Implement __deepcopy__ on ImmutableDict

Closes #13408
(grafted from cdb34d214369c682c1d8f21fcb8c143371557cb9)

--HG--
branch : 7.0

trytond/trytond/tests/test_tools.py

@@ -6,6 +6,7 @@ import datetime as dt
 import doctest
 import sys
 import unittest
+from copy import deepcopy
 from io import BytesIO
 
 import sql
@@ -547,6 +548,17 @@ class ImmutableDictTestCase(unittest.TestCase):
         with self.assertRaises(TypeError):
             d.update({'foo': 'bar'})
 
+    def test_deepcopy(self):
+        "deepcopying should be possible"
+        original = ImmutableDict(foo={'a': 1}, bar=2, baz=1.3)
+        copy = deepcopy(original)
+
+        self.assertEqual(original, copy)
+        self.assertIsNot(original, copy)
+
+        self.assertEqual(original['foo'], copy['foo'])
+        self.assertIsNot(original['foo'], copy['foo'])
+
 
 class DomainInversionTestCase(unittest.TestCase):
     "Test domain_inversion"

trytond/trytond/tools/immutabledict.py

@@ -1,5 +1,7 @@
 # This file is part of Tryton.  The COPYRIGHT file at the toplevel of this
 # repository contains the full copyright notices and license terms.
+from copy import deepcopy
+
 
 class ImmutableDict(dict):
 
@@ -8,6 +10,10 @@ class ImmutableDict(dict):
     def _not_allowed(cls, *args, **kwargs):
         raise TypeError("Operation not allowed on ImmutableDict")
 
+    def __deepcopy__(self, memo):
+        return ImmutableDict(
+            (k, deepcopy(v, memo=memo)) for k, v in self.items())
+
     __setitem__ = _not_allowed
     __delitem__ = _not_allowed
     __ior__ = _not_allowed