Add more dunder methods

Signed-off-by: Paul Van Eck <[email protected]>

sdk/core/azure-core/azure/core/credentials.py

@@ -3,7 +3,7 @@
 # Licensed under the MIT License. See LICENSE.txt in the project root for
 # license information.
 # -------------------------------------------------------------------------
-from dataclasses import dataclass
+from dataclasses import dataclass, fields
 from typing import Any, NamedTuple, Optional
 from typing_extensions import Protocol, runtime_checkable
 
@@ -30,6 +30,28 @@ def __iter__(self) -> Any:
         yield self.token
         yield self.expires_on
 
+    def __getitem__(self, index: Any) -> Any:
+        """Access the value at the given index.
+
+        :param Any index: The index to access.
+        :return: The value at the given index.
+        :rtype: Any
+        """
+        token_fields = fields(self)
+        field = token_fields[index]
+        if isinstance(field, tuple):
+            # Handle slices
+            return tuple(getattr(self, field[i].name) for i in range(len(field)))
+        return getattr(self, field.name)
+
+    def __len__(self) -> int:
+        """Return the number of fields in the AccessToken.
+
+        :return: The number of fields in the AccessToken.
+        :rtype: int
+        """
+        return len(fields(self))
+
 
 @runtime_checkable
 class TokenCredential(Protocol):

sdk/core/azure-core/tests/test_authentication.py

@@ -642,8 +642,27 @@ def verify_authorization_header(request):
 
 def test_access_token_unpack_backwards_compat():
     """Test that AccessToken can be unpacked as a two-value tuple for backwards compatibility."""
-    _ = AccessToken("token", 42)
+    token = AccessToken("token", 42)
+    assert token.token == "token"
+    assert token.expires_on == 42
+    assert token.refresh_on is None
+
     _, _ = AccessToken("token", 42)
     _, _ = AccessToken(token="token", expires_on=42)
     _, _ = AccessToken("token", 42, 42)
     _, _ = AccessToken(token="token", expires_on=42, refresh_on=42)
+
+
+def test_access_token_subscriptable():
+    """Test that AccessToken can be indexed by position. This is verify backwards-compatibility."""
+    token = AccessToken("token", 42)
+    assert token[0] == "token"
+    assert token[1] == 42
+    assert token[2] is None
+    token = AccessToken("token", 42, 100)
+    assert token[:2] == ("token", 42)
+    assert token[:3] == ("token", 42, 100)
+    assert token[:-1] == ("token", 42)
+    assert len(token) == 3
+    with pytest.raises(IndexError):
+        _ = token[3]