Added ESLint v9 flat config support (#34)

* make the entrypoint compatible with eslint v9

* Add a local test

* Updated readme

* Added a flat config compatibility check

* Use eslint 9 for local development

* Fix unit tests

* Remove ESLint ignore

* Update README.md

Co-authored-by: Brett Zamir <brettz9@yahoo.com>

---------

Co-authored-by: Brett Zamir <brettz9@yahoo.com>

README.md

@@ -32,31 +32,52 @@ npm install eslint-plugin-chai-friendly --save-dev
 
 ## Usage
 
-Add `chai-friendly` to the plugins section of your `.eslintrc.*` configuration file. You can omit the `eslint-plugin-` prefix:
+Add `chai-friendly` to the plugins section of your  ESLint configuration file. Then disable original `no-unused-expressions` rule and configure chai-friendly replacement under the rules section.
 
-```json
-{
-    "plugins": [
-        "chai-friendly"
-    ]
-}
-```
+ESLint 9 flat config format:
+
+```js
+import pluginChaiFriendly from 'eslint-plugin-chai-friendly';
 
+export default {
+    plugins: {'chai-friendly': pluginChaiFriendly},
+    rules: {
+        "no-unused-expressions": "off", // disable original rule
+        "chai-friendly/no-unused-expressions": "error"
+    },
+};
+```
 
-Then disable original `no-unused-expressions` rule and configure chai-friendly replacement under the rules section.
+Legacy `.eslintrc` format:
 
 ```json
 {
+    "plugins": [
+        "chai-friendly" // you can omit the eslint-plugin- prefix
+    ],
     "rules": {
-        "no-unused-expressions": 0,
+        "no-unused-expressions": 0, // disable original rule
         "chai-friendly/no-unused-expressions": 2
     }
 }
 ```
 
 If you don't need to tweak the above rule settings, you can instead
-just add the following to your config file's `extends` and the above
-will be applied automatically:
+extend the provided recommended configuration.
+
+ESLint 9 flat config format:
+
+```js
+const pluginChaiFriendly = require("eslint-plugin-chai-friendly");
+
+module.exports = [
+    pluginChaiFriendly.configs.recommended,
+    // other configurations
+]
+```
+
+Legacy `.eslintrc` format:
+
 
 ```json
 {

eslint.config.js

@@ -0,0 +1,10 @@
+"use strict";
+
+const pluginChaiFriendly = require("./lib");
+
+module.exports = [
+    pluginChaiFriendly.configs.recommended,
+    {
+        ignores: ["node_modules", "!.eslintrc.js", "examples"],
+    }
+]

examples/test.js

@@ -0,0 +1,9 @@
+const { expect } = require('chai');
+
+// these are valid chai expect statement that should not cause any linter errors
+expect(true).to.be.true;
+foo.should.be.true;
+
+// this should cause unused expression error
+const foo = {bar: 'baz'};
+foo.bar;

lib/index.js

@@ -3,17 +3,31 @@
  * @author Ihor Diachenko
  */
 
-module.exports = {
-    configs: {
-        recommended: {
-            plugins: ['chai-friendly'],
-            rules: {
-                'chai-friendly/no-unused-expressions': 'error',
-                'no-unused-expressions': 'off'
-            }
-        }
+const pjs = require('../package.json');
+
+const plugin = {
+    meta: {
+        name: pjs.name,
+        version: pjs.version,
     },
     rules: {
         'no-unused-expressions': require('./rules/no-unused-expressions')
-    }
+    },
+    processors: {},
+    configs: {}
 };
+
+// assign configs here so we can reference `plugin`
+Object.assign(plugin.configs, {
+    recommended: {
+        plugins: {
+            'chai-friendly': plugin
+        },
+        rules: {
+            'chai-friendly/no-unused-expressions': 'error',
+            'no-unused-expressions': 'off'
+        }
+    }
+},)
+
+module.exports = plugin;