Implemented a first and basic version of a Rete rule engine

tests/sheerkarete/test_common.py

@@ -0,0 +1,31 @@
+from sheerkarete.common import ReteToken, WME, V
+from sheerkarete.conditions import Condition, NegatedConjunctiveConditions
+
+
+def test_token():
+    tdummy = ReteToken(None, None)
+    t0 = ReteToken(tdummy, WME('B1', 'on', 'B2'))
+
+    assert tdummy.parent is None
+    assert t0.parent == tdummy
+
+    assert tdummy.children == [t0]
+    assert t0.children == []
+
+
+def test_condition_vars():
+    c0 = Condition(V('x'), 'is', V('y'))
+    assert c0.vars == [('identifier', V("x")), ('value', V("y"))]
+
+
+def test_condition_contain():
+    c0 = Condition(V('a'), V('b'), V('c'))
+    assert c0.contain(V('a'))
+    assert not c0.contain(V('d'))
+
+
+def test_ncc():
+    c0 = Condition(V('a'), V('b'), V('c'))
+    c1 = NegatedConjunctiveConditions(Condition(V('x'), 'color', 'red'))
+    c2 = NegatedConjunctiveConditions(c0, c1)
+    assert c2.number_of_conditions == 2