Add "significant change" base (#45555)

tests/helpers/test_significant_change.py

@@ -0,0 +1,50 @@
+"""Test significant change helper."""
+import pytest
+
+from homeassistant.components.sensor import DEVICE_CLASS_BATTERY
+from homeassistant.const import ATTR_DEVICE_CLASS, STATE_UNAVAILABLE, STATE_UNKNOWN
+from homeassistant.core import State
+from homeassistant.helpers import significant_change
+from homeassistant.setup import async_setup_component
+
+
+@pytest.fixture(name="checker")
+async def checker_fixture(hass):
+    """Checker fixture."""
+    checker = await significant_change.create_checker(hass, "test")
+
+    def async_check_significant_change(
+        _hass, old_state, _old_attrs, new_state, _new_attrs, **kwargs
+    ):
+        return abs(float(old_state) - float(new_state)) > 4
+
+    hass.data[significant_change.DATA_FUNCTIONS][
+        "test_domain"
+    ] = async_check_significant_change
+    return checker
+
+
+async def test_signicant_change(hass, checker):
+    """Test initialize helper works."""
+    assert await async_setup_component(hass, "sensor", {})
+
+    ent_id = "test_domain.test_entity"
+    attrs = {ATTR_DEVICE_CLASS: DEVICE_CLASS_BATTERY}
+
+    assert checker.async_is_significant_change(State(ent_id, "100", attrs))
+
+    # Same state is not significant.
+    assert not checker.async_is_significant_change(State(ent_id, "100", attrs))
+
+    # State under 5 difference is not significant. (per test mock)
+    assert not checker.async_is_significant_change(State(ent_id, "96", attrs))
+
+    # Make sure we always compare against last significant change
+    assert checker.async_is_significant_change(State(ent_id, "95", attrs))
+
+    # State turned unknown
+    assert checker.async_is_significant_change(State(ent_id, STATE_UNKNOWN, attrs))
+
+    # State turned unavailable
+    assert checker.async_is_significant_change(State(ent_id, "100", attrs))
+    assert checker.async_is_significant_change(State(ent_id, STATE_UNAVAILABLE, attrs))