Jest Error: Matcher error: received value must be a promise - jestjs

Question

I am writing unit tests for my NestJS application. However, I am getting into this error which I don't get how I can resolve. I am resolving the Promise as well.
My update function in service.ts looks like this:
async update(uname: string, updateUserDto: UpdateUserDTO): Promise<Users> {
const updateUser = await prisma.users.findUnique({
where: {
username: uname,
},
});
if (!updateUser || updateUser.username !== uname) {
throw new NotFoundException('User not found');
}
await prisma.tasks.updateMany({
where: {
userId: uname,
},
data: {
userId: uname,
},
});
return prisma.users.update({
where: {
username: uname,
},
data: {
...updateUserDto,
},
});
}
And my testing file looks like this.
controller.spec.ts:
describe('Update a user', () => {
it('should update the username of a user', async () => {
const updatedUser: UpdateUserDTO = {
name: 'Hulk',
};
await expect(
controller.update('wolverine', updatedUser)
).resolves.toEqual({
username: 'wolverine',
...updatedUser,
});
});
});
});
Update mock in controller.spec.ts is like this:
update: jest
.fn()
.mockImplementation((username: string, user: UpdateUserDTO) =>
Promise.resolve({ username, ...user })
),
And my controller where I am using update is, controller.spec.ts
#Patch(':uname')
update(#Param('uname') uname: string, #Body() updateUserDto: UpdateUserDTO) {
return this.usersService.update(uname, updateUserDto);
}