Console Output in Unit Tests

[nbaztec]

I'm facing a issue where a particular test fails for exactly a single target, however there's no way that I can debug the actual code to fix it. I've tried with Console.WriteLine but of course the assembly isn't included within System.Net.Sockets. System.Diagnostics.Debug doesn't show up on the test log either.

Any ideas?

[stephentoub]

From within a corefx unit test you should definitely be able to use Console.WriteLine. If you mean using it within the product code in System.Net.Sockets, you could do something like:

#pragma warning disable BCL0015
[DllImport("msvcrt")]
private static extern int printf(string format, string arg);
private static void WriteLine(string s) => printf("%s\r\n", s);

on Windows, or:

#pragma warning disable BCL0015
[DllImport("libc")]
private static extern int printf(string format, string arg);
private static void WriteLine(string s) => printf("%s\n", s);

on Unix.

Or you could locally/temporarily modify https://github.com/dotnet/corefx/blob/d6646295b889daf9cf46caae1f9097b719873439/src/System.Net.Sockets/src/System.Net.Sockets.csproj#L382-L402 to include System.Console and then just use Console.WriteLine.

[stephentoub]

What's the test btw? Is it some existing test that's failing for you without any changes to System.Net.Sockets?

[nbaztec]

Thanks I'll try that, it's this test: https://mc.dot.net/#/user/nbaztec/pr~2Fjenkins~2Fdotnet~2Fcorefx~2Fmaster~2F/test~2Ffunctional~2Fcli~2F/da29f1b45f466d29d0049f0c02535bb1a668fbde/workItem/System.Net.Sockets.Tests

basically I need to see the output of DNS resolution since all the other assertions are passing.

[nbaztec]

Sadly I still couldn't get the console output after adding System.Console
https://mc.dot.net/#/user/nbaztec/pr~2Fjenkins~2Fdotnet~2Fcorefx~2Fmaster~2F/test~2Ffunctional~2Fcli~2F/01404175cb26a27435382afae2155512c1da4127/workItem/System.Net.Sockets.Tests/wilogs

[stephentoub]

Sadly I still couldn't get the console output after adding System.Console

I see output like:

2018-10-07 16:01:42,330: INFO: proc(55): run_and_log_output: Output: �[mlen: 1
2018-10-07 16:01:42,330: INFO: proc(55): run_and_log_output: Output: 127.0.0.1 InterNetwork InterNetworkV6

in those logs... what's not working?

[nbaztec]

I see, interestingly all the log outputs are missing from Windows.10.Amd64.ClientRS4.Open-x86:Release as if it uses an entirely different codebase.

[ViktorHofer]

That's .NET Framework. If your project doesn't have a netfx configuration it will just run the official assembly from the GAC. Therefore your changes and outputs are not run.

[nbaztec]

Interesting, I guessed so but wasn't sure. I don't think I will be able to patch this bug it the original GAC, as such what might be the potential solutions - we can take this discussion to dotnet/corefx#32504 since the originnal answer is sufficient, just my code is never executed.

This bug is single handedly bothering me since a week now and I'm unable to come to a solution.
Thanks for the help.