queen-attack: re-implement according to canonical data 2.1.0

exercises/queen-attack/example.py

@@ -1,27 +1,17 @@
-def board(pos1, pos2):
-    validate_position(pos1, pos2)
-    x1, y1 = pos1
-    x2, y2 = pos2
-    b = [['_'] * 8 for i in range(8)]
-    b[x1][y1] = 'W'
-    b[x2][y2] = 'B'
-    return [''.join(r) for r in b]
+class Queen(object):
+    def __init__(self, row, column):
+        if not 0 <= row <= 7 or not 0 <= column <= 7:
+            raise ValueError("Invalid queen position: queen out of the board")
+        self.row = row
+        self.column = column
 
-
-def can_attack(pos1, pos2):
-    validate_position(pos1, pos2)
-    x1, y1 = pos1
-    x2, y2 = pos2
-    dx = x1 - x2 if x1 >= x2 else x2 - x1
-    dy = y1 - y2 if y1 >= y2 else y2 - y1
-    if dx == dy or dx == 0 or dy == 0:
-        return True
-    return False
-
-
-def validate_position(pos1, pos2):
-    if any(x < 0 or x > 7 for x in pos1 + pos2):
-        raise ValueError('Invalid queen position: queen out of the board')
-    if pos1 == pos2:
-        raise ValueError('Invalid queen position: both queens in the same '
-                         'square: {0}'.format(pos1))
+    def can_attack(self, another_queen):
+        dx = abs(self.row - another_queen.row)
+        dy = abs(self.column - another_queen.column)
+        if dx == dy == 0:
+            raise ValueError(
+                'Invalid queen position: both queens in the same square')
+        elif dx == dy or dx == 0 or dy == 0:
+            return True
+        else:
+            return False

exercises/queen-attack/queen_attack.py

@@ -1,6 +1,6 @@
-def board(white_position, black_position):
-    pass
+class Queen(object):
+    def __init__(self, row, column):
+        pass
 
-
-def can_attack(white_position, black_position):
-    pass
+    def can_attack(self, another_queen):
+        pass

exercises/queen-attack/queen_attack_test.py

@@ -1,92 +1,61 @@
 import unittest
 
-from queen_attack import board, can_attack
+from queen_attack import Queen
 
 
-# Tests adapted from `problem-specifications//canonical-data.json` @ v2.0.0
+# Tests adapted from `problem-specifications//canonical-data.json` @ v2.1.0
 
 class QueenAttackTest(unittest.TestCase):
 
+    # Test creation of Queens with valid and invalid positions
     def test_queen_valid_position(self):
         try:
-            board((1, 1), (2, 2))
+            Queen(2, 2)
         except ValueError:
             self.fail("Unexpected Exception")
 
     def test_queen_negative_row(self):
         with self.assertRaisesWithMessage(ValueError):
-            board((1, 1), (-2, 2))
+            Queen(-2, 2)
 
     def test_queen_invalid_row(self):
         with self.assertRaisesWithMessage(ValueError):
-            board((1, 1), (8, 4))
+            Queen(8, 4)
 
     def test_queen_negative_column(self):
         with self.assertRaisesWithMessage(ValueError):
-            board((1, 1), (2, -2))
+            Queen(2, -2)
 
     def test_queen_invalid_column(self):
         with self.assertRaisesWithMessage(ValueError):
-            board((1, 1), (4, 8))
+            Queen(4, 8)
 
+    # Test the ability of one queen to attack another
     def test_attack_false(self):
-        self.assertIs(can_attack((2, 4), (6, 6)), False)
+        self.assertIs(Queen(2, 4).can_attack(Queen(6, 6)), False)
 
     def test_attack_same_row(self):
-        self.assertIs(can_attack((2, 4), (2, 6)), True)
+        self.assertIs(Queen(2, 4).can_attack(Queen(2, 6)), True)
 
     def test_attack_same_column(self):
-        self.assertIs(can_attack((4, 5), (2, 5)), True)
+        self.assertIs(Queen(4, 5).can_attack(Queen(2, 5)), True)
 
     def test_attack_diagonal1(self):
-        self.assertIs(can_attack((2, 2), (0, 4)), True)
+        self.assertIs(Queen(2, 2).can_attack(Queen(0, 4)), True)
 
     def test_attack_diagonal2(self):
-        self.assertIs(can_attack((2, 2), (3, 1)), True)
+        self.assertIs(Queen(2, 2).can_attack(Queen(3, 1)), True)
 
     def test_attack_diagonal3(self):
-        self.assertIs(can_attack((2, 2), (1, 1)), True)
+        self.assertIs(Queen(2, 2).can_attack(Queen(1, 1)), True)
 
     def test_attack_diagonal4(self):
-        self.assertIs(can_attack((2, 2), (5, 5)), True)
-
-    # Tests beyond this point are not part of the canonical data.
-
-    # If either board or can_attack are called with an invalid board position
-    # they should raise a ValueError with a meaningful error message.
-    def test_invalid_position_can_attack(self):
-        with self.assertRaisesWithMessage(ValueError):
-            can_attack((0, 0), (7, 8))
-
-    def test_queens_same_position_board(self):
-        with self.assertRaisesWithMessage(ValueError):
-            board((2, 2), (2, 2))
+        self.assertIs(Queen(2, 2).can_attack(Queen(5, 5)), True)
 
+    # Track-specific tests
     def test_queens_same_position_can_attack(self):
         with self.assertRaisesWithMessage(ValueError):
-            can_attack((2, 2), (2, 2))
-
-    def test_board1(self):
-        ans = ['________',
-               '________',
-               '___W____',
-               '________',
-               '________',
-               '______B_',
-               '________',
-               '________']
-        self.assertEqual(board((2, 3), (5, 6)), ans)
-
-    def test_board2(self):
-        ans = ['______W_',
-               '_______B',
-               '________',
-               '________',
-               '________',
-               '________',
-               '________',
-               '________']
-        self.assertEqual(board((0, 6), (1, 7)), ans)
+            Queen(2, 2).can_attack(Queen(2, 2))
 
     # Utility functions
     def setUp(self):