Refs #25774, #26348 -- Allowed Trunc functions to operate with time fields.

Thanks Josh for the amazing testing setup and Tim for the review.

11 files changed, 245 insertions, 35 deletions

diff --git a/django/db/backends/base/operations.py b/django/db/backends/base/operations.py
index 794cc15c6b..63081ba113 100644
--- a/django/db/backends/base/operations.py
+++ b/django/db/backends/base/operations.py
@@ -113,6 +113,14 @@ class BaseDatabaseOperations(object):
         """
         raise NotImplementedError('subclasses of BaseDatabaseOperations may require a datetime_trunk_sql() method')
 
+    def time_trunc_sql(self, lookup_type, field_name):
+        """
+        Given a lookup_type of 'hour', 'minute' or 'second', returns the SQL
+        that truncates the given time field field_name to a time object with
+        only the given specificity.
+        """
+        raise NotImplementedError('subclasses of BaseDatabaseOperations may require a time_trunc_sql() method')
+
     def time_extract_sql(self, lookup_type, field_name):
         """
         Given a lookup_type of 'hour', 'minute' or 'second', returns the SQL
diff --git a/django/db/backends/mysql/operations.py b/django/db/backends/mysql/operations.py
index b9b8cd9089..5ced46f970 100644
--- a/django/db/backends/mysql/operations.py
+++ b/django/db/backends/mysql/operations.py
@@ -70,6 +70,18 @@ class DatabaseOperations(BaseDatabaseOperations):
             sql = "CAST(DATE_FORMAT(%s, '%s') AS DATETIME)" % (field_name, format_str)
         return sql, params
 
+    def time_trunc_sql(self, lookup_type, field_name):
+        fields = {
+            'hour': '%%H:00:00',
+            'minute': '%%H:%%i:00',
+            'second': '%%H:%%i:%%s',
+        }  # Use double percents to escape.
+        if lookup_type in fields:
+            format_str = fields[lookup_type]
+            return "CAST(DATE_FORMAT(%s, '%s') AS TIME)" % (field_name, format_str)
+        else:
+            return "TIME(%s)" % (field_name)
+
     def date_interval_sql(self, timedelta):
         return "INTERVAL '%d 0:0:%d:%d' DAY_MICROSECOND" % (
             timedelta.days, timedelta.seconds, timedelta.microseconds), []
diff --git a/django/db/backends/oracle/operations.py b/django/db/backends/oracle/operations.py
index 4a5f52479b..0a6a239956 100644
--- a/django/db/backends/oracle/operations.py
+++ b/django/db/backends/oracle/operations.py
@@ -148,6 +148,18 @@ WHEN (new.%(col_name)s IS NULL)
             sql = "CAST(%s AS DATE)" % field_name  # Cast to DATE removes sub-second precision.
         return sql, []
 
+    def time_trunc_sql(self, lookup_type, field_name):
+        # The implementation is similar to `datetime_trunc_sql` as both
+        # `DateTimeField` and `TimeField` are stored as TIMESTAMP where
+        # the date part of the later is ignored.
+        if lookup_type == 'hour':
+            sql = "TRUNC(%s, 'HH24')" % field_name
+        elif lookup_type == 'minute':
+            sql = "TRUNC(%s, 'MI')" % field_name
+        elif lookup_type == 'second':
+            sql = "CAST(%s AS DATE)" % field_name  # Cast to DATE removes sub-second precision.
+        return sql
+
     def get_db_converters(self, expression):
         converters = super(DatabaseOperations, self).get_db_converters(expression)
         internal_type = expression.output_field.get_internal_type()
diff --git a/django/db/backends/postgresql/operations.py b/django/db/backends/postgresql/operations.py
index 9b64615001..2130571a05 100644
--- a/django/db/backends/postgresql/operations.py
+++ b/django/db/backends/postgresql/operations.py
@@ -56,6 +56,9 @@ class DatabaseOperations(BaseDatabaseOperations):
         sql = "DATE_TRUNC('%s', %s)" % (lookup_type, field_name)
         return sql, params
 
