Correctly handle monkeypatching of datetime in PyPy

Author: domdfcoding

coincidence/utils.py

@@ -41,6 +41,7 @@
 
 # 3rd party
 import pytest
+from domdf_python_tools.compat import PYPY
 from domdf_python_tools.iterative import Len
 from domdf_python_tools.paths import PathPlus
 
@@ -97,42 +98,69 @@ def with_fixed_datetime(fixed_datetime: datetime.datetime):
 		Using ``from datetime import datetime`` won't work.
 	"""
 
-	class D(datetime.date):
-
-		@classmethod
-		def today(cls):
-			return datetime.date(
-					fixed_datetime.year,
-					fixed_datetime.month,
-					fixed_datetime.day,
+	if PYPY:  # pragma: no cover (!PyPy)
+
+		with pytest.MonkeyPatch.context() as monkeypatch:
+			monkeypatch.setattr(
+					datetime.date,
+					"today",
+					lambda *args: datetime.date(
+							fixed_datetime.year,
+							fixed_datetime.month,
+							fixed_datetime.day,
+							)
+					)
+			monkeypatch.setattr(
+					datetime.datetime,
+					"today",
+					lambda *args: datetime.datetime(
+							fixed_datetime.year,
+							fixed_datetime.month,
+							fixed_datetime.day,
+							)
 					)
+			monkeypatch.setattr(datetime.datetime, "now", lambda *args: fixed_datetime)
 
-	class DT(datetime.datetime):
+			yield
 
-		@classmethod
-		def today(cls):
-			return datetime.datetime(
-					fixed_datetime.year,
-					fixed_datetime.month,
-					fixed_datetime.day,
-					)
+	else:  # pragma: no cover (PyPy)
+
+		class D(datetime.date):
+
+			@classmethod
+			def today(cls):
+				return datetime.date(
+						fixed_datetime.year,
+						fixed_datetime.month,
+						fixed_datetime.day,
+						)
+
+		class DT(datetime.datetime):
+
+			@classmethod
+			def today(cls):
+				return datetime.datetime(
+						fixed_datetime.year,
+						fixed_datetime.month,
+						fixed_datetime.day,
+						)
 
-		@classmethod
-		def now(cls, tz: Optional[datetime.tzinfo] = None):
-			return datetime.datetime.fromtimestamp(fixed_datetime.timestamp())
+			@classmethod
+			def now(cls, tz: Optional[datetime.tzinfo] = None):
+				return datetime.datetime.fromtimestamp(fixed_datetime.timestamp())
 
-	D.__name__ = "date"
-	D.__qualname__ = "date"
-	DT.__qualname__ = "datetime"
-	DT.__name__ = "datetime"
-	D.__module__ = "datetime"
-	DT.__module__ = "datetime"
+		D.__name__ = "date"
+		D.__qualname__ = "date"
+		DT.__qualname__ = "datetime"
+		DT.__name__ = "datetime"
+		D.__module__ = "datetime"
+		DT.__module__ = "datetime"
 
-	with pytest.MonkeyPatch.context() as monkeypatch:
-		monkeypatch.setattr(datetime, "date", D)
-		monkeypatch.setattr(datetime, "datetime", DT)
+		with pytest.MonkeyPatch.context() as monkeypatch:
+			monkeypatch.setattr(datetime, "date", D)
+			monkeypatch.setattr(datetime, "datetime", DT)
 
-		yield
+			yield
 
 
 def generate_truthy_values(

tests/test_fixtures.py

@@ -4,6 +4,8 @@
 # 3rd party
 from domdf_python_tools.paths import PathPlus
 
+original_datetime = datetime.datetime
+
 
 def test_tmp_pathplus(tmp_pathplus: PathPlus):
 	assert isinstance(tmp_pathplus, PathPlus)
@@ -24,6 +26,9 @@ def test_fixed_datetime(fixed_datetime):
 	assert datetime.date.__qualname__ == "date"
 	assert datetime.date.__module__ == "datetime"
 
+	assert datetime.datetime.now() - datetime.datetime(2019, 10, 13, 2, 20) == datetime.timedelta(days=366)
+	assert datetime.datetime.now() - original_datetime(2019, 10, 13, 2, 20) == datetime.timedelta(days=366)
+
 
 def test_path_separator(path_separator: str):
 	assert isinstance(path_separator, str)

tests/test_utils.py

@@ -10,6 +10,8 @@
 import coincidence
 from coincidence.utils import generate_falsy_values, generate_truthy_values, with_fixed_datetime
 
+original_datetime = datetime.datetime
+
 
 def test_generate_truthy_values():
 	random.seed(1234)
@@ -117,6 +119,9 @@ def test_with_fixed_datetime(fake_datetime, expected_date: datetime.datetime):
 		assert datetime.date.__qualname__ == "date"
 		assert datetime.date.__module__ == "datetime"
 
+		datetime.datetime.now() - datetime.datetime(2019, 10, 13, 2, 20)
+		datetime.datetime.now() - original_datetime(2019, 10, 13, 2, 20)
+
 
 def test_is_docker(monkeypatch, tmp_pathplus: PathPlus):
 	cgroup = tmp_pathplus / "cgroup"