euivalence test, op format doc

tests/test_circuit.py

@@ -131,7 +131,14 @@ def test_pickle(mydir):
     cs = pickle.dumps(c)
     assert cs is not None
     c2 = pickle.loads(cs)
-    assert c == c2
+    assert len(c.nodes) == len(c2.nodes)
+
+def test_equivalency():
+    c1 = bench.parse('input(a) output(z) z=not(a)')
+    c2 = bench.parse('input(a) output(z) z=not(a)')
+    assert c1 != c2
+    assert c1.lines[0] != c2.lines[0]
+    assert c1.nodes[0] != c2.nodes[0]
 
 
 def test_substitute():