+    def time_trunc_sql(self, lookup_type, field_name):
+        return "DATE_TRUNC('%s', %s)::time" % (lookup_type, field_name)
+
     def deferrable_sql(self):
         return " DEFERRABLE INITIALLY DEFERRED"
 
diff --git a/django/db/backends/sqlite3/base.py b/django/db/backends/sqlite3/base.py
index 4f52cc3637..70d511f108 100644
--- a/django/db/backends/sqlite3/base.py
+++ b/django/db/backends/sqlite3/base.py
@@ -213,6 +213,7 @@ class DatabaseWrapper(BaseDatabaseWrapper):
         conn.create_function("django_datetime_extract", 3, _sqlite_datetime_extract)
         conn.create_function("django_datetime_trunc", 3, _sqlite_datetime_trunc)
         conn.create_function("django_time_extract", 2, _sqlite_time_extract)
+        conn.create_function("django_time_trunc", 2, _sqlite_time_trunc)
         conn.create_function("django_time_diff", 2, _sqlite_time_diff)
         conn.create_function("django_timestamp_diff", 2, _sqlite_timestamp_diff)
         conn.create_function("regexp", 2, _sqlite_regexp)
@@ -370,6 +371,19 @@ def _sqlite_date_trunc(lookup_type, dt):
         return "%i-%02i-%02i" % (dt.year, dt.month, dt.day)
 
 
+def _sqlite_time_trunc(lookup_type, dt):
+    try:
+        dt = backend_utils.typecast_time(dt)
+    except (ValueError, TypeError):
+        return None
+    if lookup_type == 'hour':
+        return "%02i:00:00" % dt.hour
+    elif lookup_type == 'minute':
+        return "%02i:%02i:00" % (dt.hour, dt.minute)
+    elif lookup_type == 'second':
+        return "%02i:%02i:%02i" % (dt.hour, dt.minute, dt.second)
+
+
 def _sqlite_datetime_parse(dt, tzname):
     if dt is None:
         return None
diff --git a/django/db/backends/sqlite3/operations.py b/django/db/backends/sqlite3/operations.py
index 1daa38fe50..4b7fc091db 100644
--- a/django/db/backends/sqlite3/operations.py
+++ b/django/db/backends/sqlite3/operations.py
@@ -70,6 +70,13 @@ class DatabaseOperations(BaseDatabaseOperations):
         # cause a collision with a field name).
         return "django_date_trunc('%s', %s)" % (lookup_type.lower(), field_name)
 
+    def time_trunc_sql(self, lookup_type, field_name):
+        # sqlite doesn't support DATE_TRUNC, so we fake it with a user-defined
+        # function django_date_trunc that's registered in connect(). Note that
+        # single quotes are used because this is a string (and could otherwise
+        # cause a collision with a field name).
+        return "django_time_trunc('%s', %s)" % (lookup_type.lower(), field_name)
+
     def _require_pytz(self):
         if settings.USE_TZ and pytz is None:
             raise ImproperlyConfigured("This query requires pytz, but it isn't installed.")
diff --git a/django/db/models/functions/datetime.py b/django/db/models/functions/datetime.py
index 2980460709..85a398a50b 100644
--- a/django/db/models/functions/datetime.py
+++ b/django/db/models/functions/datetime.py
@@ -151,26 +151,38 @@ class TruncBase(TimezoneMixin, Transform):
         elif isinstance(self.output_field, DateField):
             sql = connection.ops.date_trunc_sql(self.kind, inner_sql)
             params = []
+        elif isinstance(self.output_field, TimeField):
+            sql = connection.ops.time_trunc_sql(self.kind, inner_sql)
+            params = []
         else:
-            raise ValueError('Trunc only valid on DateField or DateTimeField.')
+            raise ValueError('Trunc only valid on DateField, TimeField, or DateTimeField.')
         return sql, inner_params + params
 
