bpo-45577: test all pickle protocols in `test_zoneinfo` (GH-29167) (GH-29295)

(cherry picked from commit 66e6b3dcd3bbab06feeff2cbaf8aade7b6223d6c)

Co-authored-by: Nikita Sobolev <mail@sobolevn.me>

2 files changed, 54 insertions, 44 deletions

diff --git a/Lib/test/test_zoneinfo/test_zoneinfo.py b/Lib/test/test_zoneinfo/test_zoneinfo.py
index d4704b7..08ebbb1 100644
--- a/Lib/test/test_zoneinfo/test_zoneinfo.py
+++ b/Lib/test/test_zoneinfo/test_zoneinfo.py
@@ -1403,44 +1403,50 @@ class ZoneInfoPickleTest(TzPathUserMixin, ZoneInfoTestBase):
         return [self.zoneinfo_data.tzpath]
 
     def test_cache_hit(self):
-        zi_in = self.klass("Europe/Dublin")
-        pkl = pickle.dumps(zi_in)
-        zi_rt = pickle.loads(pkl)
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            with self.subTest(proto=proto):
+                zi_in = self.klass("Europe/Dublin")
+                pkl = pickle.dumps(zi_in, protocol=proto)
+                zi_rt = pickle.loads(pkl)
 
-        with self.subTest(test="Is non-pickled ZoneInfo"):
-            self.assertIs(zi_in, zi_rt)
+                with self.subTest(test="Is non-pickled ZoneInfo"):
+                    self.assertIs(zi_in, zi_rt)
 
-        zi_rt2 = pickle.loads(pkl)
-        with self.subTest(test="Is unpickled ZoneInfo"):
-            self.assertIs(zi_rt, zi_rt2)
+                zi_rt2 = pickle.loads(pkl)
+                with self.subTest(test="Is unpickled ZoneInfo"):
+                    self.assertIs(zi_rt, zi_rt2)
 
     def test_cache_miss(self):
-        zi_in = self.klass("Europe/Dublin")
-        pkl = pickle.dumps(zi_in)
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            with self.subTest(proto=proto):
+                zi_in = self.klass("Europe/Dublin")
+                pkl = pickle.dumps(zi_in, protocol=proto)
 
-        del zi_in
-        self.klass.clear_cache()  # Induce a cache miss
-        zi_rt = pickle.loads(pkl)
-        zi_rt2 = pickle.loads(pkl)
+                del zi_in
+                self.klass.clear_cache()  # Induce a cache miss
+                zi_rt = pickle.loads(pkl)
+                zi_rt2 = pickle.loads(pkl)
 
-        self.assertIs(zi_rt, zi_rt2)
+                self.assertIs(zi_rt, zi_rt2)
 
     def test_no_cache(self):
-        zi_no_cache = self.klass.no_cache("Europe/Dublin")
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            with self.subTest(proto=proto):
+                zi_no_cache = self.klass.no_cache("Europe/Dublin")
 
-        pkl = pickle.dumps(zi_no_cache)
-        zi_rt = pickle.loads(pkl)
+                pkl = pickle.dumps(zi_no_cache, protocol=proto)
+                zi_rt = pickle.loads(pkl)
 
-        with self.subTest(test="Not the pickled object"):
-            self.assertIsNot(zi_rt, zi_no_cache)
+                with self.subTest(test="Not the pickled object"):
+                    self.assertIsNot(zi_rt, zi_no_cache)
 
-        zi_rt2 = pickle.loads(pkl)
-        with self.subTest(test="Not a second unpickled object"):
-            self.assertIsNot(zi_rt, zi_rt2)
+                zi_rt2 = pickle.loads(pkl)
+                with self.subTest(test="Not a second unpickled object"):
+                    self.assertIsNot(zi_rt, zi_rt2)
 
-        zi_cache = self.klass("Europe/Dublin")
-        with self.subTest(test="Not a cached object"):
-            self.assertIsNot(zi_rt, zi_cache)
+                zi_cache = self.klass("Europe/Dublin")
+                with self.subTest(test="Not a cached object"):
+                    self.assertIsNot(zi_rt, zi_cache)
 
     def test_from_file(self):
         key = "Europe/Dublin"
@@ -1456,35 +1462,38 @@ class ZoneInfoPickleTest(TzPathUserMixin, ZoneInfoTestBase):
         ]
 
         for zi, test_name in test_cases:
-            with self.subTest(test_name=test_name):
-                with self.assertRaises(pickle.PicklingError):
-                    pickle.dumps(zi)
+            for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+                with self.subTest(test_name=test_name, proto=proto):
+                    with self.assertRaises(pickle.PicklingError):
+                        pickle.dumps(zi, protocol=proto)
 
     def test_pickle_after_from_file(self):
         # This may be a bit of paranoia, but this test is to ensure that no
         # global state is maintained in order to handle the pickle cache and
         # from_file behavior, and that it is possible to interweave the
         # constructors of each of these and pickling/unpickling without issues.
-        key = "Europe/Dublin"
-        zi = self.klass(key)
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            with self.subTest(proto=proto):
+                key = "Europe/Dublin"
+                zi = self.klass(key)
 
-        pkl_0 = pickle.dumps(zi)
-        zi_rt_0 = pickle.loads(pkl_0)
-        self.assertIs(zi, zi_rt_0)
+                pkl_0 = pickle.dumps(zi, protocol=proto)
+                zi_rt_0 = pickle.loads(pkl_0)
+                self.assertIs(zi, zi_rt_0)
 
-        with open(self.zoneinfo_data.path_from_key(key), "rb") as f:
-            zi_ff = self.klass.from_file(f, key=key)
+                with open(self.zoneinfo_data.path_from_key(key), "rb") as f:
+                    zi_ff = self.klass.from_file(f, key=key)
 
-        pkl_1 = pickle.dumps(zi)
-        zi_rt_1 = pickle.loads(pkl_1)
-        self.assertIs(zi, zi_rt_1)
+                pkl_1 = pickle.dumps(zi, protocol=proto)
+                zi_rt_1 = pickle.loads(pkl_1)
+                self.assertIs(zi, zi_rt_1)
 
-        with self.assertRaises(pickle.PicklingError):
-            pickle.dumps(zi_ff)
+                with self.assertRaises(pickle.PicklingError):
+                    pickle.dumps(zi_ff, protocol=proto)
 
-        pkl_2 = pickle.dumps(zi)
-        zi_rt_2 = pickle.loads(pkl_2)
-        self.assertIs(zi, zi_rt_2)
+                pkl_2 = pickle.dumps(zi, protocol=proto)
+                zi_rt_2 = pickle.loads(pkl_2)
+                self.assertIs(zi, zi_rt_2)
 
 
 class CZoneInfoPickleTest(ZoneInfoPickleTest):
diff --git a/Misc/NEWS.d/next/Tests/2021-10-22-19-44-13.bpo-45577.dSaNvK.rst b/Misc/NEWS.d/next/Tests/2021-10-22-19-44-13.bpo-45577.dSaNvK.rst
new file mode 100644
index 0000000..fc9783e
--- /dev/null
+++ b/Misc/NEWS.d/next/Tests/2021-10-22-19-44-13.bpo-45577.dSaNvK.rst
@@ -0,0 +1 @@
+Add subtests for all ``pickle`` protocols in ``test_zoneinfo``.