Raise exceptions when trying to initialize nonexistent kanji

kanjicolorizer/colorizer.py

@@ -30,6 +30,7 @@
 import re
 import argparse
 import codecs
+from errno import ENOENT as FILE_NOT_FOUND
 
 # Setup
 
@@ -64,12 +65,26 @@ def __init__(self, character, variant=None):
         字
         >>> k2.variant
         'Kaisho'
+
+        Raises InvalidCharacterError if the character and variant don't
+        correspond to known data
+
+        >>> k = KanjiVG((u'Л'))
+        Traceback (most recent call last):
+            ...
+        InvalidCharacterError: (u'\\u041b', None)
         '''
         self.character = character
         self.variant = variant
-        with codecs.open(os.path.join(source_directory,
-                self.ascii_filename), encoding='utf-8') as f:
-            self.svg = f.read()
+        try:
+            with codecs.open(os.path.join(source_directory,
+                    self.ascii_filename), encoding='utf-8') as f:
+                self.svg = f.read()
+        except IOError as e:  # file not found
+            if e.errno == FILE_NOT_FOUND:
+                raise InvalidCharacterError(character, variant)
+            else:
+                raise
 
     @classmethod
     def _create_from_filename(cls, filename):
@@ -91,11 +106,19 @@ def ascii_filename(self):
         >>> k = KanjiVG(u'漢')
         >>> k.ascii_filename
         '06f22.svg'
+
+        May raise InvalidCharacterError for some kinds of invalid
+        character/variant combinations; this should only happen during
+        object initialization.
         '''
+        try:
+            code = '%05x' % ord(self.character)
+        except TypeError:  # character not a character
+            raise InvalidCharacterError(self.character, self.variant)
         if not self.variant:
-            return '%05x.svg' % ord(self.character)
+            return code + '.svg'
         else:
-            return '%05x-%s.svg' % (ord(self.character), self.variant)
+            return '%s-%s.svg' % (code, self.variant)
 
     @property
     def character_filename(self):
@@ -552,6 +575,26 @@ def _color_generator(self, n):
                 yield self._hsv_to_rgbhexcode(float(i) / n,
                     self.settings.saturation, self.settings.value)
 
+
+# Exceptions
+
+class Error(Exception):
+    '''
+    Base class for this module's exceptions
+    '''
+    pass
+
+
+class InvalidCharacterError(Error):
+    '''
+    Exception thrown when trying to initialize or use a character that
+    there isn't data for
+    '''
+    pass
+
+
+# Test if run
+
 if __name__ == "__main__":
     import doctest
     import sys

kanjicolorizer/tests/test_colorizer.py

@@ -21,6 +21,8 @@
 # <http://www.gnu.org/licenses/>.
 
 import unittest
+from mock import patch
+from kanjicolorizer import colorizer
 from kanjicolorizer.colorizer import KanjiVG
 
 
@@ -62,5 +64,61 @@ def test_valid_variant_contains_named_stroke_group(self):
         k = KanjiVG(u'字', 'Kaisho')
         self.assertIn('kvg:StrokePaths_05b57-Kaisho', k.svg)
 
+    def test_with_invalid_character_raises_correct_ex_args(self):
+        with self.assertRaises(colorizer.InvalidCharacterError) as cm:
+            KanjiVG(u'Л')
+        # args set
+        self.assertEqual(cm.exception.args[0], u'Л')
+        self.assertEqual(cm.exception.args[1], None)
+        # message contains the useful information
+        self.assertIn(repr(u'Л'), repr(cm.exception))
+        self.assertIn(repr(None), repr(cm.exception))
+
+    def test_with_multiple_characters_raises_correct_exception(self):
+        self.assertRaises(
+            colorizer.InvalidCharacterError,
+            KanjiVG,
+            (u'漢字'))
+
+    def test_with_nonexistent_variant_raises_correct_ex_args(self):
+        with self.assertRaises(colorizer.InvalidCharacterError) as cm:
+            KanjiVG(u'字', 'gobbledygook')
+        # args set
+        self.assertEqual(cm.exception.args[0], u'字')
+        self.assertEqual(cm.exception.args[1], 'gobbledygook')
+        # message contains the useful information
+        self.assertIn(repr(u'字'), repr(cm.exception))
+        self.assertIn(repr('gobbledygook'), repr(cm.exception))
+
+    def test_with_mismatched_variant_raises_correct_exception(self):
+        self.assertRaises(
+            colorizer.InvalidCharacterError,
+            KanjiVG,
+            (u'漢', 'Kaisho'))
+
+    def test_empty_variant_raises_correct_exception(self):
+        self.assertRaises(
+            colorizer.InvalidCharacterError,
+            KanjiVG,
+            (u'字', ''))
+
+    def test_with_too_few_parameters_raises_correct_exception(self):
+        self.assertRaises(
+            colorizer.InvalidCharacterError,
+            KanjiVG,
+            ())
+
+    def test_permission_denied_error_propogated(self):
+        '''
+        Errors other than file not found are unknown problems; the
+        exception should not be caught or changed
+        '''
+        with patch('__builtin__.open') as mock_open:
+            mock_open.side_effect = IOError(31, 'Permission denied')
+            self.assertRaises(
+                IOError,
+                KanjiVG,
+                ('a'))
+
 if __name__ == "__main__":
     unittest.main()