下面提供一组使用 pytest 与 pytest-mock 的单元测试示例，覆盖正向、边界和反向场景，并对依赖进行模拟与交互断言。请将 your_module 替换为实际模块名。
文件名示例：tests/test_user_service.py
import pytest
from datetime import datetime
from unittest.mock import call
替换为实际的模块路径
from your_module import (
UserService,
User,
EmailValidator,
UserRepository,
Clock,
Mailer,
)
@pytest.fixture
def fixed_now():
return datetime(2024, 1, 2, 3, 4, 5)
@pytest.fixture
def make_service(mocker, fixed_now):
def _make(email_valid=True, exists=False, save_id="u_123"):
repo = mocker.create_autospec(UserRepository, instance=True)
email_validator = mocker.create_autospec(EmailValidator, instance=True)
clock = mocker.create_autospec(Clock, instance=True)
mailer = mocker.create_autospec(Mailer, instance=True)
email_validator.is_valid.return_value = email_valid
repo.exists_username.return_value = exists
repo.save.return_value = save_id
clock.now.return_value = fixed_now
service = UserService(repo, email_validator, clock, mailer)
return service, repo, email_validator, clock, mailer
return _make
def test_register_user_success_order_and_fields(mocker, fixed_now, make_service, capsys):
service, repo, email_validator, clock, mailer = make_service()
# 断言调用顺序：exists_username -> save -> send_welcome
def save_side_effect(user):
assert repo.exists_username.call_count == 1
return "u_123"
repo.save.side_effect = save_side_effect
def send_welcome_side_effect(email, username):
# send_welcome 调用前应已 save 一次
assert repo.save.call_count == 1
saved_user = repo.save.call_args[0][0]
assert saved_user.username == username
assert saved_user.email == email
mailer.send_welcome.side_effect = send_welcome_side_effect
result = service.register_user(
username="john_doe",
email="john@example.com",
password="Abc12345",
referral_code="ABC123"
)
assert result == {
"id": "u_123",
"username": "john_doe",
"created_at": fixed_now.isoformat() + "Z",
"referral_code": "ABC123",
}
email_validator.is_valid.assert_called_once_with("john@example.com")
repo.exists_username.assert_called_once_with("john_doe")
repo.save.assert_called_once()
# 校验保存的 User 对象
saved_user = repo.save.call_args[0][0]
assert isinstance(saved_user, User)
assert saved_user.id is None
assert saved_user.username == "john_doe"
assert saved_user.email == "john@example.com"
assert saved_user.created_at == fixed_now
assert saved_user.referral_code == "ABC123"
mailer.send_welcome.assert_called_once_with("john@example.com", "john_doe")
captured = capsys.readouterr()
assert captured.out == ""
assert captured.err == ""
@pytest.mark.parametrize("username", ["abc", "a" * 20])
@pytest.mark.parametrize("referral", ["ABCDEF", "A" * 12])
def test_register_user_boundary_username_and_referral(mocker, fixed_now, make_service, username, referral, capsys):
service, repo, email_validator, clock, mailer = make_service()
result = service.register_user(
username=username,
email="u@example.com",
password="Abc12345", # 正好8，包含字母和数字
referral_code=referral
)
assert result["id"] == "u_123"
assert result["username"] == username
assert result["created_at"] == fixed_now.isoformat() + "Z"
assert result["referral_code"] == referral
email_validator.is_valid.assert_called_once_with("u@example.com")
repo.exists_username.assert_called_once_with(username)
repo.save.assert_called_once()
mailer.send_welcome.assert_called_once_with("u@example.com", username)
captured = capsys.readouterr()
assert captured.out == ""
assert captured.err == ""
def test_register_user_success_no_referral(mocker, fixed_now, make_service, capsys):
service, repo, email_validator, clock, mailer = make_service()
result = service.register_user(
username="user_123",
email="ok@example.com",
password="Abc12345",
referral_code=None
)
assert result == {
"id": "u_123",
"username": "user_123",
"created_at": fixed_now.isoformat() + "Z",
"referral_code": None,
}
