Apply ConfigEntryNotReady improvements to PlatformNotReady (#48665)

* Apply ConfigEntryNotReady improvements to PlatformNotReady

- Limit log spam #47201
- Log exception reason #48449
- Prevent startup blockage #48660

* coverage

tests/helpers/test_entity_platform.py

@@ -6,8 +6,8 @@ from unittest.mock import Mock, patch
 
 import pytest
 
-from homeassistant.const import PERCENTAGE
-from homeassistant.core import callback
+from homeassistant.const import EVENT_HOMEASSISTANT_STARTED, PERCENTAGE
+from homeassistant.core import CoreState, callback
 from homeassistant.exceptions import HomeAssistantError, PlatformNotReady
 from homeassistant.helpers import (
     device_registry as dr,
@@ -592,6 +592,52 @@ async def test_setup_entry_platform_not_ready(hass, caplog):
     assert len(mock_call_later.mock_calls) == 1
 
 
+async def test_setup_entry_platform_not_ready_with_message(hass, caplog):
+    """Test when an entry is not ready yet that includes a message."""
+    async_setup_entry = Mock(side_effect=PlatformNotReady("lp0 on fire"))
+    platform = MockPlatform(async_setup_entry=async_setup_entry)
+    config_entry = MockConfigEntry()
+    ent_platform = MockEntityPlatform(
+        hass, platform_name=config_entry.domain, platform=platform
+    )
+
+    with patch.object(entity_platform, "async_call_later") as mock_call_later:
+        assert not await ent_platform.async_setup_entry(config_entry)
+
+    full_name = f"{ent_platform.domain}.{config_entry.domain}"
+    assert full_name not in hass.config.components
+    assert len(async_setup_entry.mock_calls) == 1
+
+    assert "Platform test not ready yet" in caplog.text
+    assert "lp0 on fire" in caplog.text
+    assert len(mock_call_later.mock_calls) == 1
+
+
+async def test_setup_entry_platform_not_ready_from_exception(hass, caplog):
+    """Test when an entry is not ready yet that includes the causing exception string."""
+    original_exception = HomeAssistantError("The device dropped the connection")
+    platform_exception = PlatformNotReady()
+    platform_exception.__cause__ = original_exception
+
+    async_setup_entry = Mock(side_effect=platform_exception)
+    platform = MockPlatform(async_setup_entry=async_setup_entry)
+    config_entry = MockConfigEntry()
+    ent_platform = MockEntityPlatform(
+        hass, platform_name=config_entry.domain, platform=platform
+    )
+
+    with patch.object(entity_platform, "async_call_later") as mock_call_later:
+        assert not await ent_platform.async_setup_entry(config_entry)
+
+    full_name = f"{ent_platform.domain}.{config_entry.domain}"
+    assert full_name not in hass.config.components
+    assert len(async_setup_entry.mock_calls) == 1
+
+    assert "Platform test not ready yet" in caplog.text
+    assert "The device dropped the connection" in caplog.text
+    assert len(mock_call_later.mock_calls) == 1
+
+
 async def test_reset_cancels_retry_setup(hass):
     """Test that resetting a platform will cancel scheduled a setup retry."""
     async_setup_entry = Mock(side_effect=PlatformNotReady)
@@ -614,6 +660,31 @@ async def test_reset_cancels_retry_setup(hass):
     assert ent_platform._async_cancel_retry_setup is None
 
 
+async def test_reset_cancels_retry_setup_when_not_started(hass):
+    """Test that resetting a platform will cancel scheduled a setup retry when not yet started."""
+    hass.state = CoreState.starting
+    async_setup_entry = Mock(side_effect=PlatformNotReady)
+    initial_listeners = hass.bus.async_listeners()[EVENT_HOMEASSISTANT_STARTED]
+
+    platform = MockPlatform(async_setup_entry=async_setup_entry)
+    config_entry = MockConfigEntry()
+    ent_platform = MockEntityPlatform(
+        hass, platform_name=config_entry.domain, platform=platform
+    )
+
+    assert not await ent_platform.async_setup_entry(config_entry)
+    await hass.async_block_till_done()
+    assert (
+        hass.bus.async_listeners()[EVENT_HOMEASSISTANT_STARTED] == initial_listeners + 1
+    )
+    assert ent_platform._async_cancel_retry_setup is not None
+
+    await ent_platform.async_reset()
+    await hass.async_block_till_done()
+    assert hass.bus.async_listeners()[EVENT_HOMEASSISTANT_STARTED] == initial_listeners
+    assert ent_platform._async_cancel_retry_setup is None
+
+
 async def test_not_fails_with_adding_empty_entities_(hass):
     """Test for not fails on empty entities list."""
     component = EntityComponent(_LOGGER, DOMAIN, hass)