tests: add test helper to compare digraphs

- add test to check that the helper is working

tests/conftest.py

@@ -0,0 +1,29 @@
+"""PyTest configuration file"""
+import networkx as nx
+import networkx.algorithms.isomorphism as iso
+import pytest
+
+
+class TestHelpers:
+    """Class allowing to pass helper functions to tests"""
+
+    @staticmethod
+    def digraphs_are_equivalent(reference: nx.DiGraph, to_compare: nx.DiGraph):
+        """Check that two digraphs are equivalent without modifications"""
+        # edge_match is a copy of node_match
+        edge_matcher = iso.categorical_node_match("input_idx", None)
+        node_matcher = iso.categorical_node_match("content", None)
+        graphs_are_isomorphic = nx.is_isomorphic(
+            reference,
+            to_compare,
+            node_match=node_matcher,
+            edge_match=edge_matcher,
+        )
+
+        return graphs_are_isomorphic
+
+
+@pytest.fixture
+def test_helpers():
+    """Fixture to return the static helper class"""
+    return TestHelpers

tests/helpers/test_conftest.py

@@ -0,0 +1,71 @@
+"""Test file for conftest helper functions"""
+import networkx as nx
+
+
+def test_digraphs_are_equivalent(test_helpers):
+    """Function to test digraphs_are_equivalent helper function"""
+
+    class TestNode:
+        """Dummy test node"""
+
+        computation: str
+
+        def __init__(self, computation: str) -> None:
+            self.computation = computation
+
+        def __hash__(self) -> int:
+            return self.computation.__hash__()
+
+        def __eq__(self, other) -> bool:
+            return self.computation == other.computation
+
+    g_1 = nx.DiGraph()
+    g_2 = nx.DiGraph()
+
+    t_0 = TestNode("Add")
+    t_1 = TestNode("Mul")
+    t_2 = TestNode("TLU")
+
+    g_1.add_edge(t_0, t_2, input_idx=0)
+    g_1.add_edge(t_1, t_2, input_idx=1)
+
+    # This updates the nodes attributes in the graph
+    for node in g_1:
+        g_1.add_node(node, content=node)
+
+    t0p = TestNode("Add")
+    t1p = TestNode("Mul")
+    t2p = TestNode("TLU")
+
+    g_2.add_edge(t1p, t2p, input_idx=1)
+    g_2.add_edge(t0p, t2p, input_idx=0)
+
+    # This updates the nodes attributes in the graph
+    for node in g_2:
+        g_2.add_node(node, content=node)
+
+    bad_g2 = nx.DiGraph()
+
+    bad_t0 = TestNode("Not Add")
+
+    bad_g2.add_edge(bad_t0, t_2, input_idx=0)
+    bad_g2.add_edge(t_1, t_2, input_idx=1)
+
+    # This updates the nodes attributes in the graph
+    for node in bad_g2:
+        bad_g2.add_node(node, content=node)
+
+    bad_g3 = nx.DiGraph()
+
+    bad_g3.add_edge(t_0, t_2, input_idx=1)
+    bad_g3.add_edge(t_1, t_2, input_idx=0)
+
+    # This updates the nodes attributes in the graph
+    for node in bad_g3:
+        bad_g3.add_node(node, content=node)
+
+    assert test_helpers.digraphs_are_equivalent(g_1, g_2), "Graphs should be equivalent"
+    assert not test_helpers.digraphs_are_equivalent(g_1, bad_g2), "Graphs should not be equivalent"
+    assert not test_helpers.digraphs_are_equivalent(g_2, bad_g2), "Graphs should not be equivalent"
+    assert not test_helpers.digraphs_are_equivalent(g_1, bad_g3), "Graphs should not be equivalent"
+    assert not test_helpers.digraphs_are_equivalent(g_2, bad_g3), "Graphs should not be equivalent"