BUG: Raise ClientAuthenticationError in default get credential (#659)

Device Login was skipped because exception not raised

hi-ml-azure/src/health_azure/utils.py

@@ -2164,17 +2164,13 @@ def _get_legitimate_device_code_credential() -> Optional[TokenCredential]:
 
 def _get_legitimate_default_credential() -> Optional[TokenCredential]:
     """
-    Create a DefaultAzure credential for interacting with Azure resources. If the credential can't be
-    validated, return None.
+    Create a DefaultAzure credential for interacting with Azure resources and validates it.
 
     :return: A valid Azure credential.
     """
     cred = DefaultAzureCredential(timeout=60)
-    try:
-        _validate_credential(cred)
-        return cred
-    except ClientAuthenticationError:
-        return None
+    _validate_credential(cred)
+    return cred
 
 
 def _get_legitimate_interactive_browser_credential() -> Optional[TokenCredential]:

hi-ml-azure/testazure/testazure/test_azure_util.py

@@ -2477,8 +2477,9 @@ def test_get_legitimate_default_credential() -> None:
         return DefaultAzureCredential(timeout=1)
 
     with patch("health_azure.utils.DefaultAzureCredential", new=_mock_credential_fast_timeout):
-        cred = util._get_legitimate_default_credential()
-        assert cred is None
+        exception_message = r"DefaultAzureCredential failed to retrieve a token from the included credentials."
+        with pytest.raises(ClientAuthenticationError, match=exception_message):
+            cred = util._get_legitimate_default_credential()
 
     with patch("health_azure.utils._validate_credential"):
         cred = util._get_legitimate_default_credential()