Empty graph tests fail due to leftover data from module-scoped fixtures

[mykola-pereyma]

Describe the bug

test_louvain_communities_empty_graph and test_pagerank_empty_graph integration tests fail because prior test methods in the same module sync data to Neptune via the neptune_graph fixture (module-scoped, autouse), and that data is never cleaned up between individual test methods. The empty graph tests create a local empty graph and pass it to the algorithm with backend='neptune', but the Neptune instance still contains nodes and edges from earlier tests.

To Reproduce

1. Set NETWORKX_GRAPH_ID to a running Neptune Analytics graph
2. Run python -m pytest integ_test/test_algo_louvain.py -v --tb=short
3. Observe test_louvain_communities_empty_graph fails with assert 2 == 0 (gets 2 communities from leftover data)
4. Run python -m pytest integ_test/test_algo_page_rank.py -v --tb=short
5. Observe test_pagerank_empty_graph fails with assert 6 == 0 (gets 6 node scores from leftover data)

Expected behavior

Both empty graph tests should return empty results:

• test_louvain_communities_empty_graph: len(result) == 0
• test_pagerank_empty_graph: len(r) == 0

Screenshots

FAILED integ_test/test_algo_louvain.py::TestLouvain::test_louvain_communities_empty_graph
AssertionError: assert 2 == 0
where 2 = len([{'A', 'B', 'C'}, {'D', 'E', 'F'}])

FAILED integ_test/test_algo_page_rank.py::TestPageRank::test_pagerank_empty_graph
AssertionError: assert 6 == 0
where 6 = len({'A': 0.0291, 'B': 0.0538, 'C': 0.3152, 'D': 0.2962, ...})

Desktop (please complete the following information):

• OS: macOS
• Version: nx-neptune 0.5.0

Additional context

Root cause: neptune_graph fixture is scope='module' and autouse=True. Earlier test methods use test_graph/test_digraph fixtures that sync nodes (A-F) and edges to Neptune. No cleanup happens between test methods. The empty graph tests run last by source order and inherit the Neptune state.

Suggested fix: add a clear_graph() call before the empty/single-node tests, either via a fixture or at the start of the test method.

Affected tests:

• integ_test/test_algo_louvain.py::TestLouvain::test_louvain_communities_empty_graph
• integ_test/test_algo_page_rank.py::TestPageRank::test_pagerank_empty_graph