     def resolve_expression(self, query=None, allow_joins=True, reuse=None, summarize=False, for_save=False):
         copy = super(TruncBase, self).resolve_expression(query, allow_joins, reuse, summarize, for_save)
         field = copy.lhs.output_field
         # DateTimeField is a subclass of DateField so this works for both.
-        assert isinstance(field, DateField), (
-            "%r isn't a DateField or DateTimeField." % field.name
+        assert isinstance(field, (DateField, TimeField)), (
+            "%r isn't a DateField, TimeField, or DateTimeField." % field.name
         )
         # If self.output_field was None, then accessing the field will trigger
         # the resolver to assign it to self.lhs.output_field.
-        if not isinstance(copy.output_field, (DateField, DateTimeField)):
-            raise ValueError('output_field must be either DateField or DateTimeField')
-        # Passing dates to functions expecting datetimes is most likely a
-        # mistake.
+        if not isinstance(copy.output_field, (DateField, DateTimeField, TimeField)):
+            raise ValueError('output_field must be either DateField, TimeField, or DateTimeField')
+        # Passing dates or times to functions expecting datetimes is most
+        # likely a mistake.
+        output_field = copy.output_field
+        explicit_output_field = field.__class__ != copy.output_field.__class__
         if type(field) == DateField and (
-                isinstance(copy.output_field, DateTimeField) or copy.kind in ('hour', 'minute', 'second')):
-            raise ValueError("Cannot truncate DateField '%s' to DateTimeField. " % field.name)
+                isinstance(output_field, DateTimeField) or copy.kind in ('hour', 'minute', 'second', 'time')):
+            raise ValueError("Cannot truncate DateField '%s' to %s. " % (
+                field.name, output_field.__class__.__name__ if explicit_output_field else 'DateTimeField'
+            ))
+        elif isinstance(field, TimeField) and (
+                isinstance(output_field, DateTimeField) or copy.kind in ('year', 'month', 'day', 'date')):
+            raise ValueError("Cannot truncate TimeField '%s' to %s. " % (
+                field.name, output_field.__class__.__name__ if explicit_output_field else 'DateTimeField'
+            ))
         return copy
 
     def convert_value(self, value, expression, connection, context):
@@ -184,8 +196,10 @@ class TruncBase(TimezoneMixin, Transform):
                 value = value.replace(tzinfo=None)
                 value = timezone.make_aware(value, self.tzinfo)
         elif isinstance(value, datetime):
-            # self.output_field is definitely a DateField here.
-            value = value.date()
+            if isinstance(self.output_field, DateField):
+                value = value.date()
+            elif isinstance(self.output_field, TimeField):
+                value = value.time()
         return value
 
 
@@ -209,6 +223,7 @@ class TruncDay(TruncBase):
 
 
 class TruncDate(TruncBase):
+    kind = 'date'
     lookup_name = 'date'
 
     @cached_property
@@ -227,25 +242,13 @@ class TruncDate(TruncBase):
 class TruncHour(TruncBase):
     kind = 'hour'
 
-    @cached_property
-    def output_field(self):
-        return DateTimeField()
-
 
 class TruncMinute(TruncBase):
     kind = 'minute'
 
-    @cached_property
-    def output_field(self):
-        return DateTimeField()
-
 
 class TruncSecond(TruncBase):
     kind = 'second'
 
-    @cached_property
-    def output_field(self):
-        return DateTimeField()
-
 
 DateTimeField.register_lookup(TruncDate)
diff --git a/docs/ref/models/database-functions.txt b/docs/ref/models/database-functions.txt
index d6c48f966c..20ceadde91 100644
--- a/docs/ref/models/database-functions.txt
+++ b/docs/ref/models/database-functions.txt
@@ -288,8 +288,10 @@ We'll be using the following model in examples of each function::
     class Experiment(models.Model):
         start_datetime = models.DateTimeField()
         start_date = models.DateField(null=True, blank=True)
+        start_time = models.TimeField(null=True, blank=True)
         end_datetime = models.DateTimeField(null=True, blank=True)
         end_date = models.DateField(null=True, blank=True)
+        end_time = models.TimeField(null=True, blank=True)
 
 ``Extract``
 -----------
@@ -500,13 +502,14 @@ but not the exact second, then ``Trunc`` (and its subclasses) can be useful to
 filter or aggregate your data. For example, you can use ``Trunc`` to calculate
 the number of sales per day.
 
