [
-      ...process
-        .cwd()
-        .split(path.sep)
-        .map((_, index, parts) =>
-          [...parts.slice(0, index + 1), 'node_modules', '.bin'].join(path.sep)
-        )
-        .reverse(),
-      process.env[pathKey]
-    ].join(path.delimiter)
-  };
-}

lib/elm-binary.js

@@ -3,6 +3,7 @@ const chalk = require('chalk');
 const which = require('which');
 const spawn = require('cross-spawn');
 const ErrorMessage = require('./error-message');
+const {backwardsCompatiblePath} = require('./npx');
 
 /**
  * @import {Options} from "./types/options"
@@ -19,7 +20,7 @@ const ErrorMessage = require('./error-message');
 async function getElmBinary(options) {
   if (options.compiler === undefined) {
     try {
-      return await which('elm');
+      return await which('elm', {path: backwardsCompatiblePath()});
     } catch {
       throw new ErrorMessage.CustomError(
         // prettier-ignore

lib/npx.js

@@ -0,0 +1,76 @@
+/**
+ * A fast `npx` alternative.
+ */
+
+const path = require('node:path');
+const getPathKey = require('path-key');
+
+/**
+ * The key for `process.env` containing the path, generally `PATH`.
+ *
+ * @type {string}
+ */
+const pathKey = getPathKey();
+
+/**
+ * Prepends `node_modules/.bin` up to the root directory to the PATH.
+ *
+ * @remarks
+ * When `--elm-format-path` was _not_ provided, we used to execute
+ * `elm-format` like this:
+ *
+ * 1. Try `npx elm-format`
+ * 2. Try `elm-format`
+ *
+ * Just starting `npx` takes 200 ms though. Luckily, `npx` isn’t even
+ * necessary, because the common ways of running `elm-review` are:
+ *
+ * 1. Install everything globally and run just `elm-review`.
+ * 2. Install everything locally and run `npx elm-review`.
+ * 3. Use the `--elm-format-path`.
+ *
+ * However, `npx` adds all potential `node_modules/.bin` up to current directory to the
+ * beginning of PATH, for example:
+ *
+ * ```sh
+ * $ npx node -p 'process.env.PATH.split(require("path").delimiter)'
+ * [
+ *   '/Users/you/stuff/node_modules/.bin',
+ *   '/Users/you/node_modules/.bin',
+ *   '/Users/node_modules/.bin',
+ *   '/node_modules/.bin',
+ *   '/usr/bin',
+ *   'etc'
+ * ]
+ * ```
+ *
+ * So if a user runs `npx elm-review`, when we later try to spawn just
+ * `elm-format`, it’ll be found since when spawning we inherit the same PATH.
+ *
+ * The `npx elm-format` approach has been removed to avoid those unnecessary 200 ms,
+ * but to stay backwards compatible we prepend the same paths to the beginning
+ * of PATH just like `npx` would (see above). This is needed when:
+ *
+ * - Executing `elm-review` _without_ `npx`/`npm exec`, npm scripts, or `--elm-format-path`.
+ * - And expecting a _local_ `elm-format` to be used.
+ *   That’s an odd use case, but was supported due to the `npx` approach.
+ *
+ * This can be removed in a major version.
+ */
+function backwardsCompatiblePath() {
+  return [
+    ...process
+      .cwd()
+      .split(path.sep)
+      .map((_, index, parts) =>
+        [...parts.slice(0, index + 1), 'node_modules', '.bin'].join(path.sep)
+      )
+      .reverse(),
+    process.env[pathKey]
+  ].join(path.delimiter);
+}
+
+module.exports = {
+  backwardsCompatiblePath,
+  pathKey
+};

test/jest-helpers/cli.js

@@ -52,14 +52,7 @@ async function internalExec(args, options = {}) {
 
   try {
     const result = await exec(
-      [
-        colorFlag,
-        cli,
-        reportMode(options),
-        colors(options),
-        ...(args.includes('--compiler') ? [] : [elmPath()]),
-        args
-      ].join(' '),
+      [colorFlag, cli, reportMode(options), colors(options), args].join(' '),
       {
         ...options,
         cwd: cwdFromOptions(options)
@@ -71,19 +64,6 @@ async function internalExec(args, options = {}) {
   }
 }
 
-function elmPath() {
-  const elmPath = path.resolve(
-    __dirname,
-    '..',
-    '..',
-    'node_modules',
-    '.bin',
-    'elm'
-  );
-
-  return `--compiler=${elmPath}`;
-}
-
 /**
  * @param {Options} options
  */

tsconfig.no-implicit-any.json

@@ -17,18 +17,19 @@
     "lib/sync-get.js",
     "lib/sync-get-worker.js",
     "lib/error-message.js",
+    "lib/path-helpers.js",
     "lib/flags.js",
     "lib/fs-wrapper.js",
     "lib/hash.js",
     "lib/help.js",
     "lib/load-compiled-app.js",
     "lib/min-version.js",
     "lib/new-rule.js",
+    "lib/npx.js",
     "lib/options.js",
     "lib/os-helpers.js",
     "lib/parse-elm.js",
     "lib/parse-elm-worker.js",
-    "lib/path-helpers.js",
     "lib/project-json-files.js",
     "lib/promisify-port.js",
     "lib/report.js",