ci: Delete some duplicate code in cli tests (no-changelog) (#9049)

packages/cli/test/shared/mocking.ts

@@ -1,6 +1,7 @@
 import { Container } from 'typedi';
 import { mock } from 'jest-mock-extended';
 import type { DeepPartial } from 'ts-essentials';
+import { DataSource, EntityManager, type EntityMetadata } from '@n8n/typeorm';
 import type { Class } from 'n8n-core';
 
 export const mockInstance = <T>(
@@ -11,3 +12,13 @@ export const mockInstance = <T>(
 	Container.set(serviceClass, instance);
 	return instance;
 };
+
+export const mockEntityManager = (entityClass: Class) => {
+	const entityManager = mockInstance(EntityManager);
+	const dataSource = mockInstance(DataSource, {
+		manager: entityManager,
+		getMetadata: () => mock<EntityMetadata>({ target: entityClass }),
+	});
+	Object.assign(entityManager, { connection: dataSource });
+	return entityManager;
+};