1 files changed, 49 insertions, 0 deletions
diff --git a/tests/interval/test_add_subtract.py b/tests/interval/test_add_subtract.py
new file mode 100644
index 0000000..88525a3
--- /dev/null
+++ b/tests/interval/test_add_subtract.py
@@ -0,0 +1,49 @@
+from __future__ import annotations
+
+import pendulum
+
+
+def test_dst_add():
+    start = pendulum.datetime(2017, 3, 7, tz="America/Toronto")
+    end = start.add(days=6)
+    period = end - start
+    new_end = start + period
+
+    assert new_end == end
+
+
+def test_dst_add_non_variable_units():
+    start = pendulum.datetime(2013, 3, 31, 1, 30, tz="Europe/Paris")
+    end = start.add(hours=1)
+    period = end - start
+    new_end = start + period
+
+    assert new_end == end
+
+
+def test_dst_subtract():
+    start = pendulum.datetime(2017, 3, 7, tz="America/Toronto")
+    end = start.add(days=6)
+    period = end - start
+    new_start = end - period
+
+    assert new_start == start
+
+
+def test_naive_subtract():
+    start = pendulum.naive(2013, 3, 31, 1, 30)
+    end = start.add(hours=1)
+    period = end - start
+    new_end = start + period
+
+    assert new_end == end
+
+
+def test_negative_difference_subtract():
+    start = pendulum.datetime(2018, 5, 28, 12, 34, 56, 123456)
+    end = pendulum.datetime(2018, 1, 1)
+
+    period = end - start
+    new_end = start + period
+
+    assert new_end == end