edit tests to reference most recent pickle protocols

lib/iris/tests/integration/test_pickle.py

@@ -9,50 +9,43 @@
 import iris.tests as tests  # isort:skip
 
 import pickle
+import pytest
 
 import iris
 
 
-class Common:
-    def pickle_cube(self, protocol):
-        # Ensure that data proxies are pickleable.
-        cube = iris.load(self.path)[0]
-        with self.temp_filename(".pkl") as filename:
-            with open(filename, "wb") as f:
-                pickle.dump(cube, f, protocol)
-            with open(filename, "rb") as f:
-                ncube = pickle.load(f)
-        self.assertEqual(ncube, cube)
+MIN_PICKLE_PROTOCOL = 4
+TESTED_PROTOCOLS = list(range(MIN_PICKLE_PROTOCOL, pickle.HIGHEST_PROTOCOL + 1))
 
-    def test_protocol_0(self):
-        self.pickle_cube(0)
-
-    def test_protocol_1(self):
-        self.pickle_cube(1)
-
-    def test_protocol_2(self):
-        self.pickle_cube(2)
+def pickle_cube(path, protocol):
+    # Ensure that data proxies are pickleable.
+    cube = iris.load(path)[0]
+    with self.temp_filename(".pkl") as filename:
+        with open(filename, "wb") as f:
+            pickle.dump(cube, f, protocol)
+        with open(filename, "rb") as f:
+            ncube = pickle.load(f)
+    assert ncube == cube
 
 
+@pytest.mark.parametrize("protocol", TESTED_PROTOCOLS)
 @tests.skip_data
-class test_netcdf(Common, tests.IrisTest):
-    def setUp(self):
-        self.path = tests.get_data_path(
-            ("NetCDF", "global", "xyt", "SMALL_hires_wind_u_for_ipcc4.nc")
-        )
+def test_netcdf(protocol):
+    path = tests.get_data_path(
+        ("NetCDF", "global", "xyt", "SMALL_hires_wind_u_for_ipcc4.nc")
+    )
+    pickle_cube(path, protocol)
 
 
+@pytest.mark.parametrize("protocol", TESTED_PROTOCOLS)
 @tests.skip_data
-class test_pp(Common, tests.IrisTest):
-    def setUp(self):
-        self.path = tests.get_data_path(("PP", "aPPglob1", "global.pp"))
+def test_pp(protocol):
+    path = tests.get_data_path(("PP", "aPPglob1", "global.pp"))
+    pickle_cube(path, protocol)
 
 
+@pytest.mark.parametrize("protocol", TESTED_PROTOCOLS)
 @tests.skip_data
-class test_ff(Common, tests.IrisTest):
-    def setUp(self):
-        self.path = tests.get_data_path(("FF", "n48_multi_field"))
-
-
-if __name__ == "__main__":
-    tests.main()
+def test_ff(protocol):
+    self.path = tests.get_data_path(("FF", "n48_multi_field"))
+    pickle_cube(path, protocol)