MAYA-112050 - Pxr tests will use build area for temporary files.

[JGamache-autodesk]

Result:

E:\Ws\UsdBuild\MayaUSD\build>ctest -V -R Package
...
163: Environment variables:
163:  TMP=E:/Ws/UsdBuild/MayaUSD/build/test/Temporary/testUsdExportPackage
163:  TEMP=E:/Ws/UsdBuild/MayaUSD/build/test/Temporary/testUsdExportPackage
...
163: Opening layer 'e:/Ws/UsdBuild/MayaUSD/build/test/Temporary/testUsdExportPackage/tmpdugxsng1/tmp-305918D1-45DE-C901-944D-D99D49A7FEB1.usdc' for writing

[JGamache-autodesk]

See https://github.com/Autodesk/maya-usd/blob/dev/cmake/test.cmake#L320 for reference.

[HamedSabri-adsk]

Thanks Jerry. Looks good.

For the sake of documentation, can you describe the scenario where you hit this?

[JGamache-autodesk]

Well, I was trying to fix the exact failure I have in the unit test that failed in this commit:

09:04:34     testArKitCompatibility (__main__.testUsdExportPackage)
09:04:34     Tests usdz package export with ARKit compatibility profile. ... Warning: This file is from an older version of Maya.  If saved, it will not be readable by previous versions.
09:04:34     File read in  0.5 seconds.
09:04:34     Viewport 2.0 floating point render target is turned off.
09:04:34     Viewport 2.0 floating point render target is turned on for color management.
09:04:34     Opening layer 'w:/build/relwithdebinfo/test/temporary/testusdexportpackage/tmpp1hsky/tmp-542FDF81-4C23-A396-84CC-E1A02D084766.usdc' for writing
09:04:34     Saving stage
09:04:34     Packaging USDZ file
09:04:34     Warning: The given asset 'w:/build/relwithdebinfo/test/temporary/testusdexportpackage/tmpp1hsky/tmp-542FDF81-4C23-A396-84CC-E1A02D084766.usdc' contains one or more composition arcs referencing external USD files. Flattening it to a single .usdc file before packaging. This will result in loss of features such as variantSets and all asset references to be absolutized.
09:04:34     Error: Failed to delete 'w:/build/relwithdebinfo/test/temporary/testusdexportpackage/tmpp1hsky/tmp-542FDF81-4C23-A396-84CC-E1A02D084766.usdc'
09:04:34     FAIL
09:04:34     testExport (__main__.testUsdExportPackage)
09:04:34     Tests standard usdz package export. ... Warning: This file is from an older version of Maya.  If saved, it will not be readable by previous versions.
09:04:34     File read in  0.078 seconds.
09:04:34     Viewport 2.0 floating point render target is turned off.
09:04:34     Viewport 2.0 floating point render target is turned on for color management.
09:04:34     Opening layer 'w:/build/relwithdebinfo/test/temporary/testusdexportpackage/tmpp1hsky/tmp-C90445CB-4D77-B559-8746-A499492BBEA0.usdc' for writing
09:04:34     Saving stage
09:04:34     Packaging USDZ file
09:04:34     FAIL

Which squarely means that this fix is not the solution. I will most probably close that PR without asking for a merge.

I suspect the USD check that a file has been really deleted in TfDeleteFile, which calls _unlink on Windows can not work if any handle is still opened on the file. On Unix OS, unlink always work because the inode held by program handles is not the same as the directory inode that unlink will always remove successfully.

Another potential fix could be done, still in USD, to make sure the temporary stage created to export the file goes out of scope before the call to TfDeleteFile.