From bb844840965b8a866f324595f29486590db10003 Mon Sep 17 00:00:00 2001
From: Paulus Schoutsen <balloob@gmail.com>
Date: Sun, 3 Jul 2022 22:03:13 -0700
Subject: [PATCH] Guard invalid data sensor significant change (#74369)

---
 .../components/sensor/significant_change.py    | 18 ++++++++++++++----
 .../sensor/test_significant_change.py          |  2 ++
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/homeassistant/components/sensor/significant_change.py b/homeassistant/components/sensor/significant_change.py
index 31b4f00c37f..6ff23b43508 100644
--- a/homeassistant/components/sensor/significant_change.py
+++ b/homeassistant/components/sensor/significant_change.py
@@ -63,13 +63,23 @@ def async_check_significant_change(
         absolute_change = 1.0
         percentage_change = 2.0
 
+    try:
+        # New state is invalid, don't report it
+        new_state_f = float(new_state)
+    except ValueError:
+        return False
+
+    try:
+        # Old state was invalid, we should report again
+        old_state_f = float(old_state)
+    except ValueError:
+        return True
+
     if absolute_change is not None and percentage_change is not None:
         return _absolute_and_relative_change(
-            float(old_state), float(new_state), absolute_change, percentage_change
+            old_state_f, new_state_f, absolute_change, percentage_change
         )
     if absolute_change is not None:
-        return check_absolute_change(
-            float(old_state), float(new_state), absolute_change
-        )
+        return check_absolute_change(old_state_f, new_state_f, absolute_change)
 
     return None
diff --git a/tests/components/sensor/test_significant_change.py b/tests/components/sensor/test_significant_change.py
index 051a92f3b07..bfa01d6eb08 100644
--- a/tests/components/sensor/test_significant_change.py
+++ b/tests/components/sensor/test_significant_change.py
@@ -52,6 +52,8 @@ TEMP_FREEDOM_ATTRS = {
         ("12.1", "12.2", TEMP_CELSIUS_ATTRS, False),
         ("70", "71", TEMP_FREEDOM_ATTRS, True),
         ("70", "70.5", TEMP_FREEDOM_ATTRS, False),
+        ("fail", "70", TEMP_FREEDOM_ATTRS, True),
+        ("70", "fail", TEMP_FREEDOM_ATTRS, False),
     ],
 )
 async def test_significant_change_temperature(old_state, new_state, attrs, result):