Refactor out different test cases to separate tests (#1176)

The previous solution had two test conditions (strict and not strict)
and several scikit-learn versions, because of two distinct changes
within scikit-learn (the removal of min_impurity_split in 1.0, and the
restructuring of public/private models in 0.24).
I refactored out the separate test cases to greatly simplify the
individual tests, and I added a test case for scikit-learn>=1.0,
which was previously not covered.

Author: PGijsbers

tests/test_flows/test_flow_functions.py

@@ -324,32 +324,55 @@ def test_get_flow_reinstantiate_model_no_extension(self):
         )
 
     @unittest.skipIf(
-        LooseVersion(sklearn.__version__) == "0.19.1", reason="Target flow is from sklearn 0.19.1"
+        LooseVersion(sklearn.__version__) == "0.19.1",
+        reason="Requires scikit-learn!=0.19.1, because target flow is from that version.",
     )
-    def test_get_flow_reinstantiate_model_wrong_version(self):
-        # Note that CI does not test against 0.19.1.
+    def test_get_flow_with_reinstantiate_strict_with_wrong_version_raises_exception(self):
         openml.config.server = self.production_server
-        _, sklearn_major, _ = LooseVersion(sklearn.__version__).version[:3]
-        if sklearn_major > 23:
-            flow = 18587  # 18687, 18725 --- flows building random forest on >= 0.23
-            flow_sklearn_version = "0.23.1"
-        else:
-            flow = 8175
-            flow_sklearn_version = "0.19.1"
-        expected = (
-            "Trying to deserialize a model with dependency "
-            "sklearn=={} not satisfied.".format(flow_sklearn_version)
-        )
+        flow = 8175
+        expected = "Trying to deserialize a model with dependency sklearn==0.19.1 not satisfied."
         self.assertRaisesRegex(
-            ValueError, expected, openml.flows.get_flow, flow_id=flow, reinstantiate=True
+            ValueError,
+            expected,
+            openml.flows.get_flow,
+            flow_id=flow,
+            reinstantiate=True,
+            strict_version=True,
         )
-        if LooseVersion(sklearn.__version__) > "0.19.1":
-            # 0.18 actually can't deserialize this because of incompatibility
-            flow = openml.flows.get_flow(flow_id=flow, reinstantiate=True, strict_version=False)
-            # ensure that a new flow was created
-            assert flow.flow_id is None
-            assert "sklearn==0.19.1" not in flow.dependencies
-            assert "sklearn>=0.19.1" not in flow.dependencies
+
+    @unittest.skipIf(
+        LooseVersion(sklearn.__version__) < "1" and LooseVersion(sklearn.__version__) != "1.0.0",
+        reason="Requires scikit-learn < 1.0.1."
+        # Because scikit-learn dropped min_impurity_split hyperparameter in 1.0,
+        # and the requested flow is from 1.0.0 exactly.
+    )
+    def test_get_flow_reinstantiate_flow_not_strict_post_1(self):
+        openml.config.server = self.production_server
+        flow = openml.flows.get_flow(flow_id=19190, reinstantiate=True, strict_version=False)
+        assert flow.flow_id is None
+        assert "sklearn==1.0.0" not in flow.dependencies
+
+    @unittest.skipIf(
+        (LooseVersion(sklearn.__version__) < "0.23.2")
+        or ("1.0" < LooseVersion(sklearn.__version__)),
+        reason="Requires scikit-learn 0.23.2 or ~0.24."
+        # Because these still have min_impurity_split, but with new scikit-learn module structure."
+    )
+    def test_get_flow_reinstantiate_flow_not_strict_023_and_024(self):
+        openml.config.server = self.production_server
+        flow = openml.flows.get_flow(flow_id=18587, reinstantiate=True, strict_version=False)
+        assert flow.flow_id is None
+        assert "sklearn==0.23.1" not in flow.dependencies
+
+    @unittest.skipIf(
+        "0.23" < LooseVersion(sklearn.__version__),
+        reason="Requires scikit-learn<=0.23, because the scikit-learn module structure changed.",
+    )
+    def test_get_flow_reinstantiate_flow_not_strict_pre_023(self):
+        openml.config.server = self.production_server
+        flow = openml.flows.get_flow(flow_id=8175, reinstantiate=True, strict_version=False)
+        assert flow.flow_id is None
+        assert "sklearn==0.19.1" not in flow.dependencies
 
     def test_get_flow_id(self):
         if self.long_version: