Make sure to use C locale during time tests that assume it

Some format and parse tests for time and date-time depended on locale
but had test data for the C locale (so fail if the test-environment
has, e.g., LANG=de_DE@utf8).  So impose the C locale (until Qt 6).

The date-time test did *some* attempts at fixing for locale, but
failed to handle am/pm; and we do have "### Qt 6" comments in
Q(Date|Time)+::fromString indicating that we intend to switch these
methods to use the C locale by default (which shall fix this once and
for all).  So rip out the incomplete localization now and test we work
properly at least when the locale used *is* C.  Add a comment to the
matching QDate test to rip out its (presently adequate) matching code
once we do get to Qt 6 and make fromString() use the C locale.

QDateTimeParser uses systemLocale(), which is initialized the first
time it gets accessed; so we need to frob the locale *early*; doing so
in the test-class constructor is about as early as we conveniently
can; and seems to work (while doing it in individual tests does not).
(There is no point rolling back at the end; the QSystemLocale global
has been set up by then, so the roll-back would merely leave the
global out of sync with setlocale() and the environment.)

Task-number: QTBUG-58728
Change-Id: Ifa6778a80276050a099387a6dab15a1096be7561
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/tests/auto/corelib/tools/qtime/tst_qtime.cpp b/tests/auto/corelib/tools/qtime/tst_qtime.cpp
index 059e1e519b..71bf39fc4e 100644
--- a/tests/auto/corelib/tools/qtime/tst_qtime.cpp
+++ b/tests/auto/corelib/tools/qtime/tst_qtime.cpp
@@ -28,10 +28,26 @@
 
 #include <QtTest/QtTest>
 #include "qdatetime.h"
+#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
+#  include <locale.h>
+#endif
 
 class tst_QTime : public QObject
 {
     Q_OBJECT
+
+#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
+public:
+    tst_QTime()
+    {
+        // Some tests depend on C locale - BF&I it with belt *and* braces:
+        qputenv("LC_ALL", "C");
+        setlocale(LC_ALL, "C");
+        // Need to instantiate as early as possible, before anything accesses
+        // the QSystemLocale singleton; once it exists, there's no changing it.
+    }
+#endif // remove for ### Qt 6
+
 private slots:
     void msecsTo_data();
     void msecsTo();