Add method to fetch capability schema (#147)

src/pysmartthings/smartthings.py

@@ -11,6 +11,7 @@
 from aiohttp.hdrs import METH_DELETE, METH_GET, METH_POST, METH_PUT
 from yarl import URL
 
+from . import SmartThingsAuthenticationFailedError
 from .const import API_BASE
 from .exceptions import SmartThingsCommandError, SmartThingsConnectionError
 from .models import (
@@ -97,6 +98,10 @@ async def _request(
 
         text = await response.text()
 
+        if response.status == 401:
+            msg = "Authentication failed with SmartThings"
+            raise SmartThingsAuthenticationFailedError(msg)
+
         if response.status == 422:
             raise SmartThingsCommandError(ErrorResponse.from_json(text))
 
@@ -195,6 +200,10 @@ async def get_device_status(
         resp = await self._get(f"devices/{device_id}/status")
         return DeviceStatus.from_json(resp).components
 
+    async def get_capability(self, capability: Capability | str) -> str:
+        """Retrieve the capability schema."""
+        return await self._get(f"capabilities/{capability}/1")
+
     async def execute_device_command(
         self,
         device_id: str,