email_validator.is_valid.assert_called_once_with("ok@example.com")
repo.exists_username.assert_called_once_with("user_123")
repo.save.assert_called_once()
mailer.send_welcome.assert_called_once_with("ok@example.com", "user_123")
captured = capsys.readouterr()
assert captured.out == ""
assert captured.err == ""
def test_register_user_invalid_email_short_circuit(mocker, make_service, capsys):
service, repo, email_validator, clock, mailer = make_service(email_valid=False)
with pytest.raises(ValueError, match="invalid_email"):
service.register_user(username="john_doe", email="bad@", password="Abc12345", referral_code="ABC123")
email_validator.is_valid.assert_called_once_with("bad@")
repo.exists_username.assert_not_called()
repo.save.assert_not_called()
mailer.send_welcome.assert_not_called()
captured = capsys.readouterr()
assert captured.out == ""
assert captured.err == ""
def test_register_user_weak_password_too_short_short_circuit(mocker, make_service, capsys):
service, repo, email_validator, clock, mailer = make_service(email_valid=True)
with pytest.raises(ValueError, match="weak_password: length < 8"):
service.register_user(username="john_doe", email="john@example.com", password="Abc123", referral_code="ABC123")
email_validator.is_valid.assert_called_once_with("john@example.com")
repo.exists_username.assert_not_called()
repo.save.assert_not_called()
mailer.send_welcome.assert_not_called()
captured = capsys.readouterr()
assert captured.out == ""
assert captured.err == ""
@pytest.mark.parametrize("pwd", ["abcdefgh", "12345678"])
def test_register_user_weak_password_missing_letters_or_digits_short_circuit(mocker, make_service, pwd, capsys):
service, repo, email_validator, clock, mailer = make_service(email_valid=True)
with pytest.raises(ValueError, match="weak_password: must contain letters and digits"):
service.register_user(username="john_doe", email="john@example.com", password=pwd, referral_code="ABC123")
email_validator.is_valid.assert_called_once_with("john@example.com")
repo.exists_username.assert_not_called()
repo.save.assert_not_called()
mailer.send_welcome.assert_not_called()
captured = capsys.readouterr()
assert captured.out == ""
assert captured.err == ""
@pytest.mark.parametrize("bad_referral", ["ABCDE", "abc!", "A" * 13])
def test_register_user_invalid_referral_short_circuit(mocker, make_service, bad_referral, capsys):
service, repo, email_validator, clock, mailer = make_service(email_valid=True)
with pytest.raises(ValueError, match="invalid_referral_code"):
service.register_user(username="john_doe", email="john@example.com", password="Abc12345", referral_code=bad_referral)
email_validator.is_valid.assert_called_once_with("john@example.com")
repo.exists_username.assert_not_called()
repo.save.assert_not_called()
mailer.send_welcome.assert_not_called()
captured = capsys.readouterr()
assert captured.out == ""
assert captured.err == ""
def test_register_user_username_taken(mocker, make_service, capsys):
service, repo, email_validator, clock, mailer = make_service(email_valid=True, exists=True)
with pytest.raises(ValueError, match="username_taken"):
service.register_user(username="john_doe", email="john@example.com", password="Abc12345", referral_code="ABC123")
email_validator.is_valid.assert_called_once_with("john@example.com")
repo.exists_username.assert_called_once_with("john_doe")
repo.save.assert_not_called()
mailer.send_welcome.assert_not_called()
captured = capsys.readouterr()
assert captured.out == ""
assert captured.err == ""
说明：
- 使用 pytest 和 pytest-mock 的 autospec 来严格模拟依赖，避免接口漂移。
- 正向用例断言：保存对象内容、返回值、时间戳格式（包含 Z）、依赖调用次数与参数，并用 side_effect 断言调用顺序：exists_username -> save -> send_welcome。
- 边界用例使用 parametrize 覆盖用户名长度最小/最大、推荐码最小/最大、密码恰好8位且包含字母数字。
- 反向用例分别覆盖邮箱校验失败、密码过短、密码缺少字母或数字、非法推荐码、重复用户名，断言抛出特定错误消息且依赖不被调用，实现短路行为验证。
- 使用 capsys 校验无额外输出，便于在 CI 并行执行和覆盖率统计。
