Fix tests

tests/unit/test_req.py

@@ -770,11 +770,16 @@ def test_install_req_drop_extras(self, inp: str, out: str) -> None:
         without_extras = install_req_drop_extras(req)
         assert not without_extras.extras
         assert str(without_extras.req) == out
-        # should always be a copy
-        assert req is not without_extras
-        assert req.req is not without_extras.req
+
+        # if there are no extras they should be the same object,
+        # otherwise they may be a copy due to cache
+        if req.extras:
+            assert req is not without_extras
+            assert req.req is not without_extras.req
+
         # comes_from should point to original
         assert without_extras.comes_from is req
+
         # all else should be the same
         assert without_extras.link == req.link
         assert without_extras.markers == req.markers
@@ -790,9 +795,9 @@ def test_install_req_drop_extras(self, inp: str, out: str) -> None:
     @pytest.mark.parametrize(
         "inp, extras, out",
         [
-            ("pkg", {}, "pkg"),
-            ("pkg==1.0", {}, "pkg==1.0"),
-            ("pkg[ext]", {}, "pkg[ext]"),
+            ("pkg", set(), "pkg"),
+            ("pkg==1.0", set(), "pkg==1.0"),
+            ("pkg[ext]", set(), "pkg[ext]"),
             ("pkg", {"ext"}, "pkg[ext]"),
             ("pkg==1.0", {"ext"}, "pkg[ext]==1.0"),
             ("pkg==1.0", {"ext1", "ext2"}, "pkg[ext1,ext2]==1.0"),
@@ -816,9 +821,14 @@ def test_install_req_extend_extras(
         assert str(extended.req) == out
         assert extended.req is not None
         assert set(extended.extras) == set(extended.req.extras)
-        # should always be a copy
-        assert req is not extended
-        assert req.req is not extended.req
+
+        # if extras is not a subset of req.extras then the extended
+        # requirement object should not be the same, otherwise they
+        # might be a copy due to cache
+        if not extras.issubset(req.extras):
+            assert req is not extended
+            assert req.req is not extended.req
+
         # all else should be the same
         assert extended.link == req.link
         assert extended.markers == req.markers