[sensor] Fix delta filter percentage mode regression (#14302)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

esphome/components/sensor/__init__.py

@@ -603,7 +603,7 @@ DELTA_SCHEMA = cv.Any(
 def _get_delta(value):
     if isinstance(value, str):
         assert value.endswith("%")
-        return 0.0, float(value[:-1])
+        return 0.0, float(value[:-1]) / 100.0
     return value, 0.0
 
 

tests/integration/fixtures/sensor_filters_delta.yaml

@@ -28,6 +28,11 @@ sensor:
     id: source_sensor_4
     accuracy_decimals: 1
 
+  - platform: template
+    name: "Source Sensor 5"
+    id: source_sensor_5
+    accuracy_decimals: 1
+
   - platform: copy
     source_id: source_sensor_1
     name: "Filter Min"
@@ -69,6 +74,13 @@ sensor:
     filters:
       - delta: 0
 
+  - platform: copy
+    source_id: source_sensor_5
+    name: "Filter Percentage"
+    id: filter_percentage
+    filters:
+      - delta: 50%
+
 script:
   - id: test_filter_min
     then:
@@ -154,6 +166,28 @@ script:
           id: source_sensor_4
           state: 2.0
 
+  - id: test_filter_percentage
+    then:
+      - sensor.template.publish:
+          id: source_sensor_5
+          state: 100.0
+      - delay: 20ms
+      - sensor.template.publish:
+          id: source_sensor_5
+          state: 120.0  # Filtered out (delta=20, need >50)
+      - delay: 20ms
+      - sensor.template.publish:
+          id: source_sensor_5
+          state: 160.0  # Passes (delta=60 > 50% of 100=50)
+      - delay: 20ms
+      - sensor.template.publish:
+          id: source_sensor_5
+          state: 200.0  # Filtered out (delta=40, need >50% of 160=80)
+      - delay: 20ms
+      - sensor.template.publish:
+          id: source_sensor_5
+          state: 250.0  # Passes (delta=90 > 80)
+
 button:
   - platform: template
     name: "Test Filter Min"
@@ -178,3 +212,9 @@ button:
     id: btn_filter_zero_delta
     on_press:
       - script.execute: test_filter_zero_delta
+
+  - platform: template
+    name: "Test Filter Percentage"
+    id: btn_filter_percentage
+    on_press:
+      - script.execute: test_filter_percentage

tests/integration/test_sensor_filters_delta.py

@@ -24,12 +24,14 @@ async def test_sensor_filters_delta(
         "filter_max": [],
         "filter_baseline_max": [],
         "filter_zero_delta": [],
+        "filter_percentage": [],
     }
 
     filter_min_done = loop.create_future()
     filter_max_done = loop.create_future()
     filter_baseline_max_done = loop.create_future()
     filter_zero_delta_done = loop.create_future()
+    filter_percentage_done = loop.create_future()
 
     def on_state(state: EntityState) -> None:
         if not isinstance(state, SensorState) or state.missing_state:
@@ -66,6 +68,12 @@ async def test_sensor_filters_delta(
             and not filter_zero_delta_done.done()
         ):
             filter_zero_delta_done.set_result(True)
+        elif (
+            sensor_name == "filter_percentage"
+            and len(sensor_values[sensor_name]) == 3
+            and not filter_percentage_done.done()
+        ):
+            filter_percentage_done.set_result(True)
 
     async with (
         run_compiled(yaml_config),
@@ -80,6 +88,7 @@ async def test_sensor_filters_delta(
                 "filter_max": "Filter Max",
                 "filter_baseline_max": "Filter Baseline Max",
                 "filter_zero_delta": "Filter Zero Delta",
+                "filter_percentage": "Filter Percentage",
             },
         )
 
@@ -98,13 +107,14 @@ async def test_sensor_filters_delta(
             "Test Filter Max": "filter_max",
             "Test Filter Baseline Max": "filter_baseline_max",
             "Test Filter Zero Delta": "filter_zero_delta",
+            "Test Filter Percentage": "filter_percentage",
         }
         buttons = {}
         for entity in entities:
             if isinstance(entity, ButtonInfo) and entity.name in button_name_map:
                 buttons[button_name_map[entity.name]] = entity.key
 
-        assert len(buttons) == 4, f"Expected 3 buttons, found {len(buttons)}"
+        assert len(buttons) == 5, f"Expected 5 buttons, found {len(buttons)}"
 
         # Test 1: Min
         sensor_values["filter_min"].clear()
@@ -161,3 +171,18 @@ async def test_sensor_filters_delta(
         assert sensor_values["filter_zero_delta"] == pytest.approx(expected), (
             f"Test 4 failed: expected {expected}, got {sensor_values['filter_zero_delta']}"
         )
+
+        # Test 5: Percentage (delta: 50%)
+        sensor_values["filter_percentage"].clear()
+        client.button_command(buttons["filter_percentage"])
+        try:
+            await asyncio.wait_for(filter_percentage_done, timeout=2.0)
+        except TimeoutError:
+            pytest.fail(
+                f"Test 5 timed out. Values: {sensor_values['filter_percentage']}"
+            )
+
+        expected = [100.0, 160.0, 250.0]
+        assert sensor_values["filter_percentage"] == pytest.approx(expected), (
+            f"Test 5 failed: expected {expected}, got {sensor_values['filter_percentage']}"
+        )