Concepts bodies are now evaluated on demand

tests/evaluators/test_AddConceptInSetEvaluator.py

@@ -66,6 +66,31 @@ class TestAddConceptInSetEvaluator(TestUsingMemoryBasedSheerka):
         foo_from_sheerka = context.sheerka.get("foo")
         assert foo_from_sheerka.get_prop(BuiltinConcepts.ISA) == [bar]
 
+    def test_i_can_add_bnf_concept_to_a_set_of_concept(self):
+        """
+        This test is the reason why I have started the whole eval on demand stuff
+        Sheerka tries to evaluate the body but it can (as a and b are not defined)
+        So 'foo' cannot be put is set
+        :return:
+        """
+        sheerka, context, foo, bar = self.init_concepts(
+            Concept("foo", definition="a plus b", body="a + b").def_prop("a").def_prop("b"),
+            "bar",
+            create_new=True)
+
+        ret_val = get_ret_val("foo", "bar")
+        res = AddConceptInSetEvaluator().eval(context, ret_val)
+        foo = sheerka.new("foo")  # reload it
+
+        assert res.status
+        assert context.sheerka.isinstance(res.value, BuiltinConcepts.SUCCESS)
+        assert context.sheerka.isaset(context, bar)
+        assert context.sheerka.isinset(foo, bar)
+        assert context.sheerka.isa(foo, bar)
+
+        foo_from_sheerka = context.sheerka.get("foo")
+        assert foo_from_sheerka.get_prop(BuiltinConcepts.ISA) == [bar]
+
     def test_i_can_add_concept_with_a_body_to_a_set_of_concept(self):
         context = self.get_context()
         foo = Concept("foo", body="1")