Area registry (#20435)

* First draft of area registry

* Refactor based on input

* Add tests for areas
Add tests for updating device

* Updating a device shouldn't require area

* Fix Martins comment

* Require admin

* Save after deleting

* Rename read to list_areas
Fix device entry_dict
Remove area id from device when deleting area

* Fix tests

tests/helpers/test_area_registry.py

@@ -0,0 +1,127 @@
+"""Tests for the Area Registry."""
+import pytest
+
+from homeassistant.helpers import area_registry
+from tests.common import mock_area_registry, flush_store
+
+
+@pytest.fixture
+def registry(hass):
+    """Return an empty, loaded, registry."""
+    return mock_area_registry(hass)
+
+
+async def test_list_areas(registry):
+    """Make sure that we can read areas."""
+    registry.async_create('mock')
+
+    areas = registry.async_list_areas()
+
+    assert len(areas) == len(registry.areas)
+
+
+async def test_create_area(registry):
+    """Make sure that we can create an area."""
+    area = registry.async_create('mock')
+
+    assert area.name == 'mock'
+    assert len(registry.areas) == 1
+
+
+async def test_create_area_with_name_already_in_use(registry):
+    """Make sure that we can't create an area with a name already in use."""
+    area1 = registry.async_create('mock')
+
+    with pytest.raises(ValueError) as e_info:
+        area2 = registry.async_create('mock')
+        assert area1 != area2
+        assert e_info == "Name is already in use"
+
+    assert len(registry.areas) == 1
+
+
+async def test_delete_area(registry):
+    """Make sure that we can delete an area."""
+    area = registry.async_create('mock')
+
+    await registry.async_delete(area.id)
+
+    assert not registry.areas
+
+
+async def test_delete_non_existing_area(registry):
+    """Make sure that we can't delete an area that doesn't exist."""
+    registry.async_create('mock')
+
+    with pytest.raises(KeyError):
+        await registry.async_delete('')
+
+    assert len(registry.areas) == 1
+
+
+async def test_update_area(registry):
+    """Make sure that we can read areas."""
+    area = registry.async_create('mock')
+
+    updated_area = registry.async_update(area.id, name='mock1')
+
+    assert updated_area != area
+    assert updated_area.name == 'mock1'
+    assert len(registry.areas) == 1
+
+
+async def test_update_area_with_same_name(registry):
+    """Make sure that we can reapply the same name to the area."""
+    area = registry.async_create('mock')
+
+    updated_area = registry.async_update(area.id, name='mock')
+
+    assert updated_area == area
+    assert len(registry.areas) == 1
+
+
+async def test_update_area_with_name_already_in_use(registry):
+    """Make sure that we can't update an area with a name already in use."""
+    area1 = registry.async_create('mock1')
+    area2 = registry.async_create('mock2')
+
+    with pytest.raises(ValueError) as e_info:
+        registry.async_update(area1.id, name='mock2')
+        assert e_info == "Name is already in use"
+
+    assert area1.name == 'mock1'
+    assert area2.name == 'mock2'
+    assert len(registry.areas) == 2
+
+
+async def test_load_area(hass, registry):
+    """Make sure that we can load/save data correctly."""
+    registry.async_create('mock1')
+    registry.async_create('mock2')
+
+    assert len(registry.areas) == 2
+
+    registry2 = area_registry.AreaRegistry(hass)
+    await flush_store(registry._store)
+    await registry2.async_load()
+
+    assert list(registry.areas) == list(registry2.areas)
+
+
+async def test_loading_area_from_storage(hass, hass_storage):
+    """Test loading stored areas on start."""
+    hass_storage[area_registry.STORAGE_KEY] = {
+        'version': area_registry.STORAGE_VERSION,
+        'data': {
+            'areas': [
+                {
+                    'id': '12345A',
+                    'name': 'mock'
+                }
+            ]
+        }
+    }
+
+    registry = await area_registry.async_get_registry(hass)
+
+    assert len(registry.areas) == 1