Add duplicate lease exception (#22)

Author: tamirOK

aetcd/__init__.py

@@ -5,6 +5,7 @@
 from .exceptions import ClientError  # noqa: F401
 from .exceptions import ConnectionFailedError  # noqa: F401
 from .exceptions import ConnectionTimeoutError  # noqa: F401
+from .exceptions import DuplicateLeaseError  # noqa: F401
 from .exceptions import InternalError  # noqa: F401
 from .exceptions import InvalidArgumentError  # noqa: F401
 from .exceptions import PreconditionFailedError  # noqa: F401

aetcd/exceptions.py

@@ -29,6 +29,10 @@ class PreconditionFailedError(ClientError):
     """Raises on etcd server precondition errors."""
 
 
+class DuplicateLeaseError(ClientError):
+    """Raised on attempt to create lease with already existing id."""
+
+
 class RevisionCompactedError(ClientError):
     """Raises when requested and previous revisions were already compacted."""
 
@@ -68,9 +72,13 @@ def _handle_exception(error: Exception):
     # Query RPC error mapping and raise one of the matched client errors
     if isinstance(error, rpc.AioRpcError):
         e = _EXCEPTIONS_BY_CODE.get(error.code())
+        error_details = error.details()
+
         if e is not None:
-            raise e(error.details()) from error
-        raise ClientError(error.details()) from error
+            if e is PreconditionFailedError and 'lease already exists' in error_details:
+                raise DuplicateLeaseError
+            raise e(error_details) from error
+        raise ClientError(error_details) from error
 
     # Fallback to wrap original error with the client error
     raise ClientError(error)

tests/integration/test_lease.py

@@ -2,6 +2,8 @@
 
 import pytest
 
+import aetcd.exceptions
+
 
 @pytest.mark.asyncio
 async def test_lease_grant(etcd):
@@ -44,3 +46,11 @@ async def test_lease_expire(etcd):
     await asyncio.sleep((await lease.granted_ttl()) + 1)
     result = await etcd.get(key)
     assert result is None
+
+
+@pytest.mark.asyncio
+async def test_lease_create_with_already_existing_id(etcd):
+    await etcd.lease(10, lease_id=123)
+
+    with pytest.raises(aetcd.exceptions.DuplicateLeaseError):
+        await etcd.lease(15, lease_id=123)

tests/test_exceptions.py

@@ -67,3 +67,23 @@ def test__handle_exception_with_unknown_errors(rpc_error):
 
     with pytest.raises(aetcd.exceptions.ClientError, match='unknown error'):
         aetcd.exceptions._handle_exception(error)
+
+
+def test__handle_exception_with_duplicate_lease_error(rpc_error):
+    error = rpc_error(
+        code=aetcd.rpc.StatusCode.FAILED_PRECONDITION,
+        details='etcdserver: lease already exists',
+    )
+
+    with pytest.raises(aetcd.exceptions.DuplicateLeaseError):
+        aetcd.exceptions._handle_exception(error)
+
+
+def test__handle_exception_with_duplicate_lease_error_and_internal_rpc_error(rpc_error):
+    error = rpc_error(
+        code=aetcd.rpc.StatusCode.INTERNAL,
+        details='etcdserver: lease already exists',
+    )
+
+    with pytest.raises(aetcd.exceptions.InternalError):
+        aetcd.exceptions._handle_exception(error)