Re: [libvirt] [PATCH 2/9] tests: qemuxml2xml: Always use different output file

On 01/28/2016 03:30 PM, Cole Robinson wrote: > Most qemuxml2xml tests expect that the input XML is unchanged after > parsing. This is unlike 99% of new qemu configs in the wild, which after > initial parsing end up with stable PCI device addresses. The xml2xml bit > doesn't currently hit that code path though, so most XML testing indeed > does not change. > > Future patches will add that PCI address bits, which means most test cases > will have different output. So let's do away with the hardcoded same vs > different test split, and always track a separate output file. Tests can > still have same input and output, it just necessitates 2 separate XML files. > --- > .../qemuxml2xmlout-aarch64-aavmf-virtio-mmio.xml | 49 +++++ If there's going to be a ton of new files added anyway, this is a good chance to shorten the names of all the files (and avoid needing to do it to so many more files later). I've always thought it was pointless to have a file called qemuxml2xmloutdata/qemuxml2xmlout-blah.xml why not just: qemuxml2xmloutdata/blah.xml ?? I recall there being problems with running make rpm (or maybe make distcheck?) because some filename in one of these directories was beyond the tarfile name length limit or something like that.

I went back and read Martin's opinion about adding all these files, and your response. It's true that we aren't *explicitly* testing the PCI address assignment directly in the xml2xml tests now. It does end up being tested in the xml2argvtests though (except for devices that are at fixed PCI addresses which don't show up on the qemu commandline, e.g. builtin IDE controller in 440fx or builtin SATA on q35). Of course it would be a lot easier to see what's going on if the XML files could be compared, rather than trying to compare qemu commandlines and backtracking to find the offending device in the XML :-) Do you know what percentage of these files end up being different between source and result after all your changes are done? If it's all/most of them, then I think it would be a lot of extra effort for no gain to setup symbolic links now only to have them broken a few commits later.

(A bit of thinking out loud follows...) Anyway, even once we add the PCI address assignment into the qemuxml2xmltest, we still may have a considerable number of tests that have the PCI address in the source xml already anyway. Also, I think too many of the tests have been created with the following formula: 1) copy testfiles for some random existing test 2) add on a line or two that tests the new feature This has the upside of testing combinations of items that might not otherwise be tested, but there's nothing methodical about it, and we're ending up testing the same bits hundreds of times in exactly the same way. *AND* (the most important) if something is purposefully changed in one of those bits that is unnecessarily copied to a couple hundred tests (e.g. the output now has a PCI address in the element), then that change must be accompanied by changes to hundreds of test output files. It might be useful to eliminate a bunch of this duplication of tests. But of course that would be *very* tedious, and the potential for accidentally removing a useful and unique combination would be high (especially if we fell to the temptation of letting a newcomer do such a trimming as a "starter" project).

(anyway...) It would be nice if we could move all the tests that are there merely for checking genericxml2xml over to that test in advance of this change in order to reduce the churn, but I understand your reluctance to do that - it will involve a lot more subjective decisions about what was the purpose of various test cases (and for some of those the only clue you may have is the name of the data file), so it seems like a large annoying bookkeeping job when what you really need is to make ARM work correctly :-)

Since we already have hundreds of test files, and this seems to be moving in the right direction (although taking a nasty side-step), I'm inclined to ACK this patch. We should maybe put it to some kind of informal vote, though, just to make sure everyone's concerns are properly addressed (and maybe someone will come up with a bright idea)