tail: my solutions :)

tail/tail.py

@@ -0,0 +1,13 @@
+def tail_v1(sequence, count):
+    if count <= 0:
+        return list()
+    return list(sequence[-count:])
+
+
+def tail_v2(sequence, count):
+    if count <= 0:
+        return []
+    return list(list(sequence)[-count:])
+
+
+tail = tail_v2

tail/test_tail.py

@@ -0,0 +1,48 @@
+import unittest
+
+
+from tail import tail
+
+
+class TailTests(unittest.TestCase):
+
+    """Tests for tail."""
+
+    def test_zero(self):
+        self.assertEqual(tail([1, 2], 0), [])
+
+    def test_one(self):
+        self.assertEqual(tail([1, 2], 1), [2])
+
+    def test_two(self):
+        self.assertEqual(tail([1, 2], 2), [1, 2])
+
+    def test_n_larger_than_iterable_length(self):
+        nums = [1, 2, 3, 4]
+        self.assertEqual(tail(nums, 5), [1, 2, 3, 4])
+        self.assertEqual(tail([], 10), [])
+
+    def test_string(self):
+        self.assertEqual(tail("hello", 2), ["l", "o"])
+
+    def test_tuple(self):
+        self.assertEqual(tail((1, 2, 3), 3), [1, 2, 3])
+
+    # To test the Bonus part of this exercise, comment out the following line
+    def test_negative_n(self):
+        nums = [1, 2, 3, 4]
+        self.assertEqual(tail(nums, -1), [])
+        self.assertEqual(tail((), -9), [])
+
+    # To test the Bonus part of this exercise, comment out the following line
+    def test_iterator(self):
+        nums = (n ** 2 for n in [1, 2, 3, 4])
+        self.assertEqual(tail(nums, -1), [])  # Don't loop for negative n
+        self.assertEqual(tail(nums, 0), [])  # Don't loop for n=0
+        self.assertEqual(tail(nums, 2), [9, 16])  # Consuming the generator
+        self.assertEqual(list(nums), [])  # The nums generator is now empty
+        self.assertEqual(tail(nums, 1), [])  # n=1 with a now empty generator
+
+
+if __name__ == "__main__":
+    unittest.main(verbosity=2)