Add optional dependencies for development and update .gitignore

- Added `.DS_Store` to `.gitignore` to prevent macOS system files from being tracked.
- Introduced optional development dependencies in `pyproject.toml`, including `pytest` and `responses`, to facilitate testing and development.
- Updated `uv.lock` with new package dependencies and versions for improved compatibility and functionality.
- Created new test files `conftest.py` and `test_view.py` to establish testing fixtures and implement unit tests for the `ModelView` class.

tests/conftest.py

@@ -0,0 +1,8 @@
+from pathlib import Path
+
+FIXTURES = Path(__file__).parent / "fixtures"
+
+
+def load(device: str, name: str = "config.conf") -> str:
+    """Read a device config fixture from tests/fixtures/<device>/<name>."""
+    return (FIXTURES / device / name).read_text(encoding="utf-8")

tests/test_view.py

@@ -0,0 +1,72 @@
+import json
+
+import pytest
+
+from oxi.conf import ModelView
+from oxi.interfaces.contract import Interfaces, System
+
+
+@pytest.fixture
+def system_view():
+    system = System(model="RB951", serial_number="ABC123", version="7.12")
+    return ModelView(system)
+
+
+@pytest.fixture
+def interfaces_view():
+    items = [
+        Interfaces(interface="eth0", ip_address="192.168.1.1", mask=24),
+        Interfaces(interface="eth1", description="uplink"),
+    ]
+    return ModelView(items)
+
+
+class TestSingleModelView:
+    def test_attribute_proxy(self, system_view):
+        assert system_view.model == "RB951"
+        assert system_view.serial_number == "ABC123"
+
+    def test_dump(self, system_view):
+        assert system_view.dump() == {
+            "model": "RB951",
+            "serial_number": "ABC123",
+            "version": "7.12",
+        }
+
+    def test_dump_json(self, system_view):
+        assert json.loads(system_view.dump_json())["model"] == "RB951"
+
+    def test_iter_raises(self, system_view):
+        with pytest.raises(TypeError):
+            iter(system_view)
+
+    def test_len_raises(self, system_view):
+        with pytest.raises(TypeError):
+            len(system_view)
+
+    def test_getitem_raises(self, system_view):
+        with pytest.raises(TypeError):
+            system_view[0]
+
+
+class TestListModelView:
+    def test_len(self, interfaces_view):
+        assert len(interfaces_view) == 2
+
+    def test_iter(self, interfaces_view):
+        names = [iface.name for iface in interfaces_view]
+        assert names == ["eth0", "eth1"]
+
+    def test_getitem(self, interfaces_view):
+        assert interfaces_view[0].name == "eth0"
+
+    def test_slice(self, interfaces_view):
+        assert len(interfaces_view[:1]) == 1
+
+    def test_dump_uses_aliases(self, interfaces_view):
+        dumped = interfaces_view.dump()
+        assert dumped[0]["interface"] == "eth0"
+
+    def test_dump_json_keeps_unicode(self):
+        view = ModelView([Interfaces(interface="eth0", description="Дом")])
+        assert "Дом" in view.dump_json()