-``Trunc`` takes a single ``expression``, representing a ``DateField`` or
-``DateTimeField``, a ``kind`` representing a date part, and an ``output_field``
-that's either ``DateTimeField()`` or ``DateField()``. It returns a datetime or
-date, depending on ``output_field``, with fields up to ``kind`` set to their
-minimum value. If ``output_field`` is omitted, it will default to the
-``output_field`` of ``expression``. A ``tzinfo`` subclass, usually provided by
-``pytz``, can be passed to truncate a value in a specific timezone.
+``Trunc`` takes a single ``expression``, representing a ``DateField``,
+``TimeField``, or ``DateTimeField``, a ``kind`` representing a date or time
+part, and an ``output_field`` that's either ``DateTimeField()``,
+``TimeField()``, or ``DateField()``. It returns a datetime, date, or time
+depending on ``output_field``, with fields up to ``kind`` set to their minimum
+value. If ``output_field`` is omitted, it will default to the ``output_field``
+of ``expression``. A ``tzinfo`` subclass, usually provided by ``pytz``, can be
+passed to truncate a value in a specific timezone.
 
 Given the datetime ``2015-06-15 14:30:50.000321+00:00``, the built-in ``kind``\s
 return:
@@ -616,6 +619,61 @@ that deal with date-parts can be used with ``DateField``::
     2016-01-01 00:00:00+11:00 1
     2014-06-01 00:00:00+10:00 1
 
+``TimeField`` truncation
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. versionadded:: 1.11
+
+.. class:: TruncHour(expression, output_field=None, tzinfo=None, **extra)
+
+    .. attribute:: kind = 'hour'
+
+.. class:: TruncMinute(expression, output_field=None, tzinfo=None, **extra)
+
+    .. attribute:: kind = 'minute'
+
+.. class:: TruncSecond(expression, output_field=None, tzinfo=None, **extra)
+
+    .. attribute:: kind = 'second'
+
+These are logically equivalent to ``Trunc('time_field', kind)``. They truncate
+all parts of the time up to ``kind`` which allows grouping or filtering times
+with less precision. ``expression`` can have an ``output_field`` of either
+``TimeField`` or ``DateTimeField``.
+
+Since ``TimeField``\s don't have a date component, only ``Trunc`` subclasses
+that deal with time-parts can be used with ``TimeField``::
+
+    >>> from datetime import datetime
+    >>> from django.db.models import Count, TimeField
+    >>> from django.db.models.functions import TruncHour
+    >>> from django.utils import timezone
+    >>> start1 = datetime(2014, 6, 15, 14, 30, 50, 321, tzinfo=timezone.utc)
+    >>> start2 = datetime(2014, 6, 15, 14, 40, 2, 123, tzinfo=timezone.utc)
+    >>> start3 = datetime(2015, 12, 31, 17, 5, 27, 999, tzinfo=timezone.utc)
+    >>> Experiment.objects.create(start_datetime=start1, start_time=start1.time())
+    >>> Experiment.objects.create(start_datetime=start2, start_time=start2.time())
+    >>> Experiment.objects.create(start_datetime=start3, start_time=start3.time())
+    >>> experiments_per_hour = Experiment.objects.annotate(
+    ...    hour=TruncHour('start_datetime', output_field=TimeField()),
+    ... ).values('hour').annotate(experiments=Count('id'))
+    >>> for exp in experiments_per_hour:
+    ...     print(exp['hour'], exp['experiments'])
+    ...
+    14:00:00 2
+    17:00:00 1
+
+    >>> import pytz
+    >>> melb = pytz.timezone('Australia/Melbourne')
+    >>> experiments_per_hour = Experiment.objects.annotate(
+    ...    hour=TruncHour('start_datetime', tzinfo=melb),
+    ... ).values('hour').annotate(experiments=Count('id'))
+    >>> for exp in experiments_per_hour:
+    ...     print(exp['hour'], exp['experiments'])
+    ...
+    2014-06-16 00:00:00+10:00 2
+    2016-01-01 04:00:00+11:00 1
+
 ``DateTimeField`` truncation
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/docs/releases/1.11.txt b/docs/releases/1.11.txt
index 2359eec910..392ded70b8 100644
--- a/docs/releases/1.11.txt
+++ b/docs/releases/1.11.txt
@@ -198,6 +198,9 @@ Models
 * :class:`~django.db.models.ImageField` now has a default
   :data:`~django.core.validators.validate_image_file_extension` validator.
 
