Test topology pruning (#179)

Test topology pruning

tests/test_topology_prune.py

@@ -0,0 +1,75 @@
+"""
+Tests topology.
+"""
+import unittest
+from sklearn.base import BaseEstimator, TransformerMixin
+from sklearn.pipeline import make_pipeline
+from sklearn import datasets
+
+from skl2onnx.common.data_types import FloatTensorType
+from skl2onnx import convert_sklearn, update_registered_converter
+from skl2onnx.algebra.onnx_ops import OnnxIdentity
+
+
+class IdentityTransformer(BaseEstimator, TransformerMixin):
+    def __init__(self):
+        TransformerMixin.__init__(self)
+        BaseEstimator.__init__(self)
+
+    def fit(self, X, y, sample_weight=None):
+        return self
+
+    def transform(self, X):
+        return X
+
+
+class identity(IdentityTransformer):
+
+    def __init__(self):
+        IdentityTransformer.__init__(self)
+
+
+def dummy_shape_calculator(operator):
+    op_input = operator.inputs[0]
+    operator.outputs[0].type = FloatTensorType(op_input.type.shape)
+
+
+def dummy_converter(scope, operator, container):
+    X = operator.inputs[0]
+    out = operator.outputs
+
+    id1 = OnnxIdentity(X)
+    id2 = OnnxIdentity(id1, output_names=out[1:])
+    id2.add_to(scope, container)
+
+
+class TestTopologyPrune(unittest.TestCase):
+
+    def test_dummy_identity(self):
+
+        digits = datasets.load_digits(n_class=6)
+        Xd = digits.data[:20]
+        yd = digits.target[:20]
+        n_samples, n_features = Xd.shape
+
+        idtr = make_pipeline(IdentityTransformer(), identity())
+        idtr.fit(Xd, yd)
+
+        update_registered_converter(IdentityTransformer, "IdentityTransformer",
+                                    dummy_shape_calculator, dummy_converter)
+        update_registered_converter(identity, "identity",
+                                    dummy_shape_calculator, dummy_converter)
+
+        model_onnx = convert_sklearn(
+            idtr,
+            "idtr",
+            [("input", FloatTensorType([1, Xd.shape[1]]))],
+        )
+
+        idnode = [node for node in model_onnx.graph.node
+                  if node.op_type == "Identity"]
+        assert len(idnode) == 2
+
+
+if __name__ == "__main__":
+    unittest.main()