Add focused tie policy tests

tests/test_tie_policy.py

@@ -0,0 +1,156 @@
+"""Focused pytest coverage for tie_policy normalization and application."""
+
+from __future__ import annotations
+
+import pytest
+from music21 import note, stream
+from music21.tie import Tie
+
+from registral_dispersion.tie_policy import (
+    DEFAULT_TIE_POLICY,
+    TIE_POLICY_AS_IMPORTED,
+    TIE_POLICY_MERGE_TIES,
+    apply_tie_policy,
+    normalize_tie_policy,
+)
+
+
+# ---------------------------------------------------------------------------
+# normalize_tie_policy — defaults
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.parametrize(
+    "value",
+    [None, "", "   ", "\t\n"],
+)
+def test_normalize_tie_policy_defaults(value) -> None:
+    assert normalize_tie_policy(value) == DEFAULT_TIE_POLICY
+    assert normalize_tie_policy(value) == TIE_POLICY_AS_IMPORTED
+
+
+# ---------------------------------------------------------------------------
+# normalize_tie_policy — accepted aliases
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.parametrize(
+    ("value", "expected"),
+    [
+        ("as_imported", TIE_POLICY_AS_IMPORTED),
+        ("as imported", TIE_POLICY_AS_IMPORTED),
+        ("as-imported", TIE_POLICY_AS_IMPORTED),
+        ("MERGE-TIES", TIE_POLICY_MERGE_TIES),
+        ("merge ties", TIE_POLICY_MERGE_TIES),
+    ],
+)
+def test_normalize_tie_policy_accepted_aliases(value: str, expected: str) -> None:
+    assert normalize_tie_policy(value) == expected
+
+
+# ---------------------------------------------------------------------------
+# normalize_tie_policy — invalid
+# ---------------------------------------------------------------------------
+
+
+def test_normalize_tie_policy_rejects_unknown_value() -> None:
+    with pytest.raises(ValueError) as exc_info:
+        normalize_tie_policy("bogus_policy")
+    msg = str(exc_info.value)
+    assert "Unknown tie_policy" in msg
+    assert "bogus_policy" in msg
+    assert TIE_POLICY_AS_IMPORTED in msg
+    assert TIE_POLICY_MERGE_TIES in msg
+
+
+# ---------------------------------------------------------------------------
+# apply_tie_policy — as_imported
+# ---------------------------------------------------------------------------
+
+
+def test_apply_tie_policy_as_imported_returns_same_stream() -> None:
+    sc = stream.Score()
+    sc.insert(0, stream.Part())
+    result, warnings = apply_tie_policy(sc, TIE_POLICY_AS_IMPORTED)
+    assert result is sc
+    assert warnings == []
+
+
+# ---------------------------------------------------------------------------
+# apply_tie_policy — merge_ties success
+# ---------------------------------------------------------------------------
+
+
+def _score_with_simple_tie() -> stream.Score:
+    p = stream.Part()
+    n1 = note.Note("C4", quarterLength=1.0)
+    n2 = note.Note("C4", quarterLength=1.0)
+    n1.tie = Tie("start")
+    n2.tie = Tie("stop")
+    p.insert(0, n1)
+    p.insert(1, n2)
+    sc = stream.Score()
+    sc.insert(0, p)
+    return sc
+
+
+def test_apply_tie_policy_merge_ties_collapses_tied_notes() -> None:
+    sc = _score_with_simple_tie()
+    merged, warnings = apply_tie_policy(sc, TIE_POLICY_MERGE_TIES)
+    assert merged is not None
+    assert isinstance(warnings, list)
+    notes = list(merged.flatten().notes)
+    assert len(notes) == 1
+    assert float(notes[0].quarterLength) == pytest.approx(2.0)
+
+
+# ---------------------------------------------------------------------------
+# apply_tie_policy — stripTies exception fallback
+# ---------------------------------------------------------------------------
+
+
+class _StripTiesFailingScore:
+    def stripTies(self, inPlace: bool = False):
+        raise RuntimeError("simulated stripTies failure")
+
+
+def test_apply_tie_policy_merge_ties_strip_ties_failure_fallback() -> None:
+    fake = _StripTiesFailingScore()
+    result, warnings = apply_tie_policy(fake, TIE_POLICY_MERGE_TIES)
+    assert result is fake
+    assert len(warnings) == 1
+    assert "stripTies failed" in warnings[0]
+    assert "falling back to as_imported" in warnings[0]
+
+
+# ---------------------------------------------------------------------------
+# apply_tie_policy — residual tie metadata warning
+# ---------------------------------------------------------------------------
+
+
+class _NoteWithResidualTie:
+    tie = object()
+
+
+class _RecurseWithTiedNotes:
+    notes = [_NoteWithResidualTie()]
+
+
+class _MergedStreamWithResidualTies:
+    def recurse(self):
+        return _RecurseWithTiedNotes()
+
+
+class _StripTiesScoreWithResidualTies:
+    def stripTies(self, inPlace: bool = False):
+        return _MergedStreamWithResidualTies()
+
+
+def test_apply_tie_policy_merge_ties_warns_on_residual_tie_metadata() -> None:
+    fake = _StripTiesScoreWithResidualTies()
+    merged, warnings = apply_tie_policy(fake, TIE_POLICY_MERGE_TIES)
+    assert merged is not None
+    assert isinstance(merged, _MergedStreamWithResidualTies)
+    assert len(warnings) == 1
+    assert "still carry tie metadata" in warnings[0]
+    assert "interpret sustained durations with caution" in warnings[0]