Detects and adds isolates when creating a plc.SGGraph, removes specia…

…l case testing and skipped tests from prior PR needed due to the bug this PR fixes.

ci/test_python.sh

@@ -111,11 +111,6 @@ popd
 rapids-logger "pytest networkx using nx-cugraph backend"
 pushd python/nx-cugraph
 ./run_nx_tests.sh
-# Individually run tests that are skipped above b/c they may run out of memory
-PYTEST_NO_SKIP=True ./run_nx_tests.sh --cov-append -k "TestDAG and test_antichains"
-PYTEST_NO_SKIP=True ./run_nx_tests.sh --cov-append -k "TestMultiDiGraph_DAGLCA and test_all_pairs_lca_pairs_without_lca"
-PYTEST_NO_SKIP=True ./run_nx_tests.sh --cov-append -k "TestDAGLCA and test_all_pairs_lca_pairs_without_lca"
-PYTEST_NO_SKIP=True ./run_nx_tests.sh --cov-append -k "TestEfficiency and test_using_ego_graph"
 # run_nx_tests.sh outputs coverage data, so check that total coverage is >0.0%
 # in case nx-cugraph failed to load but fallback mode allowed the run to pass.
 _coverage=$(coverage report|grep "^TOTAL")

python/nx-cugraph/nx_cugraph/classes/graph.py

@@ -65,6 +65,7 @@ class Graph:
     key_to_id: dict[NodeKey, IndexValue] | None
     _id_to_key: list[NodeKey] | None
     _N: int
+    _node_ids: cp.ndarray[IndexValue] | None  # holds plc.SGGraph.vertices_array data
 
     # Used by graph._get_plc_graph
     _plc_type_map: ClassVar[dict[np.dtype, np.dtype]] = {
@@ -116,6 +117,7 @@ def from_coo(
         new_graph.key_to_id = None if key_to_id is None else dict(key_to_id)
         new_graph._id_to_key = None if id_to_key is None else list(id_to_key)
         new_graph._N = op.index(N)  # Ensure N is integral
+        new_graph._node_ids = None
         new_graph.graph = new_graph.graph_attr_dict_factory()
         new_graph.graph.update(attr)
         size = new_graph.src_indices.size
@@ -405,6 +407,7 @@ def clear(self) -> None:
         self.src_indices = cp.empty(0, self.src_indices.dtype)
         self.dst_indices = cp.empty(0, self.dst_indices.dtype)
         self._N = 0
+        self._node_ids = None
         self.key_to_id = None
         self._id_to_key = None
 
@@ -637,6 +640,18 @@ def _get_plc_graph(
         dst_indices = self.dst_indices
         if switch_indices:
             src_indices, dst_indices = dst_indices, src_indices
+
+        # If the graph contains isolates, plc.SGGraph() must be passed a
+        # value for vertices_array that contains every vertex ID, since the
+        # src/dst_indices arrays will not contain IDs for isolates.
+        all_node_ids = cp.arange(self._N, dtype=index_dtype)
+        isolates = cp.setdiff1d(cp.setdiff1d(all_node_ids, src_indices), dst_indices)
+        if len(isolates) == 0:
+            all_node_ids = None
+        # like self.src/dst_indices, the _node_ids array must be maintained for
+        # the lifetime of the plc.SGGraph
+        self._node_ids = all_node_ids
+
         return plc.SGGraph(
             resource_handle=plc.ResourceHandle(),
             graph_properties=plc.GraphProperties(
@@ -649,6 +664,7 @@ def _get_plc_graph(
             store_transposed=store_transposed,
             renumber=False,
             do_expensive_check=False,
+            vertices_array=self._node_ids,
         )
 
     def _sort_edge_indices(self, primary="src"):

python/nx-cugraph/nx_cugraph/interface.py

@@ -242,20 +242,9 @@ def key(testpath):
                     )
 
         too_slow = "Too slow to run"
-        maybe_oom = "out of memory in CI"
         skip = {
             key("test_tree_isomorphism.py:test_positive"): too_slow,
             key("test_tree_isomorphism.py:test_negative"): too_slow,
-            key("test_efficiency.py:TestEfficiency.test_using_ego_graph"): maybe_oom,
-            key("test_dag.py:TestDAG.test_antichains"): maybe_oom,
-            key(
-                "test_lowest_common_ancestors.py:"
-                "TestDAGLCA.test_all_pairs_lca_pairs_without_lca"
-            ): maybe_oom,
-            key(
-                "test_lowest_common_ancestors.py:"
-                "TestMultiDiGraph_DAGLCA.test_all_pairs_lca_pairs_without_lca"
-            ): maybe_oom,
             # These repeatedly call `bfs_layers`, which converts the graph every call
             key(
                 "test_vf2pp.py:TestGraphISOVF2pp.test_custom_graph2_different_labels"