jest、prismaを使ったテストで Jest did not exit one second after the test run has completed. が出たときの解決法

test.ts

import { PrismaClient } from "@prisma/client";

const prisma = new PrismaClient();

describe("sample", () => {
  test("sample", async () => {
    const user = await prisma.user.findFirst();
    expect(user).toBeTruthy();
  });
});

これを実行すると
Jest did not exit one second after the test run has completed.
が出た。

解決法

await prisma.$disconnect();　を追加する

test.ts

import { PrismaClient } from "@prisma/client";

const prisma = new PrismaClient();

describe("sample", () => {

// 追加
afterAll(async () => {
    await prisma.$disconnect();
  });

  test("sample", async () => {
    const user = await prisma.user.findFirst();
    expect(user).toBeTruthy();
  });
});