adds StateManager tests

tests/data_service/test_state_manager.py

@@ -0,0 +1,142 @@
+import json
+from pathlib import Path
+from typing import Any
+
+from pytest import LogCaptureFixture
+
+import pydase
+import pydase.units as u
+from pydase.data_service.state_manager import StateManager
+
+
+class Service(pydase.DataService):
+    def __init__(self, **kwargs: Any) -> None:
+        self.some_unit: u.Quantity = 1.2 * u.units.A
+        self.some_float = 1.0
+        self._name = "Service"
+        super().__init__(**kwargs)
+
+    @property
+    def name(self) -> str:
+        return self._name
+
+
+CURRENT_STATE = {
+    "name": {
+        "type": "str",
+        "value": "Service",
+        "readonly": True,
+        "doc": None,
+    },
+    "some_float": {
+        "type": "float",
+        "value": 1.0,
+        "readonly": False,
+        "doc": None,
+    },
+    "some_unit": {
+        "type": "Quantity",
+        "value": {"magnitude": 1.2, "unit": "A"},
+        "readonly": False,
+        "doc": None,
+    },
+}
+
+LOAD_STATE = {
+    "name": {
+        "type": "str",
+        "value": "Service",
+        "readonly": True,
+        "doc": None,
+    },
+    "some_float": {
+        "type": "int",
+        "value": 1,
+        "readonly": False,
+        "doc": None,
+    },
+    "some_unit": {
+        "type": "Quantity",
+        "value": {"magnitude": 12.0, "unit": "A"},
+        "readonly": False,
+        "doc": None,
+    },
+}
+
+
+def test_save_state(tmp_path: Path):
+    # Create a StateManager instance with a temporary file
+    file = tmp_path / "test_state.json"
+    manager = StateManager(service=Service(), filename=str(file))
+
+    # Trigger the saving action
+    manager.save_state()
+
+    # Now check that the file was written correctly
+    assert file.read_text() == json.dumps(CURRENT_STATE, indent=4)
+
+
+def test_load_state(tmp_path: Path):
+    # Create a StateManager instance with a temporary file
+    file = tmp_path / "test_state.json"
+
+    # Write a temporary JSON file to read back
+    with open(file, "w") as f:
+        json.dump(LOAD_STATE, f, indent=4)
+
+    service = Service()
+    manager = StateManager(service=service, filename=str(file))
+    manager.load_state()
+    assert service.some_unit == u.Quantity(12, "A")
+
+
+def test_filename_warning(tmp_path: Path, caplog: LogCaptureFixture):
+    file = tmp_path / "test_state.json"
+
+    service = Service(filename=str(file))
+    StateManager(service=service, filename=str(file))
+    assert f"Overwriting filename {str(file)!r} with {str(file)!r}." in caplog.text
+
+
+def test_filename_error(caplog: LogCaptureFixture):
+    service = Service()
+    manager = StateManager(service=service)
+
+    manager.save_state()
+    assert (
+        "State manager was not initialised with a filename. Skipping 'save_state'..."
+        in caplog.text
+    )
+
+
+def test_readonly_attribute(tmp_path: Path, caplog: LogCaptureFixture):
+    # Create a StateManager instance with a temporary file
+    file = tmp_path / "test_state.json"
+
+    # Write a temporary JSON file to read back
+    with open(file, "w") as f:
+        json.dump(LOAD_STATE, f, indent=4)
+
+    service = Service()
+    manager = StateManager(service=service, filename=str(file))
+    manager.load_state()
+    assert (
+        "Attribute 'name' is read-only. Ignoring value from JSON file..." in caplog.text
+    )
+
+
+def test_changed_type(tmp_path: Path, caplog: LogCaptureFixture):
+    # Create a StateManager instance with a temporary file
+    file = tmp_path / "test_state.json"
+
+    # Write a temporary JSON file to read back
+    with open(file, "w") as f:
+        json.dump(LOAD_STATE, f, indent=4)
+
+    service = Service()
+    manager = StateManager(service=service, filename=str(file))
+    manager.load_state()
+    assert (
+        "Attribute type of 'some_float' changed from 'int' to "
+        "'float'. Ignoring value from JSON file..."
+    ) in caplog.text