Add datetime platform (#81943)

Co-authored-by: Franck Nijhof <frenck@frenck.nl>
Co-authored-by: Franck Nijhof <git@frenck.dev>

tests/components/demo/test_datetime.py

@@ -0,0 +1,35 @@
+"""The tests for the demo datetime component."""
+import pytest
+
+from homeassistant.components.datetime import ATTR_DATETIME, DOMAIN, SERVICE_SET_VALUE
+from homeassistant.const import ATTR_ENTITY_ID
+from homeassistant.core import HomeAssistant
+from homeassistant.setup import async_setup_component
+
+ENTITY_DATETIME = "datetime.date_and_time"
+
+
+@pytest.fixture(autouse=True)
+async def setup_demo_datetime(hass: HomeAssistant) -> None:
+    """Initialize setup demo datetime."""
+    assert await async_setup_component(hass, DOMAIN, {"datetime": {"platform": "demo"}})
+    await hass.async_block_till_done()
+
+
+def test_setup_params(hass: HomeAssistant) -> None:
+    """Test the initial parameters."""
+    state = hass.states.get(ENTITY_DATETIME)
+    assert state.state == "2020-01-01T12:00:00+00:00"
+
+
+async def test_set_datetime(hass: HomeAssistant) -> None:
+    """Test set datetime service."""
+    hass.config.set_time_zone("UTC")
+    await hass.services.async_call(
+        DOMAIN,
+        SERVICE_SET_VALUE,
+        {ATTR_ENTITY_ID: ENTITY_DATETIME, ATTR_DATETIME: "2021-02-03 01:02:03"},
+        blocking=True,
+    )
+    state = hass.states.get(ENTITY_DATETIME)
+    assert state.state == "2021-02-03T01:02:03+00:00"