Created initial list of simple Graph creation tests for nx compatibility

python/cugraph/cugraph/tests/test_nx_compatibility.py

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+# Copyright (c) 2022, NVIDIA CORPORATION.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+# Temporarily suppress warnings till networkX fixes deprecation warnings
+# (Using or importing the ABCs from 'collections' instead of from
+# 'collections.abc' is deprecated, and in 3.8 it will stop working) for
+# python 3.7.  Also, this import networkx needs to be relocated in the
+# third-party group once this gets fixed.
+import pytest
+from cugraph.tests import utils
+
+import networkx as nx
+
+
+def test_nx_gbuilder():
+
+    # Create an empty graph
+    G = nx.Graph()
+    assert G.number_of_edges() == 0
+    assert G.number_of_nodes() == 0
+
+    # Add a node
+    G.add_node(1)
+    assert G.number_of_edges() == 0
+    assert G.number_of_nodes() == 1
+
+    # Add some edges
+    G.add_edges_from([(1, 2), (1, 3)])
+    assert G.number_of_edges() == 2
+    assert G.number_of_nodes() == 3
+
+    # Add some duplicates
+    G.add_edges_from([(1, 2), (1, 3)])
+    G.add_node(1)
+    G.add_edge(1, 2)
+    assert G.number_of_edges() == 2
+    assert G.number_of_nodes() == 3
+
+    # Add nodes with a property from a list
+    G.add_nodes_from([(4, {"color": "red"}), (5, {"color": "green"}), ])
+    assert G.nodes[4]["color"] == "red"
+
+    G.add_node("spam")        # adds node "spam"
+    G.add_nodes_from("spam")  # adds 4 nodes: 's', 'p', 'a', 'm'
+    G.add_edge(3, 'm')
+    assert G.number_of_edges() == 3
+    assert G.number_of_nodes() == 10
+    assert list(G.nodes) == [1, 2, 3, 4, 5, 'spam', 's', 'p', 'a', 'm']
+    # remove nodes
+    G.remove_node(2)
+    G.remove_nodes_from("spam")
+    assert list(G.nodes) == [1, 3, 4, 5, 'spam']
+    G.remove_edge(1, 3)
+
+    # Access edge attributes
+    G = nx.Graph([(1, 2, {"color": "yellow"})])
+    assert G[1][2] == {'color': 'yellow'}
+    assert G.edges[1, 2] == {'color': 'yellow'}
+
+
+def test_nx_graph_functions():
+    # test adjacency
+    FG = nx.Graph()
+    FG.add_weighted_edges_from([(1, 2, 0.125), (1, 3, 0.75),
+                                (2, 4, 1.2), (3, 4, 0.375)])
+    for n, nbrs in FG.adj.items():
+        for nbr, eattr in nbrs.items():
+            wt = eattr['weight']
+            if wt < 0.5:
+                assert FG[n][nbr]['weight'] < 0.5
+    # accessing graph edges
+    for (u, v, wt) in FG.edges.data('weight'):
+        if wt < 0.5:
+            assert FG[u][v]['weight'] <= 0.5
+        else:
+            assert FG[u][v]['weight'] > 0.5
+
+
+def test_nx_analysis():
+    G = nx.Graph()
+    G.add_edges_from([(1, 2), (1, 3)])
+    G.add_node("spam")       # adds node "spam"
+    assert list(nx.connected_components(G)) == [{1, 2, 3}, {'spam'}]
+    assert sorted(d for n, d in G.degree()) == [0, 1, 1, 2]
+    assert nx.clustering(G) == {1: 0, 2: 0, 3: 0, 'spam': 0}
+    assert list(nx.bfs_edges(G, 1)) == [(1, 2), (1, 3)]
+
+
+@pytest.mark.parametrize(
+    "graph_file",
+    [utils.RAPIDS_DATASET_ROOT_DIR_PATH/"dolphins.csv"])
+def test_with_dolphins(graph_file):
+
+    df = utils.read_csv_for_nx(graph_file, read_weights_in_sp=True)
+    G = nx.from_pandas_edgelist(df, create_using=nx.Graph(),
+                                source="0", target="1", edge_attr="weight")
+
+    assert G.degree(0) == 6
+    assert G.degree(14) == 12
+    assert G.degree(15) == 7
+    assert G.degree(40) == 8
+    assert G.degree(42) == 6
+    assert G.degree(47) == 6
+    assert G.degree(17) == 9