test: relocate service-layer tests to tests/services/

Mirrors the source layout (core/services split) so unit/ holds core-only
tests and services get their own home.

tests/services/test_persistence.py

@@ -0,0 +1,107 @@
+"""Unit tests for the persistence service — JSON round-trip."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+import pytest
+from pydantic import ValidationError
+
+from otko.core import (
+    Concrete02,
+    ElasticBeamColumn,
+    ElasticSection,
+    LinearTimeSeries,
+    NodalLoad,
+    Node,
+    PlainLoadPattern,
+    Project,
+    ProjectMeta,
+    Steel01,
+    TrussElement,
+    UnitSystem,
+)
+from otko.services import PROJECT_FILE_SUFFIX, load_project, save_project
+
+
+def _sample_project() -> Project:
+    return Project(
+        meta=ProjectMeta(name="Sample", author="Ozan", units=UnitSystem.SI_M_N),
+        ndm=3,
+        ndf=6,
+        nodes=[
+            Node(id=1, coords=(0, 0, 0), restraint=(True,) * 6),
+            Node(id=2, coords=(0, 0, 3.0)),
+        ],
+        materials=[
+            Steel01(id=1, Fy=420e6, E0=200e9, b=0.01),
+            Concrete02(
+                id=2,
+                fpc=-30e6,
+                epsc0=-0.002,
+                fpcu=-15e6,
+                epsU=-0.005,
+                ft=3e6,
+                Ets=2e9,
+                **{"lambda": 0.1},
+            ),
+        ],
+        sections=[ElasticSection(id=1, E=200e9, A=0.01, Iz=8.33e-6, Iy=8.33e-6, G=80e9, J=1e-6)],
+        elements=[
+            ElasticBeamColumn(id=1, nodes=(1, 2), section_id=1, geom_transf="PDelta"),
+            TrussElement(id=2, nodes=(1, 2), area=1e-3, material_id=1),
+        ],
+        time_series=[LinearTimeSeries(id=1, factor=1.0)],
+        load_patterns=[
+            PlainLoadPattern(
+                id=1,
+                time_series_id=1,
+                nodal_loads=[NodalLoad(node_id=2, forces=(0, 0, -10e3, 0, 0, 0))],
+            )
+        ],
+    )
+
+
+def test_round_trip_preserves_everything(tmp_path: Path) -> None:
+    original = _sample_project()
+    target = save_project(original, tmp_path / "model")
+    assert target.suffix == PROJECT_FILE_SUFFIX
+    assert target.exists()
+
+    restored = load_project(target)
+    assert restored.model_dump(by_alias=True) == original.model_dump(by_alias=True)
+
+
+def test_save_appends_suffix_when_missing(tmp_path: Path) -> None:
+    p = Project()
+    out = save_project(p, tmp_path / "no_extension")
+    assert out.suffix == PROJECT_FILE_SUFFIX
+
+
+def test_save_keeps_existing_suffix(tmp_path: Path) -> None:
+    p = Project()
+    out = save_project(p, tmp_path / "with_ext.osmodel")
+    assert out.name == "with_ext.osmodel"
+
+
+def test_load_missing_file_raises() -> None:
+    with pytest.raises(FileNotFoundError):
+        load_project("/no/such/path/x.osmodel")
+
+
+def test_load_corrupt_file_raises_validation_error(tmp_path: Path) -> None:
+    bad = tmp_path / "bad.osmodel"
+    bad.write_text('{"ndm": 2, "ndf": 6}', encoding="utf-8")  # invalid combo
+    with pytest.raises(ValidationError):
+        load_project(bad)
+
+
+def test_polymorphic_collection_dispatches_correctly(tmp_path: Path) -> None:
+    """Materials list must restore as Steel01 + Concrete02 — not generic Entity."""
+    original = _sample_project()
+    out = save_project(original, tmp_path / "x")
+    restored = load_project(out)
+    assert isinstance(restored.materials[0], Steel01)
+    assert isinstance(restored.materials[1], Concrete02)
+    assert isinstance(restored.elements[0], ElasticBeamColumn)
+    assert isinstance(restored.elements[1], TrussElement)