feat: add loadESLint api

lib/api.js

@@ -9,11 +9,24 @@
 // Requirements
 //-----------------------------------------------------------------------------
 
-const { ESLint } = require("./eslint/eslint");
+const { ESLint, shouldUseFlatConfig } = require("./eslint/eslint");
+const { LegacyESLint } = require("./eslint/legacy-eslint");
 const { Linter } = require("./linter");
 const { RuleTester } = require("./rule-tester");
 const { SourceCode } = require("./source-code");
 
+/**
+ * Loads the appropriate ESLint class based on the provided options.
+ * @param {Object} options The options for loading ESLint.
+ * @param {boolean} options.useFlatConfig Whether to use flat configuration.
+ * @returns {Object} - The ESLint class to use.
+ */
+async function loadESLint(options = {}) {
+    const useFlatConfig = options.useFlatConfig ?? (await shouldUseFlatConfig());
+
+    return useFlatConfig ? ESLint : LegacyESLint;
+}
+
 //-----------------------------------------------------------------------------
 // Exports
 //-----------------------------------------------------------------------------
@@ -22,5 +35,6 @@ module.exports = {
     Linter,
     ESLint,
     RuleTester,
-    SourceCode
+    SourceCode,
+    loadESLint
 };

lib/unsupported-api.js

@@ -22,7 +22,7 @@ const { LegacyESLint } = require("./eslint/legacy-eslint");
 module.exports = {
     builtinRules: require("./rules"),
     FlatESLint,
-    shouldUseFlatConfig,
     FileEnumerator,
-    LegacyESLint
+    LegacyESLint,
+    shouldUseFlatConfig
 };

tests/lib/api.js

@@ -41,4 +41,8 @@ describe("api", () => {
     it("should have SourceCode exposed", () => {
         assert.isFunction(api.SourceCode);
     });
+
+    it("should have loadESLint exposed", () => {
+        assert.isFunction(api.loadESLint);
+    });
 });