Fix holiday HA language not supported (#106554)

homeassistant/components/holiday/config_flow.py

@@ -3,7 +3,7 @@ from __future__ import annotations
 
 from typing import Any
 
-from babel import Locale
+from babel import Locale, UnknownLocaleError
 from holidays import list_supported_countries
 import voluptuous as vol
 
@@ -46,7 +46,12 @@ class HolidayConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
 
             self._async_abort_entries_match({CONF_COUNTRY: user_input[CONF_COUNTRY]})
 
-            locale = Locale(self.hass.config.language)
+            try:
+                locale = Locale(self.hass.config.language)
+            except UnknownLocaleError:
+                # Default to (US) English if language not recognized by babel
+                # Mainly an issue with English flavors such as "en-GB"
+                locale = Locale("en")
             title = locale.territories[selected_country]
             return self.async_create_entry(title=title, data=user_input)
 
@@ -81,7 +86,12 @@ class HolidayConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
                 }
             )
 
-            locale = Locale(self.hass.config.language)
+            try:
+                locale = Locale(self.hass.config.language)
+            except UnknownLocaleError:
+                # Default to (US) English if language not recognized by babel
+                # Mainly an issue with English flavors such as "en-GB"
+                locale = Locale("en")
             province_str = f", {province}" if province else ""
             name = f"{locale.territories[country]}{province_str}"
 

tests/components/holiday/test_config_flow.py

@@ -126,3 +126,22 @@ async def test_single_combination_country_province(hass: HomeAssistant) -> None:
     )
     assert result_de_step2["type"] == FlowResultType.ABORT
     assert result_de_step2["reason"] == "already_configured"
+
+
+async def test_form_babel_unresolved_language(hass: HomeAssistant) -> None:
+    """Test the config flow if using not babel supported language."""
+    hass.config.language = "en-GB"
+
+    result = await hass.config_entries.flow.async_init(
+        DOMAIN, context={"source": config_entries.SOURCE_USER}
+    )
+
+    result2 = await hass.config_entries.flow.async_configure(
+        result["flow_id"],
+        {
+            CONF_COUNTRY: "SE",
+        },
+    )
+    await hass.async_block_till_done()
+
+    assert result2["title"] == "Sweden"