chore: import upstream snapshot with attribution

tests/test_cluster.py

@@ -0,0 +1,100 @@
+import json
+import sys
+import networkx as nx
+from pathlib import Path
+from graphify.build import build_from_json
+from graphify.cluster import cluster, cohesion_score, remap_communities_to_previous, score_all
+
+FIXTURES = Path(__file__).parent / "fixtures"
+
+def make_graph():
+    return build_from_json(json.loads((FIXTURES / "extraction.json").read_text()))
+
+def test_cluster_returns_dict():
+    G = make_graph()
+    communities = cluster(G)
+    assert isinstance(communities, dict)
+
+def test_cluster_covers_all_nodes():
+    G = make_graph()
+    communities = cluster(G)
+    all_nodes = {n for nodes in communities.values() for n in nodes}
+    assert all_nodes == set(G.nodes)
+
+def test_cohesion_score_complete_graph():
+    G = nx.complete_graph(4)
+    G = nx.relabel_nodes(G, {i: str(i) for i in G.nodes})
+    score = cohesion_score(G, list(G.nodes))
+    assert score == 1.0
+
+def test_cohesion_score_single_node():
+    G = nx.Graph()
+    G.add_node("a")
+    score = cohesion_score(G, ["a"])
+    assert score == 1.0
+
+def test_cohesion_score_disconnected():
+    G = nx.Graph()
+    G.add_nodes_from(["a", "b", "c"])
+    score = cohesion_score(G, ["a", "b", "c"])
+    assert score == 0.0
+
+def test_cohesion_score_range():
+    G = make_graph()
+    communities = cluster(G)
+    for cid, nodes in communities.items():
+        score = cohesion_score(G, nodes)
+        assert 0.0 <= score <= 1.0
+
+def test_score_all_keys_match_communities():
+    G = make_graph()
+    communities = cluster(G)
+    scores = score_all(G, communities)
+    assert set(scores.keys()) == set(communities.keys())
+
+
+def test_cluster_does_not_write_to_stdout(capsys):
+    """Clustering should not emit ANSI escape codes or other output.
+
+    graspologic's leiden() can emit ANSI escape sequences that break
+    PowerShell 5.1's scroll buffer on Windows (issue #19). The output
+    suppression in _partition() should prevent any output from leaking.
+    """
+    G = make_graph()
+    cluster(G)
+    captured = capsys.readouterr()
+    assert captured.out == "", f"cluster() wrote to stdout: {captured.out!r}"
+
+
+def test_cluster_does_not_write_to_stderr(capsys):
+    """Same as above but for stderr — ANSI codes can go to either stream."""
+    G = make_graph()
+    cluster(G)
+    captured = capsys.readouterr()
+    # Allow logging output (starts with [graphify]) but no raw ANSI codes
+    for line in captured.err.splitlines():
+        assert "\x1b" not in line, f"cluster() wrote ANSI to stderr: {line!r}"
+
+
+def test_remap_communities_to_previous_reuses_old_ids():
+    communities = {
+        10: ["a", "b", "c"],
+        11: ["d", "e"],
+    }
+    previous = {"a": 5, "b": 5, "c": 5, "d": 1, "e": 1}
+    remapped = remap_communities_to_previous(communities, previous)
+    assert set(remapped.keys()) == {1, 5}
+    assert remapped[5] == ["a", "b", "c"]
+    assert remapped[1] == ["d", "e"]
+
+
+def test_remap_communities_to_previous_assigns_deterministic_new_ids():
+    communities = {
+        7: ["x", "y", "z"],
+        8: ["m"],
+    }
+    previous = {"a": 3}
+    remapped = remap_communities_to_previous(communities, previous)
+    assert list(remapped.keys()) == [0, 1]
+    assert remapped[0] == ["x", "y", "z"]
+    assert remapped[1] == ["m"]