+* Added support for time truncation to
+  :class:`~django.db.models.functions.datetime.Trunc` functions.
+
 Requests and Responses
 ~~~~~~~~~~~~~~~~~~~~~~
 
@@ -263,7 +266,12 @@ Backwards incompatible changes in 1.11
 Database backend API
 --------------------
 
-* ...
+* The ``DatabaseOperations.time_trunc_sql()`` method is added to support
+  ``TimeField`` truncation. It accepts a ``lookup_type`` and ``field_name``
+  arguments and returns the appropriate SQL to truncate the given time field
+  ``field_name`` to a time object with only the given specificity. The
+  ``lookup_type`` argument can be either ``'hour'``, ``'minute'``, or
+  ``'second'``.
 
 Dropped support for PostgreSQL 9.2 and PostGIS 2.0
 --------------------------------------------------
diff --git a/tests/db_functions/test_datetime.py b/tests/db_functions/test_datetime.py
index 011db8bb88..e727ea5b7d 100644
--- a/tests/db_functions/test_datetime.py
+++ b/tests/db_functions/test_datetime.py
@@ -5,7 +5,7 @@ from unittest import skipIf
 
 from django.conf import settings
 from django.db import connection
-from django.db.models import DateField, DateTimeField, IntegerField
+from django.db.models import DateField, DateTimeField, IntegerField, TimeField
 from django.db.models.functions import (
     Extract, ExtractDay, ExtractHour, ExtractMinute, ExtractMonth,
     ExtractSecond, ExtractWeekDay, ExtractYear, Trunc, TruncDate, TruncDay,
@@ -353,18 +353,25 @@ class DateFunctionTests(TestCase):
         self.create_model(start_datetime, end_datetime)
         self.create_model(end_datetime, start_datetime)
 
-        with self.assertRaisesMessage(ValueError, 'output_field must be either DateField or DateTimeField'):
+        msg = 'output_field must be either DateField, TimeField, or DateTimeField'
+        with self.assertRaisesMessage(ValueError, msg):
             list(DTModel.objects.annotate(truncated=Trunc('start_datetime', 'year', output_field=IntegerField())))
 
-        with self.assertRaisesMessage(AssertionError, "'name' isn't a DateField or DateTimeField."):
+        with self.assertRaisesMessage(AssertionError, "'name' isn't a DateField, TimeField, or DateTimeField."):
             list(DTModel.objects.annotate(truncated=Trunc('name', 'year', output_field=DateTimeField())))
 
         with self.assertRaisesMessage(ValueError, "Cannot truncate DateField 'start_date' to DateTimeField"):
             list(DTModel.objects.annotate(truncated=Trunc('start_date', 'second')))
 
+        with self.assertRaisesMessage(ValueError, "Cannot truncate TimeField 'start_time' to DateTimeField"):
+            list(DTModel.objects.annotate(truncated=Trunc('start_time', 'month')))
+
         with self.assertRaisesMessage(ValueError, "Cannot truncate DateField 'start_date' to DateTimeField"):
             list(DTModel.objects.annotate(truncated=Trunc('start_date', 'month', output_field=DateTimeField())))
 
+        with self.assertRaisesMessage(ValueError, "Cannot truncate TimeField 'start_time' to DateTimeField"):
+            list(DTModel.objects.annotate(truncated=Trunc('start_time', 'second', output_field=DateTimeField())))
+
         def test_datetime_kind(kind):
             self.assertQuerysetEqual(
                 DTModel.objects.annotate(
@@ -389,9 +396,24 @@ class DateFunctionTests(TestCase):
                 lambda m: (m.start_datetime, m.truncated)
             )
 
+        def test_time_kind(kind):
+            self.assertQuerysetEqual(
+                DTModel.objects.annotate(
+                    truncated=Trunc('start_time', kind, output_field=TimeField())
+                ).order_by('start_datetime'),
+                [
+                    (start_datetime, truncate_to(start_datetime.time(), kind)),
