Add fallback equality relationship based on uuid

aiida/orm/nodes/node.py

@@ -12,6 +12,7 @@
 import importlib
 import warnings
 import traceback
+from uuid import UUID
 from typing import List, Optional
 
 from aiida.common import exceptions
@@ -180,6 +181,16 @@ def __init__(self, backend=None, user=None, computer=None, **kwargs):
         )
         super().__init__(backend_entity)
 
+    def __eq__(self, other):
+        """Fallback equality comparison by uuid (can be overwritten by specific types)"""
+        if isinstance(other, Node) and self.uuid == other.uuid:
+            return True
+        return super().__eq__(other)
+
+    def __hash__(self):
+        """Python-Hash: Implementation that is compatible with __eq__"""
+        return UUID(self.uuid).int
+
     def __repr__(self):
         return f'<{self.__class__.__name__}: {str(self)}>'
 

tests/engine/test_ports.py

@@ -92,7 +92,7 @@ def test_serialize_type_check(self):
         port_namespace.create_port_namespace(nested_namespace)
 
         with self.assertRaisesRegex(TypeError, f'.*{base_namespace}.*{nested_namespace}.*'):
-            port_namespace.serialize({'some': {'nested': {'namespace': {Dict()}}}})
+            port_namespace.serialize({'some': {'nested': {'namespace': Dict()}}})
 
     def test_lambda_default(self):
         """Test that an input port can specify a lambda as a default."""

tests/orm/node/test_node.py

@@ -923,3 +923,21 @@ def test_open_wrapper():
     iter(node.open(filename))
     node.open(filename).__next__()
     node.open(filename).__iter__()
+
+
+@pytest.mark.usefixtures('clear_database_before_test')
+def test_uuid_equality_fallback():
+    """Tests the fallback mechanism of checking equality by comparing uuids and hash."""
+    node_0 = Data().store()
+
+    nodepk = Data().store().pk
+    node_a = load_node(pk=nodepk)
+    node_b = load_node(pk=nodepk)
+
+    assert node_a == node_b
+    assert node_a != node_0
+    assert node_b != node_0
+
+    assert hash(node_a) == hash(node_b)
+    assert hash(node_a) != hash(node_0)
+    assert hash(node_b) != hash(node_0)