diff --git a/src/plugin/index.ts b/src/plugin/index.ts
index 156240be..d794f276 100644
--- a/src/plugin/index.ts
+++ b/src/plugin/index.ts
@@ -1,4 +1,5 @@
 import { Linter, Rule, SourceCode } from 'eslint';
+import { preferAdditionShorthandRule } from './prefer-addition-shorthand-rule.js';
 import { transformRule, type TransformRuleOption } from './transform-rule.js';
 import {
   type FixableMaker,
@@ -13,7 +14,9 @@ export { TransformRuleOption, type FixableMaker, type SuggestionFilter };
 
 export const eslintInteractivePlugin = {
   rules: {
-    transform: transformRule,
+    'transform': transformRule,
+    // for test
+    'prefer-addition-shorthand': preferAdditionShorthandRule,
   },
 };
 
diff --git a/src/test-util/rules/prefer-addition-shorthand.ts b/src/plugin/prefer-addition-shorthand-rule.ts
similarity index 93%
rename from src/test-util/rules/prefer-addition-shorthand.ts
rename to src/plugin/prefer-addition-shorthand-rule.ts
index a8fd068b..332b47bc 100644
--- a/src/test-util/rules/prefer-addition-shorthand.ts
+++ b/src/plugin/prefer-addition-shorthand-rule.ts
@@ -1,8 +1,12 @@
 import { Rule } from 'eslint';
 
+/**
+ * @file This is a rule for testing purposes.
+ */
+
 export type ApplyFixesRuleOption = Rule.Fix[];
 
-const rule: Rule.RuleModule = {
+export const preferAdditionShorthandRule: Rule.RuleModule = {
   meta: {
     type: 'suggestion',
     // @ts-ignore
@@ -50,6 +54,3 @@ const rule: Rule.RuleModule = {
     };
   },
 };
-
-// eslint-disable-next-line import/no-default-export
-export default rule;
diff --git a/src/test-util/transform-tester.ts b/src/test-util/transform-tester.ts
index 66d29f7e..c3e00eaa 100644
--- a/src/test-util/transform-tester.ts
+++ b/src/test-util/transform-tester.ts
@@ -1,8 +1,6 @@
 import { resolve } from 'path';
 import { Linter, ESLint } from 'eslint';
-import { TransformArg, TransformName, TransformRuleOption } from '../plugin/index.js';
-import { transformRule } from '../plugin/transform-rule.js';
-import preferAdditionShorthand from './rules/prefer-addition-shorthand.js';
+import { eslintInteractivePlugin, TransformArg, TransformName, TransformRuleOption } from '../plugin/index.js';
 
 const DEFAULT_FILENAME = 'test.js';
 
@@ -84,12 +82,7 @@ export class TransformTester<T extends TransformName> {
     return new ESLint({
       useEslintrc: false,
       plugins: {
-        'eslint-interactive': {
-          rules: {
-            'prefer-addition-shorthand': preferAdditionShorthand,
-            'transform': transformRule,
-          },
-        },
+        'eslint-interactive': eslintInteractivePlugin,
       },
       overrideConfig: {
         plugins: ['eslint-interactive', ...(this.defaultLinterConfig.plugins ?? [])],