如何在 c# 中为以下代码编写 nunit 测试用例？ 如何为没有 arguments 的方法编写 nunit 测试用例？

Question

How do I write unit test (using nUnit) a class that has methods with no arguments in c#? I am calling this showinfo() method in Program.cs. I want to write an nunit test case for that...but since it contains no arguments how can i test it?

 public void showInfo() //no arguments are passes here and im calling this in Program.cs
            {
                int indexNum;
                string inId = Convert.ToString(Console.ReadLine());//taking Id as input 
                Console.Write("Enter account Password :");
                string inPass = Convert.ToString(Console.ReadLine());//taking password

                if (myId.Contains(inId)&&myPass.Contains(inPass))
                {
                    Console.ForegroundColor= ConsoleColor.Green;
                    Console.WriteLine("Login Success!", Console.ForegroundColor);
                    Console.ResetColor();
                    indexNum = Array.IndexOf(myId, inId);

                    Console.WriteLine("Your details: ");
                    Console.WriteLine("Name: " + myName[indexNum]);
                    Console.WriteLine("Id: " + myId[indexNum]);
                    Console.WriteLine("Acc Type: " + myAccType[indexNum]);
                    Console.WriteLine("Date of Joining: " + myDob[indexNum]);
                    Console.WriteLine("Domain: " + myDomain[indexNum]);
                    Console.WriteLine("Manager: " + myManager[indexNum]);
                    //Console.WriteLine("Employee name: " + empl_name[indexNum]);
                    //Console.WriteLine(myId);
                }
                else
                {
                    Console.ForegroundColor = ConsoleColor.Red;
                    Console.WriteLine("Login Error!",Console.ForegroundColor);
                    Console.ResetColor();
                }
            }

Answer 1

There main issue here that's making your code difficult to test is that this one method is doing too much.

What do you want to test? In it's simplest you'll want to test the basic happy path where the user enters the correct password (more on that in a minute) and that the correct account details are output. You'll also want to test the 'unhappy path' where the user enters an incorrect password, and is shown an error message instead of the user's account details.

Further complicating this is that, in the context of your code, Console.WriteLine is a 3rd party dependency, albeit from a reputable source. In a unit test our aim is to isolate a unit of work . What this means is that you don't want to be calling the real Console.WriteLine in the method that you're unit testing. However, because Console.WriteLine is a static method it's difficult to mock , which is the approach you would normally take to isolate a unit of work. Of course you still want to ensure that the details that will be written to the screen are as expected. There are multiple approaches to this but the easiest is probably to separate the code which constructs the user output from the code which actually displays it .

Another issue here is that this method relies on state in the Program class (the myId , myPass , myName etc fields). In a unit test you need to control the values that you pass into these variables, and you can't do this if they're static members in your Program class. As a starter you could pass these into your showInfo() method, allowing you to control what you pass in to a unit test.

Summary: to make this code unit testable you need to break it down into smaller components that you can unit test individually.

Further note: your .Contains test for the user ID and password looks suspect, what happens if two people have the same password?

Edit Here's an example of how you might set about breaking this method down into smaller methods that might be individually unit tested. Note that there are still improvements that could be made to this code, but I've intentionally left this quite similar to the code in the OP so it's easier to draw comparisons between the two:

public class Class1
{
    public void showInfo(
        string[] myId,
        string[] myPass,
        string[] myName,
        string[] myAccType,
        string[] myDob,
        string[] myDomain,
        string[] myManager)
    {
        int indexNum;
        string inId = Convert.ToString(Console.ReadLine());//taking Id as input 
        Console.Write("Enter account Password :");
        string inPass = Convert.ToString(Console.ReadLine());//taking password

        if (IsPasswordValid(inId, inPass, myId, myPass))
        {
            var successOutputLines = GetSuccessOutput(
                inId,
                myId,
                myPass,
                myName,
                myAccType,
                myDob,
                myDomain,
                myManager);
            successOutputLines.ToList().ForEach(l => Console.WriteLine(l));
        }
        else
        {
            Console.ForegroundColor = ConsoleColor.Red;
            Console.WriteLine("Login Error!", Console.ForegroundColor);
            Console.ResetColor();
        }
    }

    public bool IsPasswordValid(
        string userId,
        string passwordIn,
        string[] userIds,
        string[] passwords)
    {
        var userIndex = Array.IndexOf(userIds, userId);
        if (userIndex == -1)
            throw new ArgumentException(nameof(userId));
        var expectedPassword = passwords[userIndex];
        return expectedPassword == passwordIn;
    }

    public IEnumerable<string> GetSuccessOutput(
        string userId,
        string[] myId,
        string[] myPass,
        string[] myName,
        string[] myAccType,
        string[] myDob,
        string[] myDomain,
        string[] myManager)
    {
        var userIndex = Array.IndexOf(myId, userId);
        if (userIndex == -1)
            throw new ArgumentException(nameof(userId));

        var lines = new List<string>();
        lines.Add("Login Success!");
        lines.Add("Your details: ");
        lines.Add("Your details: ");
        lines.Add("Name: " + myName[userIndex]);
        lines.Add("Id: " + myId[userIndex]);
        lines.Add("Acc Type: " + myAccType[userIndex]);
        lines.Add("Date of Joining: " + myDob[userIndex]);
        lines.Add("Domain: " + myDomain[userIndex]);
        lines.Add("Manager: " + myManager[userIndex]);

        return lines;
    }
}

You would then write unit tests for the IsPasswordValid and GetSuccessOutput methods.

Answer 2

There are many ways to test methods with no arguments, private methods, etc. You just need to set something up, so when you do test your method, it calls another method (with arguments)

In your AssemblyInfo.cs , you add an attribute

#if DEBUG #then
InternalsVisibleTo("your test project")`.
#endif

The do something like this in your class you want to test

public class A
{
#if DEBUG #then
    private MethodParameters _testParameters

    internal void SetMethodParameters(MethodParameters testParameters)
    {
        _testParameters = testParameters
    }
#endif
    public void NoArgumentMethod()
    {
#if DEBUG #then
        if (_testParameters)
        {
            PrivateArgumentMethod(_testParameters);
            return;
        }
#endif 
        // collect your arguments here and pass to private method
        var mp = new MethodParameters();
        mp.Id = _someId;
        // . . . . . 
    }

    private void PrivateArgumentMethod(MethodParameters testParameters)
    {
         // execute here
    }

    internal class MethodParameters
    {
        public int Id {get; set;}
        // more properties here
    }
}

As you see, this is pretty convoluted. There are other variations of this. Most important - you might noted that you need to compile and run unit tests in DEBUG mode for some code to be available for unit testing but not in release assemblies. Use conditional compilation for this.

But the truth is, this is bad design! You should design your classes in such way so that you can truly unit test important functionality and you can do functional tests. You can use mocks, etc. Design ahead. What I just showed - we use to test some old code, where people wrote it - UI logic, BLL logic and Data Access logic all in same file. There is no way, you should write a new code like this