--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/purple/tests/test_switch.py	Tue Nov 26 21:16:32 2013 -0600
@@ -0,0 +1,83 @@
+# Copyright (C) 2013 by Brian Neal.
+# This file is part of purple, the PURPLE (Cipher Machine 97) simulation.
+# purple is released under the MIT License (see LICENSE.txt).
+
+import unittest
+
+from purple.switch import SteppingSwitch, SteppingSwitchError, create_switch
+import purple.switch
+
+
+class SwitchTestCase(unittest.TestCase):
+
+    def test_construction(self):
+
+        bad_wiring = [
+            [1, 2, 0],
+            [2, 1],
+            [0, 1, 2]
+        ]
+        good_wiring = [
+            [1, 2, 0],
+            [2, 1, 0],
+            [0, 1, 2]
+        ]
+        self.assertRaises(SteppingSwitchError, SteppingSwitch, bad_wiring)
+        self.assertRaises(SteppingSwitchError, SteppingSwitch, bad_wiring, 0)
+        self.assertRaises(SteppingSwitchError, SteppingSwitch, good_wiring, -1)
+        self.assertRaises(SteppingSwitchError, SteppingSwitch, good_wiring, 3)
+        self.assertRaises(SteppingSwitchError, SteppingSwitch, bad_wiring, 3)
+
+    def test_bad_set_pos(self):
+
+        switch = create_switch(purple.switch.SIXES)
+        self.assertRaises(SteppingSwitchError, switch.set_pos, -1)
+        self.assertRaises(SteppingSwitchError, switch.set_pos, 25)
+        self.assertRaises(SteppingSwitchError, switch.set_pos, 26)
+
+    def test_set_pos(self):
+
+        switch = create_switch(purple.switch.SIXES)
+        for pos in range(25):
+            switch.set_pos(pos)
+
+    def test_step(self):
+
+        switch = create_switch(purple.switch.SIXES)
+        for n in range(25 * 2 + 1):
+            pos = n % 25
+            self.assertEqual(switch.pos, pos)
+            switch.step()
+
+    def test_output(self):
+
+        switch = create_switch(purple.switch.SIXES)
+        switch.set_pos(0)
+        self.assertEqual(switch[0], 1)
+        self.assertEqual(switch[1], 0)
+        self.assertEqual(switch[2], 2)
+        self.assertEqual(switch[3], 4)
+        self.assertEqual(switch[4], 3)
+        self.assertEqual(switch[5], 5)
+
+        switch.step()
+        self.assertEqual(switch[0], 5)
+        self.assertEqual(switch[1], 2)
+        self.assertEqual(switch[2], 4)
+        self.assertEqual(switch[3], 1)
+        self.assertEqual(switch[4], 0)
+        self.assertEqual(switch[5], 3)
+
+        switch.set_pos(24)
+        self.assertEqual(switch[0], 4)
+        self.assertEqual(switch[1], 1)
+        self.assertEqual(switch[2], 3)
+        self.assertEqual(switch[3], 2)
+        self.assertEqual(switch[4], 5)
+        self.assertEqual(switch[5], 0)
+
+    def test_bad_create_switch(self):
+
+        self.assertRaises(ValueError, create_switch, -1)
+        self.assertRaises(ValueError, create_switch, 4)
+        self.assertRaises(ValueError, create_switch, 99)