你可以写一个实用函数来truncates所有的数据库表：

async function clearDatabase(app: INestApplication): Promise<void> {
    const entityManager = app.get<EntityManager>(EntityManager);
    const tableNames = entityManager.connection.entityMetadatas
        .map((entity) => entity.tableName)
        .join(', ');

    await entityManager.query(
        `truncate ${tableNames} restart identity cascade;`,
    );
}

然后在你的测试文件中，你只需要使用afterEach调用这个函数：

describe('Context', () => {
    let app: INestApplication;

    beforeAll(async () => {
        const appModule = await Test.createTestingModule({
            imports: [DatabaseModule],
        }).compile();

        app = appModule.createNestApplication();
        await app.init();
    });

    afterEach(async () => {
        await clearDatabase(app);
        await app.close();
    });
});