fix: don't error on circular eslint plugins

package.json

@@ -51,6 +51,7 @@
   },
   "dependencies": {
     "@types/eslint": "^9.6.1",
+    "flatted": "^3.3.3",
     "jest-worker": "^29.7.0",
     "micromatch": "^4.0.8",
     "normalize-path": "^3.0.0",

src/getESLint.js

@@ -6,6 +6,7 @@ const { Worker: JestWorker } = require('jest-worker');
 const { setup, lintFiles } = require('./worker');
 const { getESLintOptions } = require('./options');
 const { jsonStringifyReplacerSortKeys } = require('./utils');
+const { stringify } = require('flatted');
 
 /** @type {{[key: string]: any}} */
 const cache = {};
@@ -115,7 +116,7 @@ async function getESLint(key, { threads, ...options }) {
  * @returns {string}
  */
 function getCacheKey(key, options) {
-  return JSON.stringify({ key, options }, jsonStringifyReplacerSortKeys);
+  return stringify({ key, options }, jsonStringifyReplacerSortKeys);
 }
 
 module.exports = {

src/utils.js

@@ -104,9 +104,13 @@ const jsonStringifyReplacerSortKeys = (_, value) => {
     return sorted;
   };
 
-  return value instanceof Object && !(value instanceof Array)
-    ? Object.keys(value).sort().reduce(insert, {})
-    : value;
+  if (value instanceof Object && !(value instanceof Array)) {
+    let sorted = Object.keys(value).sort().reduce(insert, {});
+    Object.keys(value).forEach((key) => delete value[key]);
+    Object.assign(value, sorted);
+  }
+
+  return value;
 };
 
 module.exports = {

test/circular-plugin.test.js

@@ -0,0 +1,38 @@
+import pack from './utils/pack';
+import { ESLint } from 'eslint';
+
+(ESLint && parseFloat(ESLint.version) < 9 ? describe.skip : describe)(
+  'circular plugin',
+  () => {
+    it('should support plugins with circular configs', async () => {
+      const plugin = {
+        configs: {},
+        rules: {},
+        processors: {},
+      };
+
+      Object.assign(plugin.configs, {
+        recommended: {
+          plugins: {
+            self: plugin,
+          },
+          rules: {},
+        },
+      });
+
+      const loaderOptions = {
+        configType: 'flat',
+        overrideConfig: {
+          plugins: { plugin: plugin },
+        },
+        overrideConfigFile: true,
+      };
+
+      const compiler = pack('good', loaderOptions);
+
+      const stats = await compiler.runAsync();
+      expect(stats.hasWarnings()).toBe(false);
+      expect(stats.hasErrors()).toBe(false);
+    });
+  },
+);