tests: Lots of fixes

Thanks to the great work done by Gökhan Göktürk.

tests/graphtest.py

@@ -6,17 +6,17 @@ from pisi import graph
 class GraphTestCase(unittest.TestCase):
     def setUp(self):
         self.g0 = pisi.graph.Digraph()
-        self.g0.add_edge(self,(1,2))
-        self.g0.add_edge(self,(1,3))
-        self.g0.add_edge(self,(2,3))
-        self.g0.add_edge(self,(3,4))
-        self.g0.add_edge(self,(4,1))
+        self.g0.add_edge(1,2)
+        self.g0.add_edge(1,3)
+        self.g0.add_edge(2,3)
+        self.g0.add_edge(3,4)
+        self.g0.add_edge(4,1)
 
         self.g1 = pisi.graph.Digraph()
-        self.g1.add_edge(self,(0,2))
-        self.g1.add_edge(self,(0,3))
-        self.g1.add_edge(self,(2,4))
-        self.g1.add_edge(self,(3,4))
+        self.g1.add_edge(0,2)
+        self.g1.add_edge(0,3)
+        self.g1.add_edge(2,4)
+        self.g1.add_edge(3,4)
 
     def testHasVertex(self):
         assert not self.g0.has_vertex(5)
@@ -28,11 +28,10 @@ class GraphTestCase(unittest.TestCase):
         assert not self.g1.has_edge(2,3)
 
     def testCycle(self):
-        assert self.g0.cycle_free()
+        assert not self.g0.cycle_free()
         assert self.g1.cycle_free()
 
     def testTopologicalSort(self):
         order = self.g1.topological_sort()
-        self.assertEqual(not order[0], 0)
-        self.assertEqual(order[len(order)-1],(3,4))
-
+        assert order[0] == 0
+        assert order[-1] == 4