Implemented a first and basic version of a Rete rule engine

tests/non_reg/test_sheerka_non_reg.py

@@ -1230,7 +1230,7 @@ as:
         assert res[0].body == 21
 
     def test_i_can_define_rules_priorities(self):
-        sheerka, context, r1, r2 = self.init_test().with_rules(("True", "True"), ("False", "False")).unpack()
+        sheerka, context, r1, r2 = self.init_test().with_format_rules(("True", "True"), ("False", "False")).unpack()
         sheerka.evaluate_user_input("def concept rule x > rule y where isinstance(x, int) and isinstance(y, int) as set_is_greater_than(__PRECEDENCE, r:|x:, r:|y:, 'Rule')")
 
         res = sheerka.evaluate_user_input(f"eval rule {r1.id} > rule {r2.id}")

tests/non_reg/test_sheerka_non_reg_out.py

@@ -51,6 +51,23 @@ post      : None
 ret       : None
 vars      : []
 props     : {}
+"""
+
+    def test_i_can_describe_a_rule(self, capsys):
+        sheerka = self.get_sheerka()
+
+        sheerka.enable_process_return_values = True
+        sheerka.evaluate_user_input("desc(r:|1:)")
+        captured = capsys.readouterr()
+
+        assert captured.out == """id       : 1
+name     : Print return values
+type     : print
+predicate: __rets
+action   : list(__rets)
+priority : 4
+compiled : True
+enabled  : True
 """
 
     def test_i_can_display_multiple_success(self, capsys):

tests/non_reg/test_sheerka_non_reg_rules.py

@@ -0,0 +1,25 @@
+from core.builtin_concepts_ids import BuiltinConcepts
+from evaluators.PythonEvaluator import PythonEvalError
+from tests.TestUsingMemoryBasedSheerka import TestUsingMemoryBasedSheerka
+
+
+class TestSheerkaNonRegDisplay(TestUsingMemoryBasedSheerka):
+
+    def test_i_can_apply_simple_rule(self):
+        init = [
+            "def concept one as 1",
+            "when __ret.status then test_error()",
+        ]
+
+        sheerka = self.init_scenario(init)
+        sheerka.enable_process_rules = True
+        res = sheerka.evaluate_user_input("one")
+
+        assert len(res) == 1
+        ret = res[0]
+
+        assert not ret.status
+        assert sheerka.isinstance(ret.body, BuiltinConcepts.ERROR)
+        assert isinstance(ret.body.body, PythonEvalError)
+        assert isinstance(ret.body.body.error, Exception)
+        assert ret.body.body.error.args == ("I can raise an error",)