如何在不搞乱单元测试的情况下使用静态变量? [英] How do I use a static variable without messing up my unit tests?

问题描述

我有一个用户类 - 片段如下:

I have a user class - snippet as below:

public class User
    {
        private int userID;
        private static int nextID = 99;
        private String firstName;
        private String lastName;
        private String email;
        private String password;
        private String fullName;

        public User()
        {
        }

        public User(String firstName, String lastName, String email, String password)
        {
            userID = nextID + 1;
            nextID++;
            this.firstName = firstName;
            this.lastName = lastName;
            fullName = firstName + " " + lastName;
            this.email = email;
            this.password = password;
        }

我想给用户一个唯一的 UserID，每次实例化用户时都会增加.

I want to give users a unique UserID that increments each time a user is instantiated.

我尝试使用静态 int NextID 来保存下一个对象的 UserID，并在每次使用后在构造函数中递增它.

I tried doing this with a static int NextID to hold the UserID of the next object and increment it in the constructor after it is used each time.

然而，当我尝试这个时，它搞砸了我的单元测试，当我运行所有测试时，其中一些失败了，但它们在单独运行时仍然通过.

However, when I tried this, it messed up my unit tests and some of them fail when I Run All Tests but they all still pass when run individually.

有谁知道我如何在不搞乱单元测试的情况下实现这个目标?

Does anyone know how I can achieve this goal without messing up my unit tests?

推荐答案

这看起来像是一个设计问题.

This looks like a design issue.

例如，尝试分离所涉及的类的关注点.

For example, try separating the concerns of the classes involved.

public interface IUserIdManager {
    int GetNextId();
}

public interface IUserFactory {
    User Create();
    User Create(String firstName, String lastName, String email, String password);
}

让用户管理器实现依赖于创建实例时要使用的 id 管理器.

Have the user manager implementation depend on the id manager to be used when creating instances.

public class UserFactory : IUserFactory {
    private readonly IUserIdManager ids;
    public UserFactory(IUserIdManager ids) {
        this.ids = ids;
    }

    public User Create() { 
        var user = new User();
        user.UserId = ids.GetNextId();
        return user;
    }

    public User Create(String firstName, String lastName, String email, String password) { 
        var user = new User(firstName, lastName, email, password);
        user.UserId = ids.GetNextId();
        return user;
    }
}

用户类不应该关心创建自己的 id.那不是它的责任.它应该保持精益，作为一个简单的 POCO/模型来保存数据.

The user class should not be concerned with creating its own id. That is not its responsibility. It should be kept lean as a simple POCO/model to hold data.

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