On Tue, 17 Sept 2024 at 10:33, twp...@gmail.com <twpa...@gmail.com> wrote:
> umask cannot be set in subtests for two reasons:
> 1. It is a process-wide global variable stored by the operating system.
> Changing the umask in a test changes the umask for the entire process, i.e.
> it changes the umask for all tests.
> 2. It is not possible to set and restore the umask atomically. This makes
> it inherently racy for concurrent programs.
>
I might be misunderstanding something, but neither of these seems to
actually be a problem. Tests are not run concurrently, unless explicitly
requested by calling `t.Parallel()`. The same goes for sub tests, I
believe. So, simply doing
func TestOne(t *testing.T) {
defer syscall.Umask(syscall.Umask(0))
// test goes here
}
func TestTwo(t *testing.T) {
defer syscall.Umask(syscall.Umask(0777))
// test goes here
}
Should work, AIUI, even with the issues you mention. Or is there something
else going on that I'm unaware of?
> To learn more about umask, and why it is special, please read the man page
> <https://man7.org/linux/man-pages/man2/umask.2.html>.
> On Monday, September 16, 2024 at 5:34:29 PM UTC+2 Jason Phillips wrote:
>
>> Why can't it be set within subtests? Note that subtests (like regular
>> tests) aren't run in parallel unless you explicitly call t.Parallel().
>>
>> On Friday, September 13, 2024 at 6:35:15 PM UTC-4 twp...@gmail.com wrote:
>>
>>> > Personally, I would approach this kind of thing by writing a test that
>>> sets the umask to various different values and invokes subtests with
>>> each umask value.
>>>
>>> I would love to do this but umask is a process global (as far as I
>>> understand it) and so can't be set within subtests.
>>>
>>> On Saturday, September 14, 2024 at 12:33:19 AM UTC+2 Ian Lance Taylor
>>> wrote:
>>>
>>>> On Fri, Sep 13, 2024 at 3:03 PM twp...@gmail.com <twp...@gmail.com>
>>>> wrote:
>>>> >
>>>> > tl;dr: umask is a system-wide global that affects go tests and should
>>>> be considered when validating go test's cache.
>>>> >
>>>> >
>>>> > Motivation:
>>>> >
>>>> > I'm the author of a popular open source project that writes files to
>>>> the user's home directory and cares about getting exact file permissions
>>>> correct. The file permissions depend on the the current umask setting. As
>>>> umask is a process global variable, it cannot be set for individual tests,
>>>> and so separate tests are needed for different umasks.
>>>> >
>>>> > Currently changing the umask does not invalidate go test's cache, so
>>>> I get incorrect test results if I change the umask and re-run go test.
>>>> >
>>>> >
>>>> > Suggested solution:
>>>> >
>>>> > Include umask as an op in go test's id calculation.
>>>> >
>>>> >
>>>> > Next steps:
>>>> >
>>>> > * Is this something that the Go project would consider?
>>>> > * If so, I would be happy to submit a CL.
>>>>
>>>> Personally, I would approach this kind of thing by writing a test that
>>>> sets the umask to various different values and invokes subtests with
>>>> each umask value. That way the test is independent of the external
>>>> environment.
>>>>
>>>> In general our approach has been that if your test intrinsically
>>>> depends on the external environment, then you should run it with
>>>> -test.run=1 to disable the test cache.
>>>>
>>>> Ian
>>>>
>>> --
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