写入Visual Studio输出窗口，可靠的方式

Question

Exactly as what asked in " Writing to output window of Visual Studio? ", however solving the remaining issue --

• I assume there is no way to write to output if i start without debugging (ctrl-f5) right? – previous_developer Feb 27 '12

• Debug.WriteLine() will only work when running in Debug. That means running it with F5 and not CTRL-F5. – kirk.burleson Jul 15 '13

However, it is not the case because:

• Just ran a small app here, works fine for me. Perhaps there is a small glitch in your environment? – Bhargav Bhat Feb 27 '12

• Moreover,

I can see some Informational printed in Visual Studio output window during normal run :

[1/10/2018 11:56:25 AM Informational] ------ Run test started ------
[1/10/2018 11:56:26 AM Informational] NUnit Adapter 3.9.0.0: Test execution started
[1/10/2018 11:56:26 AM Informational] Running selected tests in  ...\Demo.dll
[1/10/2018 11:56:26 AM Informational] NUnit3TestExecutor converted 14 of 14 NUnit test cases
[1/10/2018 11:56:45 AM Informational] NUnit Adapter 3.9.0.0: Test execution complete
[1/10/2018 11:56:45 AM Informational] ========== Run test finished: 1 run (0:00:19.3066647) ==========

For to run in debug mode, The NUnit debug output will look like:

[1/10/2018 2:56:55 PM Informational] ------ Run test started ------
[1/10/2018 2:56:56 PM Informational] NUnit Adapter 3.9.0.0: Test execution started
[1/10/2018 2:56:56 PM Informational] Debugging selected tests in ...\Demo.dll
[1/10/2018 2:56:57 PM Informational] NUnit3TestExecutor converted 14 of 14 NUnit test cases
[1/10/2018 3:03:38 PM Informational] NUnit Adapter 3.9.0.0: Test execution complete
[1/10/2018 3:03:38 PM Informational] ========== Run test finished: 1 run (0:06:43.6161412) ==========

Ie, regardless normal run or in debug mode, NUnit Adapter is able to write to the Visual Studio output window, the difference is only in the text " Running selected tests " or " Debugging selected tests "

So, here is the summary of debugging output cases during normal run , not in debug mode :

• For C# Console, both Debug.WriteLine and Trace.WriteLine works fine. I've created and verified with this: https://pastebin.com/Du6ZbDV3
• However for Class/Form etc that don't have Console, neither Debug.WriteLine nor Trace.WriteLine work. Example: https://pastebin.com/b7P0bYEa . " It is pretty simple but still nothing – previous-developer Feb 27 '12 ".
• In NUnit testing, which is C# Class lib, neither Debug.WriteLine nor Trace.WriteLine works. I've run mine several times and can confirm this. I'll not be posting my test code here because it is lengthy & needs lots of libs to work, moreover, it is caused by the same glitch as https://pastebin.com/b7P0bYEa .

So all in all, How to write to Visual Studio output window from class lib or win forms?

Answer 1

To using both Debug.WriteLine and Trace.WriteLine we need add using System.Diagnostics , which only works when it's debugging (F5). Even it's a C# Console project we still cannot get Debug.WriteLine and Trace.WriteLine output when Start without Debugging (Ctrl + F5), to see the output we have to run it in Debugging (F5) .

For Class library project, it could only be built or compiled , I don't think we could Start or run it as it's not a console project unless it's been called in a console project.

UPDATE:

To debug a class library project and show its output, I add a unit test in my solution in VS. My class library code:

    namespace ClassLibrary1
{
   public class hello
    {
        public static void foo()
        {
            Console.WriteLine("Hi, this is a console writeline");
            Debug.WriteLine("Hi, this is a Debug writeline");
        }
    }
}

In unit test project I added the ClassLibrary1 to the Reference

and my unite test project code is simple:

using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using ClassLibrary1;


namespace UnitTestProject3
{
    [TestClass]
    public class UnitTest1
    {
        [TestMethod]
        public void TestMethod1()
        {
            hello.foo();

        }
    }
}

Then after running the test method i could get the output: