diff --git a/test.py b/test.py
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+++ b/test.py
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+# test.py
+# Eryn Wells <eryn@erynwells.me>
+'''
+Unit tests for tictactoe.
+'''
+
+import unittest
+from tictactoe import Board
+
+class BoardTests(unittest.TestCase):
+    def test_default_is_empty(self):
+        b = Board()
+        self.assertTrue(b.empty)
+        self.assertFalse(b.full)
+        self.assertEqual(b.next_player, Board.X)
+
+    def test_winner(self):
+        wins = [
+            # Rows.
+            'xxx o o o',
+            'oo xxxo  ',
+            'o o o xxx',
+            # Columns.
+            'xooxo x  ',
+            'oxo xo x ',
+            'o xo x ox',
+            # Diagonals.
+            'xo ox  ox',
+            'o xox x o',
+        ]
+        for b in wins:
+            with self.subTest(board=b):
+                board = Board(b)
+                self.assertEqual(board.winner, Board.X, 'expected X to win\n{}'.format(board))
+
+        table = str.maketrans('xo', 'ox')
+        wins = [b.translate(table) for b in wins]
+        for b in wins:
+            with self.subTest(board=b):
+                board = Board(b)
+                self.assertEqual(board.winner, Board.O, 'expected O to win\n{}'.format(board))
+
+def main():
+    unittest.main()
+
+if __name__ == '__main__':
+    main()