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oriches
#1 Posted : Monday, October 15, 2012 4:59:44 PM(UTC)
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I have a scenario where I'm self hosting a RESTful web service inside the test class to test a REST client I've written. Each of these test classes creates a self hosted WebAPI service on a unique port and therefore I want to run all of the unit tests for a particular test class in a serial manner - i.e. the test class is only created once per running execution of nCrunch.

I would like to be able to run the tests in parallel at the test class granularity, will this be supported in the future?

Ideally I would like to select the test classes I want to run serially and have every other unit test run in parallel.


I have a blog post describing what I'm attempting to do:

http://awkwardcoder.blog...ervice-inside-test.html

If you need more info let me know...


Great product by the way and I'll be buying a licence :)


ta

Ollie
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Remco
#2 Posted : Monday, October 15, 2012 8:25:13 PM(UTC)
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Hi Ollie,

Thanks for posting, and for offering your support to NCrunch by buying a license!

I may have a magic trick to help you with this problem. It's the NCrunch.Framework.SerialAttribute. Any tests marked with this attribute will be mutually exclusive with everything else, which may give the result that I think you're after.

Still though, I generally try to encourage people to write tests in such a way as to support concurrency. Is the self-host service initialisation time the main constraint you're dealing with? Or is it that the self-host service impacts static data in such a way that it can only be initialised once?

On the side, I have to say that this is a really brilliant way to perform integration testing on REST clients. I didn't know it was so easily possible, otherwise I think I would have put it to use in many a project myself!


Cheers,

Remco
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oriches
#3 Posted : Monday, October 15, 2012 8:39:22 PM(UTC)
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Total agree with the idea of writing tests to support concurrency - nCrunch has really highlighted...

The issue I have is the fact only one service can use a HTTP port at anyone time, so for my test I have several test for the HTTP GET verb so I run all the tests on the same port by using the TestFixtureSetUp attributed method so the service is setup once for all the tests.

Now I could try selecting an incremental port number from static class so each test could then be run concurrently but this seems a little overkill, but i think I'll give it ago...

'I didn't know it was so easily possible' - good innit :)


O.
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Remco
#4 Posted : Monday, October 15, 2012 8:50:48 PM(UTC)
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Something you might find is that if you set the port numbers from a static member, you may still end up with the same problem when NCrunch tries to run the tests in parallel across multiple processes.

As there isn't really an easy way to share state between execution processes (and this would be a bad idea anyway), you may want to look into generating a random port number within a large range. Assuming the range is big enough, it's extremely unlikely that both executing tests will find a way to come up with the same number at the same time.

If you want a more reliable way to come up with a port number, you could also derive it from the currently executing process ID. As mentioned, NCrunch will only perform parallel execution across multiple processes, which means that the process ID of the test runner will always be different for each test being run in parallel. The ports 0-1000 are generally used by other protocols, and it isn't commonplace for a process to be numbered above 64535, so you might just want to do:

System.Diagnostics.Process.GetCurrentProcess().Id + 1000

See if this does the trick :)


Cheers,

Remco
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oriches
#5 Posted : Monday, October 15, 2012 9:30:06 PM(UTC)
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I'll give it ago and let you know...
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oriches
#6 Posted : Wednesday, October 17, 2012 4:38:41 PM(UTC)
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Found the issue and it wasn't nCrunch, it was how I was shutting down the WebAPI self hosting instance - I've blogged about it here http://awkwardcoder.blog...us-testing-and-self.html
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Remco
#7 Posted : Wednesday, October 17, 2012 6:04:52 PM(UTC)
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Awesome, thanks for letting me know!
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