[Buildroot] [PATCH] support/testing: TestNoTimezone: fix the test case for Glibc

[Buildroot] [PATCH] support/testing: TestNoTimezone: fix the test case for Glibc

[Romain Naour]

We have changed to a Glibc based toolchain recently [1] but the
behavior of TZ handling is not the same between libc implementation
when no Zone Database is installed.

musl and uClibc-ng return "UTC" when the data file of the requested
time zone is missing or when TZ is not set.

 # TZ=America/Los_Angeles date +%Z
 UTC

 # TZ= date +%Z
 UTC

Glibc return all or part of TZ content or "Universal" if TZ is empty.

 # TZ=America/Los_Angeles date +%Z
 America

 # TZ= date +%Z
 Universal

As demonstrated by TestAllTimezone, Glibc return "PDT" when the
America/Los_Angeles time zone data file is installed:

 # TZ=America/Los_Angeles date +%Z
 PDT

Since the Glibc behavior seems weird (not a bug [2]) when TZ is
set but the time zone data file is missing, update our test
to check against a string defined in the Glibc code [3].

[1] f89f52168fcb667a3e8e43f6f44d5b1ca3961a8c
[2] https://sourceware.org/bugzilla/show_bug.cgi?id=30710
[3] https://sourceware.org/git/?p=glibc.git;a=blob;f=time/tzset.c;h=78c18f8147415c92dc6eb735be672fa7e0b8f76e;hb=47b76f6d1d3a5ad13e585dbcc616aaea62b8bb20#l380

Ref:
https://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html

Fixe:
https://gitlab.com/buildroot.org/buildroot/-/jobs/4768561117

Signed-off-by: Romain Naour <romain.naour@gmail.com>
---
 support/testing/tests/core/test_timezone.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/support/testing/tests/core/test_timezone.py b/support/testing/tests/core/test_timezone.py
index 0e5009494d..bf4a47fcde 100644
--- a/support/testing/tests/core/test_timezone.py
+++ b/support/testing/tests/core/test_timezone.py
@@ -22,8 +22,11 @@ class TestNoTimezone(infra.basetest.BRTest):
         boot_armv5_cpio(self.emulator, self.builddir)
         tz, _ = self.emulator.run("TZ=UTC date +%Z")
         self.assertEqual(tz[0].strip(), "UTC")
-        tz, _ = self.emulator.run("TZ=America/Los_Angeles date +%Z")
-        self.assertEqual(tz[0].strip(), "UTC")
+        # This test is Glibc specific since there is no Time Zone Database installed
+        # and other C libraries use their own rule for returning time zone name or
+        # abbreviation when TZ is empty or set with a not installed time zone data file.
+        tz, _ = self.emulator.run("TZ= date +%Z")
+        self.assertEqual(tz[0].strip(), "Universal")
 
 
 class TestAllTimezone(infra.basetest.BRTest):
-- 
2.41.0

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Re: [Buildroot] [PATCH] support/testing: TestNoTimezone: fix the test case for Glibc

[Thomas Petazzoni via buildroot]

On Tue,  1 Aug 2023 15:21:13 +0200
Romain Naour <romain.naour@gmail.com> wrote:

> We have changed to a Glibc based toolchain recently [1] but the
> behavior of TZ handling is not the same between libc implementation
> when no Zone Database is installed.
> 
> musl and uClibc-ng return "UTC" when the data file of the requested
> time zone is missing or when TZ is not set.
> 
>  # TZ=America/Los_Angeles date +%Z
>  UTC
> 
>  # TZ= date +%Z
>  UTC
> 
> Glibc return all or part of TZ content or "Universal" if TZ is empty.
> 
>  # TZ=America/Los_Angeles date +%Z
>  America
> 
>  # TZ= date +%Z
>  Universal
> 
> As demonstrated by TestAllTimezone, Glibc return "PDT" when the
> America/Los_Angeles time zone data file is installed:
> 
>  # TZ=America/Los_Angeles date +%Z
>  PDT
> 
> Since the Glibc behavior seems weird (not a bug [2]) when TZ is
> set but the time zone data file is missing, update our test
> to check against a string defined in the Glibc code [3].
> 
> [1] f89f52168fcb667a3e8e43f6f44d5b1ca3961a8c
> [2] https://sourceware.org/bugzilla/show_bug.cgi?id=30710
> [3] https://sourceware.org/git/?p=glibc.git;a=blob;f=time/tzset.c;h=78c18f8147415c92dc6eb735be672fa7e0b8f76e;hb=47b76f6d1d3a5ad13e585dbcc616aaea62b8bb20#l380
> 
> Ref:
> https://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html
> 
> Fixe:
> https://gitlab.com/buildroot.org/buildroot/-/jobs/4768561117
> 
> Signed-off-by: Romain Naour <romain.naour@gmail.com>
> ---
>  support/testing/tests/core/test_timezone.py | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)

Applied to master, thanks.

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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