Python Clean code tip

import json
import pathlib
from dataclass import dataclass

import pytest

@dataclass
class User:
	username: str

class InMemoryUserRepository:
	def __init__(self):
		self.users = []

	def add(self, user):
		self.users.append(user)

	def get_by_username(self, username):
		return next(user for user in self._users if user.username == username)


class JSONUserRepository:
	def __init__(self, filepath):
		self.users = json.load(pathlib.Path(file_path).open())

	def add(self, user):
		self.users.append(user)

	def get_by_username(self, username):
		return next(user for user in self._users if user.username == username)

class UserRepositoryContract:
	@pytest.fixture
	def repository(self):
		raise NotImplementedError('Not Implemented Yet.')

	@pytest.fixture
	def username(self):
		return 'Johndoe'