Allow fetching media player covers via websocket connection (#14233)

Lint

tests/components/media_player/test_init.py

@@ -0,0 +1,37 @@
+"""Test the base functions of the media player."""
+import base64
+from unittest.mock import patch
+
+from homeassistant.setup import async_setup_component
+from homeassistant.components import websocket_api
+
+from tests.common import mock_coro
+
+
+async def test_get_panels(hass, hass_ws_client):
+    """Test get_panels command."""
+    await async_setup_component(hass, 'media_player', {
+        'media_player': {
+            'platform': 'demo'
+        }
+    })
+
+    client = await hass_ws_client(hass)
+
+    with patch('homeassistant.components.media_player.MediaPlayerDevice.'
+               'async_get_media_image', return_value=mock_coro(
+                   (b'image', 'image/jpeg'))):
+        await client.send_json({
+            'id': 5,
+            'type': 'media_player_thumbnail',
+            'entity_id': 'media_player.bedroom',
+        })
+
+        msg = await client.receive_json()
+
+    assert msg['id'] == 5
+    assert msg['type'] == websocket_api.TYPE_RESULT
+    assert msg['success']
+    assert msg['result']['content_type'] == 'image/jpeg'
+    assert msg['result']['content'] == \
+        base64.b64encode(b'image').decode('utf-8')