feat(upgrade): adding exports of private eslint api on first rule run

.eslintrc.js

@@ -3,7 +3,7 @@
 module.exports = {
   root: true,
   parserOptions: {
-    ecmaVersion: 2019,
+    ecmaVersion: 2021,
     sourceType: 'script',
   },
   plugins: ['eslint-plugin', 'filenames', 'import', 'jest', 'node', 'prettier'],

lib/rules/decorator-position.js

@@ -1,22 +1,18 @@
 'use strict';
 
-const { CLIEngine: v7AndEarlier, ESLint: v8Plus } = require('eslint');
-
-const ESLint = v7AndEarlier || v8Plus;
-const isEslint7 = Boolean(v7AndEarlier);
-
-const cli = new ESLint();
-
-function getConfig(filePath) {
-  // < 8 support
-  if ('getConfigForFile' in cli) {
-    return cli.getConfigForFile(filePath) || {};
-  }
-
-  // This is not supported in v8 -- config checks are all async, yet rules are sync
-  return {};
+const { join } = require('path');
+const { existsSync: isExists, writeFileSync: write, readFileSync: read } = require('fs');
+
+let CLIEngine;
+try {
+  ({ CLIEngine } = require('eslint/eslint-plugin-decorator-position'));
+} catch {
+  setupEslintExports();
+  ({ CLIEngine } = require('eslint/eslint-plugin-decorator-position'));
 }
 
+const cli = CLIEngine ? new CLIEngine() : undefined;
+
 module.exports = {
   meta: {
     type: 'layout',
@@ -127,12 +123,13 @@ const INTENT = {
 };
 
 const PREFER_INLINE = 'prefer-inline';
-const ABOVE = 'above';
 
+const ABOVE = 'above';
 const PROPERTIES = 'properties';
-const METHODS = 'methods';
 
+const METHODS = 'methods';
 // specifics set by the eslint config
+
 const defaultOptions = {
   printWidth: 100,
   [PROPERTIES]: PREFER_INLINE,
@@ -142,7 +139,6 @@ const defaultOptions = {
     [ABOVE]: [],
   },
 };
-
 let prettier;
 
 function decoratorPositionRule(context) {
@@ -341,28 +337,14 @@ function lineLength(userOptions, filePath) {
     }
   }
 
-  let eslintPrettierRules = [];
-
-  try {
-    const config = getConfig(filePath);
-    const rules = config || {};
-    const prettierConfig = rules && rules['prettier/prettier'];
-    eslintPrettierRules = prettierConfig || [];
-  } catch (e) {
-    // eslint-disable-next-line no-console
-    console.warn(e);
-  }
+  const eslintPrettierRules = cli?.getConfigForFile(filePath).rules['prettier/prettier'] || [];
   const isEnabled = eslintPrettierRules[0] === 'error';
 
   if (!isEnabled) {
-    // This might be a bug, in that userOptions are ignored.
-    // But it's been the behavior, and changing it would be a
-    // breaking change
-    if (isEslint7) {
-      return { printWidth: Infinity };
-    }
+    return { printWidth: Infinity };
+  }
 
-    // Always either use userOptions or infinite printWidth
+  if (!isEnabled) {
     return { printWidth: userOptions.printWidth || Infinity };
   }
 
@@ -537,3 +519,42 @@ function arityOfDecorator(decorator) {
       return undefined;
   }
 }
+
+function findNearestEslintPackage() {
+  let dir = __dirname;
+  while (!isExists(join(dir, 'node_modules', 'eslint'))) {
+    if (dir === join(dir, '..')) {
+      throw new Error('Cannot found Eslint package');
+    }
+    dir = join(dir, '..');
+  }
+  return join(dir, 'node_modules', 'eslint');
+}
+
+function setupEslintExports() {
+  const eslintPath = findNearestEslintPackage();
+  const fileName = 'eslint-plugin-decorator-position';
+  const filePath = join(eslintPath, `${fileName}.js`);
+  if (!isExists(filePath)) {
+    const eslintPackageJson = join(eslintPath, 'package.json');
+
+    const packageJson = JSON.parse(
+      read(eslintPackageJson, {
+        encoding: 'utf-8',
+      })
+    );
+
+    write(
+      filePath,
+      `module.exports = {
+      CLIEngine: require("./lib/cli-engine").CLIEngine,
+    }`
+    );
+
+    if (packageJson.exports) {
+      packageJson.exports[`./${fileName}`] = `./${fileName}.js`;
+    }
+
+    write(eslintPackageJson, JSON.stringify(packageJson));
+  }
+}