XLSX.jl locks file on Windows / Julia 0.7

[zundertj]

While attempting to make this package run on Julia 0.7-beta2, I ran into this (I cannot reproduce this on Julia 0.6.2!)

I'm on a Windows 10 machine, and this error keeps popping up while running the tests on the very last line where rm("output_tables.xlsx") is called:

ERROR: LoadError: unlink: resource busy or locked (EBUSY)
Stacktrace:
 [1] uv_error at .\libuv.jl:80 [inlined]
 [2] unlink(::String) at .\file.jl:741
 [3] #rm#9(::Bool, ::Bool, ::Function, ::String) at .\file.jl:253
 [4] rm(::String) at .\file.jl:245
 [5] top-level scope at none:0
 [6] include at .\boot.jl:317 [inlined]
 [7] include_relative(::Module, ::String) at .\loading.jl:1034
 [8] include(::Module, ::String) at .\sysimg.jl:29
 [9] include(::String) at .\client.jl:393
 [10] top-level scope at none:0
in expression starting at C:\Users\Gebruiker\.julia\dev\XLSX\test\runtests.jl:1035
ERROR: Package XLSX errored during testing

Apparantly, this is a common problem on Windows with respect to file IO, see for instance https://discourse.julialang.org/t/windows-specific-uv-error/3127/8.

I suspect that it might (partially) be a base Julia bug, but for some reason it only fails at the last rm("output_tables.xlsx"), and not on previous calls. Do you have any idea what is so special about this last time, are there operations in the final set of tests that make it lock the file?

[zundertj]

Nevermind, I'm now also running into this on earlier calls to rm() in the test suite... Still, good for you to know that on Windows+Julia 0.7 tests are likely to fail because of this.

[felipenoris]

I don't know how to fix this.

[zundertj]

The question is: can you, or someone else, reproduce this (in Julia 0.7/1.0)?

[felipenoris]

Yes... travis build reproduced this problem (in Julia 0.6). I tried to fix it by ensuring deallocation of variables that could be locking the file, and also by calling gc() manually. But it didn't work. Maybe I'm leaving some stream opened after calling close method, but I can't find the problem.

[felipenoris]

https://ci.appveyor.com/project/felipenoris/xlsx-jl/build/1.0.3/job/esc8f8vk5vvoc5g8