+                    (end_datetime, truncate_to(end_datetime.time(), kind))
+                ],
+                lambda m: (m.start_datetime, m.truncated)
+            )
+
         test_date_kind('year')
         test_date_kind('month')
         test_date_kind('day')
+        test_time_kind('hour')
+        test_time_kind('minute')
+        test_time_kind('second')
         test_datetime_kind('year')
         test_datetime_kind('month')
         test_datetime_kind('day')
@@ -428,6 +450,12 @@ class DateFunctionTests(TestCase):
         )
         self.assertEqual(DTModel.objects.filter(start_datetime=TruncYear('start_datetime')).count(), 1)
 
+        with self.assertRaisesMessage(ValueError, "Cannot truncate TimeField 'start_time' to DateTimeField"):
+            list(DTModel.objects.annotate(truncated=TruncYear('start_time')))
+
+        with self.assertRaisesMessage(ValueError, "Cannot truncate TimeField 'start_time' to DateTimeField"):
+            list(DTModel.objects.annotate(truncated=TruncYear('start_time', output_field=TimeField())))
+
     def test_trunc_month_func(self):
         start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
         end_datetime = truncate_to(microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123)), 'month')
@@ -454,6 +482,12 @@ class DateFunctionTests(TestCase):
         )
         self.assertEqual(DTModel.objects.filter(start_datetime=TruncMonth('start_datetime')).count(), 1)
 
+        with self.assertRaisesMessage(ValueError, "Cannot truncate TimeField 'start_time' to DateTimeField"):
+            list(DTModel.objects.annotate(truncated=TruncMonth('start_time')))
+
+        with self.assertRaisesMessage(ValueError, "Cannot truncate TimeField 'start_time' to DateTimeField"):
+            list(DTModel.objects.annotate(truncated=TruncMonth('start_time', output_field=TimeField())))
+
     def test_trunc_date_func(self):
         start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
         end_datetime = microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123))
@@ -472,6 +506,12 @@ class DateFunctionTests(TestCase):
         )
         self.assertEqual(DTModel.objects.filter(start_datetime__date=TruncDate('start_datetime')).count(), 2)
 
+        with self.assertRaisesMessage(ValueError, "Cannot truncate TimeField 'start_time' to DateField"):
+            list(DTModel.objects.annotate(truncated=TruncDate('start_time')))
+
+        with self.assertRaisesMessage(ValueError, "Cannot truncate TimeField 'start_time' to DateField"):
+            list(DTModel.objects.annotate(truncated=TruncDate('start_time', output_field=TimeField())))
+
     def test_trunc_day_func(self):
         start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
         end_datetime = truncate_to(microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123)), 'day')
@@ -490,6 +530,12 @@ class DateFunctionTests(TestCase):
         )
         self.assertEqual(DTModel.objects.filter(start_datetime=TruncDay('start_datetime')).count(), 1)
 
+        with self.assertRaisesMessage(ValueError, "Cannot truncate TimeField 'start_time' to DateTimeField"):
+            list(DTModel.objects.annotate(truncated=TruncDay('start_time')))
+
+        with self.assertRaisesMessage(ValueError, "Cannot truncate TimeField 'start_time' to DateTimeField"):
+            list(DTModel.objects.annotate(truncated=TruncDay('start_time', output_field=TimeField())))
+
     def test_trunc_hour_func(self):
         start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
         end_datetime = truncate_to(microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123)), 'hour')
@@ -506,6 +552,14 @@ class DateFunctionTests(TestCase):
             ],
