Add $datetime() function and associated tests

picard/script.py

@@ -21,6 +21,7 @@
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 
 from collections import namedtuple
+import datetime
 from functools import reduce
 from inspect import getfullargspec
 import operator
@@ -1201,3 +1202,28 @@ def func_slice(parser, multi, start_index, end_index, separator=MULTI_VALUED_JOI
         return separator.join(multi_var[start:end])
     except IndexError:
         return ''
+
+
+@script_function()
+def func_datetime(parser, format=None):
+    """Return the current date and time as a string.
+
+    Arguments:
+        parser: The ScriptParser object used to parse the script.
+        format: A string or the ScriptVariable/Function that evaluates to the
+            string used to format the output.  Default is '%Y-%m-%d %H:%M:%S'
+            if blank.  Uses strftime() format.
+
+    Returns:
+        Returns the current date and time as a string.
+    """
+    # local_tz required for Python 3.5 which does not allow setting astimezone()
+    # on a naive datetime.datetime object.  This provides timezone information to
+    # allow the use of %Z and %z in the output format.
+    local_tz = datetime.datetime.now(datetime.timezone.utc).astimezone().tzinfo
+
+    # Handle case where format evaluates to ''
+    if not format:
+        format = '%Y-%m-%d %H:%M:%S'
+
+    return datetime.datetime.now(tz=local_tz).strftime(format)

test/test_script.py

@@ -1,3 +1,4 @@
+import datetime
 from unittest.mock import MagicMock
 
 from test.picardtestcase import PicardTestCase
@@ -16,6 +17,38 @@ from picard.script import (
 )
 
 
+class _TestTimezone(datetime.tzinfo):
+    def utcoffset(self, dt):
+        # Set to GMT+2
+        return datetime.timedelta(hours=2) + self.dst(dt)
+
+    def dst(self, dt):
+        d = datetime.datetime(dt.year, 4, 1)
+        self.dston = d - datetime.timedelta(days=d.weekday() + 1)
+        d = datetime.datetime(dt.year, 11, 1)
+        self.dstoff = d - datetime.timedelta(days=d.weekday() + 1)
+        if self.dston <=  dt.replace(tzinfo=None) < self.dstoff:
+            return datetime.timedelta(hours=1)
+        else:
+            return datetime.timedelta(0)
+
+    def tzname(self,dt):
+        return "TZ Test"
+
+
+class _DateTime(datetime.datetime):
+    @classmethod
+    def now(cls, tz=None):
+        return datetime.datetime(2020, 1, 2, hour=12, minute=34, second=56, microsecond=789, tzinfo=tz)
+
+    def astimezone(self, tz=None):
+        # Ignore tz passed to the method and force use of test timezone.
+        tz = _TestTimezone()
+        utc = (self - self.utcoffset()).replace(tzinfo=tz)
+        # Convert from UTC to tz's local time.
+        return tz.fromutc(utc)
+
+
 class ScriptParserTest(PicardTestCase):
 
     def setUp(self):
@@ -943,3 +976,33 @@ class ScriptParserTest(PicardTestCase):
             self.parser.eval("$slice(abc; def,0)")
         with self.assertRaisesRegex(ScriptError, areg):
             self.parser.eval("$slice(abc; def),0,1,:,extra")
+
+    def test_cmd_datetime(self):
+        # Save origninal datetime object and substitute one returning
+        # a fixed now() value for testing.
+        original_datetime = datetime.datetime
+        datetime.datetime = _DateTime
+
+        try:
+            context = Metadata()
+            context["foo"] = "%Y%m%d%H%M%S.%f"
+            # Tests with context
+            self.assertScriptResultEquals("$datetime(%foo%)", "20200102123456.000789", context)
+            self.assertScriptResultEquals("$datetime($initials())", "2020-01-02 12:34:56", context)
+            # Tests with static input
+            self.assertScriptResultEquals("$datetime(\%Y\%m\%d\%H\%M\%S.\%f)", "20200102123456.000789", context)
+            # Tests with timezones
+            self.assertScriptResultEquals("$datetime(\%H\%M\%S \%z \%Z)", "123456 +0200 TZ Test", context)
+            # Tests with missing input
+            self.assertScriptResultEquals("$datetime()", "2020-01-02 12:34:56", context)
+            # Tests with invalid format
+            self.assertScriptResultEquals("$datetime(xxx)", "xxx", context)
+            # Tests with invalid number of arguments
+            areg = r"^Wrong number of arguments for \$datetime: Expected between 0 and 1, "
+            with self.assertRaisesRegex(ScriptError, areg):
+                self.parser.eval("$datetime(abc,def)")
+        except (AssertionError, ValueError, IndexError) as err:
+            raise err
+        finally:
+            # Restore origninal datetime object
+            datetime.datetime = original_datetime