Fix tesla_fleet media player volume step calculation (#175813)

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

homeassistant/components/tesla_fleet/media_player.py

@@ -76,14 +76,11 @@ class TeslaFleetMediaEntity(TeslaFleetVehicleEntity, MediaPlayerEntity):
         self._attr_state = STATES.get(
             self.get("vehicle_state_media_info_media_playback_status") or "Off",
         )
+        # volume_level is audio_volume / audio_volume_max, so one notch as a
+        # fraction of range is the per-notch increment divided by the max.
         self._attr_volume_step = (
-            1.0
-            / self._volume_max
-            / (
-                self.get("vehicle_state_media_info_audio_volume_increment")
-                or VOLUME_STEP
-            )
-        )
+            self.get("vehicle_state_media_info_audio_volume_increment") or VOLUME_STEP
+        ) / self._volume_max
 
         if volume := self.get("vehicle_state_media_info_audio_volume"):
             self._attr_volume_level = volume / self._volume_max

tests/components/tesla_fleet/test_media_player.py

@@ -2,6 +2,7 @@
 
 from unittest.mock import AsyncMock, patch
 
+import pytest
 from syrupy.assertion import SnapshotAssertion
 from tesla_fleet_api.exceptions import VehicleOffline
 
@@ -13,6 +14,7 @@ from homeassistant.components.media_player import (
     SERVICE_MEDIA_PLAY,
     SERVICE_MEDIA_PREVIOUS_TRACK,
     SERVICE_VOLUME_SET,
+    SERVICE_VOLUME_UP,
     MediaPlayerState,
 )
 from homeassistant.const import ATTR_ENTITY_ID, Platform
@@ -37,6 +39,35 @@ async def test_media_player(
     assert_entities(hass, normal_config_entry.entry_id, entity_registry, snapshot)
 
 
+async def test_media_player_volume_step(
+    hass: HomeAssistant,
+    normal_config_entry: MockConfigEntry,
+) -> None:
+    """Test volume_up raises the level by exactly one Tesla notch."""
+
+    await setup_platform(hass, normal_config_entry, [Platform.MEDIA_PLAYER])
+
+    entity_id = "media_player.test_media_player"
+
+    with patch(
+        "tesla_fleet_api.tesla.VehicleFleet.adjust_volume",
+        return_value=COMMAND_OK,
+    ):
+        await hass.services.async_call(
+            MEDIA_PLAYER_DOMAIN,
+            SERVICE_VOLUME_UP,
+            {ATTR_ENTITY_ID: entity_id},
+            blocking=True,
+        )
+
+    # One notch up from the vehicle_data fixture's audio_volume of 1.6667 in a
+    # 10.333333 range: (1.6667 + 0.333333) / 10.333333.
+    state = hass.states.get(entity_id)
+    assert state.attributes[ATTR_MEDIA_VOLUME_LEVEL] == pytest.approx(
+        0.1935516, abs=1e-4
+    )
+
+
 async def test_media_player_alt(
     hass: HomeAssistant,
     snapshot: SnapshotAssertion,