             lambda m: (m.start_datetime, m.extracted)
         )
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=TruncHour('start_time')).order_by('start_datetime'),
+            [
+                (start_datetime, truncate_to(start_datetime.time(), 'hour')),
+                (end_datetime, truncate_to(end_datetime.time(), 'hour')),
+            ],
+            lambda m: (m.start_datetime, m.extracted)
+        )
         self.assertEqual(DTModel.objects.filter(start_datetime=TruncHour('start_datetime')).count(), 1)
 
         with self.assertRaisesMessage(ValueError, "Cannot truncate DateField 'start_date' to DateTimeField"):
@@ -530,6 +584,14 @@ class DateFunctionTests(TestCase):
             ],
             lambda m: (m.start_datetime, m.extracted)
         )
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=TruncMinute('start_time')).order_by('start_datetime'),
+            [
+                (start_datetime, truncate_to(start_datetime.time(), 'minute')),
+                (end_datetime, truncate_to(end_datetime.time(), 'minute')),
+            ],
+            lambda m: (m.start_datetime, m.extracted)
+        )
         self.assertEqual(DTModel.objects.filter(start_datetime=TruncMinute('start_datetime')).count(), 1)
 
         with self.assertRaisesMessage(ValueError, "Cannot truncate DateField 'start_date' to DateTimeField"):
@@ -554,6 +616,14 @@ class DateFunctionTests(TestCase):
             ],
             lambda m: (m.start_datetime, m.extracted)
         )
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=TruncSecond('start_time')).order_by('start_datetime'),
+            [
+                (start_datetime, truncate_to(start_datetime.time(), 'second')),
+                (end_datetime, truncate_to(end_datetime.time(), 'second'))
+            ],
+            lambda m: (m.start_datetime, m.extracted)
+        )
 
         result = 1 if connection.features.supports_microsecond_precision else 2
         self.assertEqual(DTModel.objects.filter(start_datetime=TruncSecond('start_datetime')).count(), result)
@@ -680,9 +750,24 @@ class DateFunctionWithTimeZoneTests(DateFunctionTests):
                 lambda m: (m.start_datetime, m.truncated)
             )
 
+        def test_time_kind(kind, tzinfo=melb):
+            self.assertQuerysetEqual(
+                DTModel.objects.annotate(
+                    truncated=Trunc('start_time', kind, output_field=TimeField(), tzinfo=melb)
+                ).order_by('start_datetime'),
+                [
+                    (start_datetime, truncate_to(start_datetime.time(), kind)),
+                    (end_datetime, truncate_to(end_datetime.time(), kind))
+                ],
+                lambda m: (m.start_datetime, m.truncated)
+            )
+
         test_date_kind('year')
         test_date_kind('month')
         test_date_kind('day')
+        test_time_kind('hour')
+        test_time_kind('minute')
+        test_time_kind('second')
         test_datetime_kind('year')
         test_datetime_kind('month')
         test_datetime_kind('day')
diff --git a/tests/queries/tests.py b/tests/queries/tests.py
index 48b57376f9..e40ab1fa58 100644
--- a/tests/queries/tests.py
+++ b/tests/queries/tests.py
@@ -1312,7 +1312,7 @@ class Queries3Tests(BaseQuerysetTest):
     def test_ticket8683(self):
         # An error should be raised when QuerySet.datetimes() is passed the
         # wrong type of field.
-        with self.assertRaisesMessage(AssertionError, "'name' isn't a DateField or DateTimeField."):
+        with self.assertRaisesMessage(AssertionError, "'name' isn't a DateField, TimeField, or DateTimeField."):
             Item.objects.datetimes('name', 'month')
 
     def test_ticket22023(self):