Added get_tzinfo function in dtime API

src/senaite/core/api/dtime.py

@@ -208,7 +208,7 @@ def to_ansi(dt, show_time=True):
 
 
 def get_timezone(dt, default="Etc/GMT"):
-    """Get a valid pytz timezone of the datetime object
+    """Get a valid pytz timezone name of the datetime object
 
     :param dt: date object
     :returns: timezone as string, e.g. Etc/GMT or CET
@@ -238,6 +238,29 @@ def get_timezone(dt, default="Etc/GMT"):
     return tz
 
 
+def get_tzinfo(dt_tz, default=pytz.UTC):
+    """Returns the valid pytz tinfo from the date or timezone name
+
+    Returns the default timezone info if date does not have a valid timezone
+    set or is TZ-naive
+
+    :param dt: timezone name or date object to extract the tzinfo
+    :type dt: str/date/datetime/DateTime
+    :param: default: timezone name or pytz tzinfo object
+    :returns: pytz tzinfo object, e.g. `<UTC>, <StaticTzInfo 'Etc/GMT+2'>
+    :rtype: UTC/BaseTzInfo/StaticTzInfo/DstTzInfo
+    """
+    if is_str(default):
+        default = pytz.timezone(default)
+    try:
+        if is_str(dt_tz):
+            return pytz.timezone(dt_tz)
+        tz = get_timezone(dt_tz, default=default.zone)
+        return pytz.timezone(tz)
+    except pytz.UnknownTimeZoneError:
+        return default
+
+
 def is_valid_timezone(timezone):
     """Checks if the timezone is a valid pytz/Olson name
 
@@ -445,9 +468,9 @@ def get_relative_delta(dt1, dt2=None):
     If `dt2` is None, the current datetime is used.
 
     :param dt1: the first date/time to compare
-    :type dt1: str/date/datetime/DateTime
+    :type dt1: string/date/datetime/DateTime
     :param dt2: the second date/time to compare
-    :type dt2: str/date/datetime/DateTime
+    :type dt2: string/date/datetime/DateTime
     :returns: interval of time (e.g. `relativedelta(hours=+3)`)
     :rtype: dateutil.relativedelta
     """
@@ -459,12 +482,6 @@ def get_relative_delta(dt1, dt2=None):
     if not all([dt1, dt2]):
         return None
 
-    def get_tzinfo(dt, default=pytz.UTC):
-        try:
-            return pytz.timezone(get_timezone(dt))
-        except pytz.UnknownTimeZoneError:
-            return default
-
     naives = [is_timezone_naive(dt) for dt in [dt1, dt2]]
     if all(naives):
         # Both naive, no need to do anything special

src/senaite/core/tests/doctests/API_datetime.rst

@@ -248,6 +248,74 @@ Get the timezone from `datetime.date` objects:
     'Etc/GMT'
 
 
+Get the timezone info
+.....................
+
+Get the timezone info from TZ name:
+
+    >>> dtime.get_tzinfo("Etc/GMT")
+    <StaticTzInfo 'Etc/GMT'>
+
+    >>> dtime.get_tzinfo("Pacific/Fiji")
+    <DstTzInfo 'Pacific/Fiji' LMT+11:56:00 STD>
+
+    >>> dtime.get_tzinfo("UTC")
+    <UTC>
+
+Get the timezone info from `DateTime` objects:
+
+    >>> dtime.get_tzinfo(DateTime("2022-02-25"))
+    <StaticTzInfo 'Etc/GMT'>
+
+    >>> dtime.get_tzinfo(DateTime("2022-02-25 12:00 GMT+2"))
+    <StaticTzInfo 'Etc/GMT-2'>
+
+    >>> dtime.get_tzinfo(DateTime("2022-02-25 12:00 GMT-2"))
+    <StaticTzInfo 'Etc/GMT+2'>
+
+Get the timezone info from `datetime.datetime` objects:
+
+    >>> DATE = "2021-12-24 12:00"
+    >>> dt = datetime.strptime(DATE, DATEFORMAT)
+    >>> dtime.get_tzinfo(dt)
+    <UTC>
+
+    >>> dtime.get_tzinfo(dtime.to_zone(dt, "Europe/Berlin"))
+    <DstTzInfo 'CET' CET+1:00:00 STD>
+
+Get the timezone info from `datetime.date` objects:
+
+    >>> dtime.get_tzinfo(dt.date)
+    <UTC>
+
+Getting the timezone info from a naive date returns default timezone info:
+
+    >>> dt_naive = dt.replace(tzinfo=None)
+    >>> dtime.get_tzinfo(dt_naive)
+    <UTC>
+
+    >>> dtime.get_tzinfo(dt_naive, default="Pacific/Fiji")
+    <DstTzInfo 'Pacific/Fiji' LMT+11:56:00 STD>
+
+We can use a timezone info as the default parameter as well:
+
+    >>> dtime.get_tzinfo(dt_naive, default=dtime.pytz.UTC)
+    <UTC>
+
+Default can also be a timezone name:
+
+    >>> dtime.get_tzinfo(dt_naive, default="America/Port_of_Spain")
+    <DstTzInfo 'America/Port_of_Spain' LMT-1 day, 19:36:00 STD>
+
+And an error is rised if default is not a valid timezone, even if the date
+passed-in is valid:
+
+    >>> dtime.get_tzinfo(dt_naive, default="Atlantida")
+    Traceback (most recent call last):
+    ...
+    UnknownTimeZoneError: 'Atlantida'
+
+
 Check if timezone is valid
 ..........................