test: use flat compat rule tester

Author: G-Rath

package.json

@@ -52,6 +52,7 @@
     "eslint-remote-tester": "^3.0.0",
     "eslint-remote-tester-repositories": "^1.0.1",
     "kcd-scripts": "^12.0.0",
+    "semver": "^7.6.0",
     "typescript": "^5.1.3"
   },
   "peerDependencies": {

src/__tests__/lib/rules/prefer-empty.js

@@ -8,8 +8,8 @@
 // Requirements
 //------------------------------------------------------------------------------
 
-import { RuleTester } from "eslint";
-import * as rule from "../../../rules/prefer-empty";
+import { FlatCompatRuleTester as RuleTester } from '../../rule-tester';
+import * as rule from '../../../rules/prefer-empty';
 
 //------------------------------------------------------------------------------
 // Tests

src/__tests__/lib/rules/prefer-focus.js

@@ -3,7 +3,7 @@
  * @author Ben Monro
  */
 
-import { RuleTester } from "eslint";
+import { FlatCompatRuleTester as RuleTester } from '../../rule-tester';
 import * as rule from "../../../rules/prefer-focus";
 
 const ruleTester = new RuleTester();

src/__tests__/lib/rules/prefer-in-document.js

@@ -7,7 +7,7 @@
 // Requirements
 //------------------------------------------------------------------------------
 
-import { RuleTester } from "eslint";
+import { FlatCompatRuleTester as RuleTester } from '../../rule-tester';
 import * as rule from "../../../rules/prefer-in-document";
 
 //------------------------------------------------------------------------------

src/__tests__/lib/rules/prefer-prefer-to-have-class.js

@@ -1,4 +1,4 @@
-import { RuleTester } from "eslint";
+import { FlatCompatRuleTester as RuleTester } from '../../rule-tester';
 import * as rule from "../../../rules/prefer-to-have-class";
 
 const errors = [{ messageId: "use-to-have-class" }];

src/__tests__/lib/rules/prefer-to-have-attribute.js

@@ -8,7 +8,7 @@
 // Requirements
 //------------------------------------------------------------------------------
 
-import { RuleTester } from "eslint";
+import { FlatCompatRuleTester as RuleTester } from '../../rule-tester';
 import * as rule from "../../../rules/prefer-to-have-attribute";
 
 //------------------------------------------------------------------------------

src/__tests__/lib/rules/prefer-to-have-style.js

@@ -1,4 +1,4 @@
-import { RuleTester } from "eslint";
+import { FlatCompatRuleTester as RuleTester } from '../../rule-tester';
 import * as rule from "../../../rules/prefer-to-have-style";
 
 const errors = [

src/__tests__/lib/rules/prefer-to-have-text-content.js

@@ -8,7 +8,7 @@
 // Requirements
 //------------------------------------------------------------------------------
 
-import { RuleTester } from "eslint";
+import { FlatCompatRuleTester as RuleTester } from '../../rule-tester';
 import * as rule from "../../../rules/prefer-to-have-text-content";
 
 //------------------------------------------------------------------------------

src/__tests__/lib/rules/prefer-to-have-value.js

@@ -8,7 +8,7 @@
 // Requirements
 //------------------------------------------------------------------------------
 
-import { RuleTester } from "eslint";
+import { FlatCompatRuleTester as RuleTester } from '../../rule-tester';
 import * as rule from "../../../rules/prefer-to-have-value";
 
 //------------------------------------------------------------------------------

src/__tests__/rule-tester.js

@@ -0,0 +1,58 @@
+import { RuleTester } from 'eslint';
+import semver from 'semver';
+import { version as eslintVersion } from 'eslint/package.json';
+
+export const usingFlatConfig = semver.major(eslintVersion) >= 9;
+
+export class FlatCompatRuleTester extends RuleTester {
+  constructor(testerConfig) {
+    super(FlatCompatRuleTester._flatCompat(testerConfig));
+  }
+
+  run(
+    ruleName,
+    rule,
+    tests,
+  ) {
+    super.run(ruleName, rule, {
+      valid: tests.valid.map(t => FlatCompatRuleTester._flatCompat(t)),
+      invalid: tests.invalid.map(t => FlatCompatRuleTester._flatCompat(t)),
+    });
+  }
+
+  static _flatCompat(config) {
+    if (!config || !usingFlatConfig || typeof config === 'string') {
+      return config;
+    }
+
+    const obj = {
+      languageOptions: { parserOptions: {} },
+    };
+
+    for (const [key, value] of Object.entries(config)) {
+      if (key === 'parser') {
+        obj.languageOptions.parser = require(value);
+
+        continue;
+      }
+
+      if (key === 'parserOptions') {
+        for (const [option, val] of Object.entries(value)) {
+          if (option === 'ecmaVersion' || option === 'sourceType') {
+            obj.languageOptions[option] = val
+
+            continue;
+          }
+
+          obj.languageOptions.parserOptions[option] = val;
+        }
+
+        continue;
+      }
+
+      obj[key] = value;
+    }
+
+    return obj;
+  }
+}