New exercise: ocr numbers

EXERCISES.txt

@@ -9,6 +9,7 @@ nucleotide-count
 series
 largest-series-product
 octal
+ocr-numbers
 difference-of-squares
 point-mutations
 phone-number

ocr-numbers/example.py

@@ -0,0 +1,16 @@
+def number(g):
+    if not g or len(g) < 4 or any(len(r)!=len(g[0]) for r in g):
+        raise ValueError('Ill-formed grid')
+    if g == [" _ ","| |","|_|","   "]:
+        return '0'
+    elif g == ["   ","  |","  |","   "]:
+        return '1'
+    else:
+        return '?'
+
+def grid(n):
+    if n == '0':
+        return [" _ ","| |","|_|","   "]
+    elif n == '1':
+        return ["   ","  |","  |","   "]
+    raise ValueError('Unknown digit')

ocr-numbers/ocr_test.py

@@ -0,0 +1,56 @@
+try:
+    from ocr import number, grid
+except ImportError:
+    raise SystemExit('Could not find ocr.py. Does it exist?')
+
+import unittest
+
+class OcrTest(unittest.TestCase):
+    def test_0(self):
+        self.assertEqual('0', number([" _ ","| |","|_|","   "]))
+
+    @unittest.skip("Not implemented yet")
+    def test_1(self):
+        self.assertEqual('1', number(["   ","  |","  |","   "]))
+
+    @unittest.skip("Not implemented yet")
+    def test_garbage(self):
+        self.assertEqual('?', number([" _ "," _|","  |","   "]))
+
+    @unittest.skip("Not implemented yet")
+    def test_last_line_nonblank(self):
+        self.assertEqual('?', number(["   ","  |","  |","| |"]))
+
+    @unittest.skip("Not implemented yet")
+    def test_unknown_char(self):
+        self.assertEqual('?', number([" - "," _|"," X|","   "]))
+
+    @unittest.skip("Not implemented yet")
+    def test_too_short_row(self):
+        with self.assertRaises(ValueError) as context:
+            number(["   "," _|"," |","   "])
+        self.assertEqual(context.exception.message, 'Ill-formed grid')
+
+    @unittest.skip("Not implemented yet")
+    def test_insufficient_rows(self):
+        with self.assertRaises(ValueError) as context:
+            number(["   "," _|"," X|"])
+        self.assertEqual(context.exception.message, 'Ill-formed grid')
+
+    @unittest.skip("Not implemented yet")
+    def test_grid0(self):
+        self.assertEqual([" _ ","| |","|_|","   "], grid('0'))
+
+    @unittest.skip("Not implemented yet")
+    def test_grid1(self):
+        self.assertEqual(["   ","  |","  |","   "], grid('1'))
+
+    @unittest.skip("Not implemented yet")
+    def test_invalid_digit(self):
+        with self.assertRaises(ValueError) as context:
+            grid('2')
+        self.assertEqual(context.exception.message, 'Unknown digit')
+
+
+if __name__ == '__main__':
+    unittest.main()