On Wed, 2014-04-30 at 10:50 -0700, Jonathan M Davis via Digitalmars-d wrote: […] > In general, I agree. In reality, there are times when having state > across unit tests makes sense - especially when there's expensive setup > required for the tests. While it's not something that I generally > like to do, I know that we have instances of that where I work. Also, if > the unit tests have to deal with shared resources, they may very well be > theoretically independent but would run afoul of each other if run at > the same time - a prime example of this would be std.file, which has to > operate on the file system. I fully expect that if std.file's unit > tests were run in parallel, they would break. Unit tests involving > sockets would be another type of test which would be at high risk of > breaking, depending on what sockets they need.
Surely if there is expensive set up you are doing an integration or system test not a unit test. In a unit test all expensive set up should be mocked out. > Honestly, the idea of running unit tests in parallel makes me very > nervous. In general, across modules, I'd expect it to work, but there > will be occasional cases where it will break. Across the unittest > blocks in a single module, I'd be _very_ worried about breakage. There > is nothing whatsoever in the language which guarantees that running > them in parallel will work or even makes sense. All that protects us is > the convention that unit tests are usually independent of each other, > and in my experience, it's common enough that they're not independent > that I think that blindly enabling parallelization of unit tests across > a single module is definitely a bad idea. All tests should be independent, therefore there should be no problem executing all tests at the same time and/or in any order. If tests have to be executed in a specific order then they are not separate tests and should be merged into a single test — which likely means they are integration or system tests not unit tests. -- Russel. ============================================================================= Dr Russel Winder t: +44 20 7585 2200 voip: sip:russel.win...@ekiga.net 41 Buckmaster Road m: +44 7770 465 077 xmpp: rus...@winder.org.uk London SW11 1EN, UK w: www.russel.org.uk skype: russel_winder
