Add support for dt.timedelta to travel class

CHANGELOG.rst

@@ -2,6 +2,10 @@
 Changelog
 =========
 
+* Add support for ``datetime.timedelta`` to ``time_machine.travel()``.
+
+  Thanks to Nate Dudenhoeffer in `PR #298 <https://github.com/adamchainz/time-machine/pull/298>`__.
+
 * Add ``shift()`` method to the ``time_machine`` pytest fixture.
 
   Thanks to Stefaan Lippens in `PR #312 <https://github.com/adamchainz/time-machine/pull/312>`__.

README.rst

@@ -77,6 +77,9 @@ It may be:
   If it has ``tzinfo`` set to a |zoneinfo-instance|_, the current timezone will also be mocked.
 * A ``datetime.date``.
   This will be converted to a UTC datetime with the time 00:00:00.
+* A ``datetime.timedelta``.
+  This will be interpreted relative to the current time.
+  If already within a ``travel()`` block, the ``shift()`` method is easier to use (documented below).
 * A ``float`` or ``int`` specifying a `Unix timestamp <https://en.m.wikipedia.org/wiki/Unix_time>`__
 * A string, which will be parsed with `dateutil.parse <https://dateutil.readthedocs.io/en/stable/parser.html>`__ and converted to a timestamp.
   Again, if the result is naive, it will be assumed to have the UTC time zone.

src/time_machine/__init__.py

@@ -84,6 +84,7 @@
     int,
     float,
     dt.datetime,
+    dt.timedelta,
     dt.date,
     str,
 ]
@@ -124,6 +125,8 @@ def extract_timestamp_tzname(
         if dest.tzinfo is None:
             dest = dest.replace(tzinfo=dt.timezone.utc)
         timestamp = dest.timestamp()
+    elif isinstance(dest, dt.timedelta):
+        timestamp = time() + dest.total_seconds()
     elif isinstance(dest, dt.date):
         timestamp = dt.datetime.combine(
             dest, dt.time(0, 0), tzinfo=dt.timezone.utc

tests/test_time_machine.py

@@ -444,6 +444,24 @@ def test_destination_date():
     assert time.time() == EPOCH
 
 
+def test_destination_timedelta():
+    now = time.time()
+    with time_machine.travel(dt.timedelta(seconds=3600)):
+        assert now + 3600 <= time.time() <= now + 3601
+
+
+def test_destination_timedelta_negative():
+    now = time.time()
+    with time_machine.travel(dt.timedelta(seconds=-3600)):
+        assert now - 3600 <= time.time() <= now - 3599
+
+
+def test_destination_timedelta_nested():
+    with time_machine.travel(EPOCH):
+        with time_machine.travel(dt.timedelta(seconds=10)):
+            assert time.time() == EPOCH + 10.0
+
+
 @time_machine.travel("1970-01-01 00:01 +0000")
 def test_destination_string():
     assert time.time() == EPOCH + 60.0