refactor(ata): move fixed-form greedy assembly ownership to Rust

tests/test_test_form_rust_ownership.py

@@ -0,0 +1,42 @@
+"""Fail-first ownership contracts for fixed-form maximum-information assembly."""
+
+from __future__ import annotations
+
+import numpy as np
+
+import fast_mlsirm._core as core
+from fast_mlsirm.test_design import assemble_test_form
+
+
+def test_public_test_form_assembly_delegates_selection_to_rust(monkeypatch) -> None:
+    """Ordering, exclusion, and content-feasibility decisions come from Rust."""
+    information = np.array([1.0, 4.0, 3.0, 2.0], dtype=np.float64)
+    content = np.array(["A", "A", "B", "B"], dtype=object)
+    exclude = np.array([3], dtype=np.int64)
+    information_before = information.copy()
+    content_before = content.copy()
+    exclude_before = exclude.copy()
+    calls: list[tuple[tuple[object, ...], dict[str, object]]] = []
+
+    def fake_assemble(*args: object, **kwargs: object) -> list[int]:
+        calls.append((args, kwargs))
+        # A deliberately different valid form from the current Python greedy
+        # result proves public result ownership rather than mere helper reuse.
+        return [2, 0]
+
+    monkeypatch.setattr(core, "assemble_test_form_greedy", fake_assemble, raising=False)
+
+    selected = assemble_test_form(
+        information,
+        length=2,
+        content=content,
+        min_per_content={"B": 1},
+        max_per_content={"A": 1},
+        exclude=exclude,
+    )
+
+    assert len(calls) == 1
+    assert np.array_equal(selected, np.array([2, 0], dtype=np.int64))
+    assert np.array_equal(information, information_before)
+    assert np.array_equal(content, content_before)
+    assert np.array_equal(exclude, exclude_before)