docs: update Proof of Potato model to v0.2

tests/test_pop_simulation.py

@@ -0,0 +1,35 @@
+"""Tests of illustrative, non-consensus simulation only."""
+import sys
+import unittest
+from pathlib import Path
+sys.path.insert(0, str(Path(__file__).resolve().parents[1] / 'scripts'))
+from simulate_pop_v02 import fee_example, progressive_example, qualify, simulate
+import random
+
+
+class FeeAndSimulationTests(unittest.TestCase):
+    def test_example_fees_monotonic(self):
+        for reward in (0, 1, 10, 100, 1000):
+            self.assertEqual(fee_example(1, reward), 0)
+            self.assertGreater(fee_example(3, reward), fee_example(2, reward))
+        self.assertLess(progressive_example(0), progressive_example(100))
+
+    def test_no_ticket_when_probability_zero(self):
+        self.assertEqual(qualify(random.Random(1), 3, 0, 100),
+                         (False, fee_example(2, 100) + fee_example(3, 100)))
+
+    def test_free_win_ends_without_fee(self):
+        self.assertEqual(qualify(random.Random(1), 3, 1, 100), (True, 0))
+
+    def test_reproducible(self):
+        a = simulate(5, 100, 123, .7, 2, 50)
+        b = simulate(5, 100, 123, .7, 2, 50)
+        self.assertEqual(a, b)
+
+    def test_invalid_windows(self):
+        with self.assertRaises(ValueError):
+            fee_example(4, 1)
+
+
+if __name__ == '__main__':
+    unittest.main()