TDD in Python

TDD.py

"""Convert to and from Roman numerals"""

#-------------------------------------------------------------------------------
#
# http://woodpecker.org.cn/diveintopython/unit_testing/stage_1.html
#
#-------------------------------------------------------------------------------

import re

#Define exceptions
class RomanError(Exception): pass
class OutOfRangeError(RomanError): pass
class NotIntegerError(RomanError): pass
class InvalidRomanNumeralError(RomanError): pass

#Define digit mapping
romanNumeralMap = (('M',  1000),
                   ('CM', 900),
                   ('D',  500),
                   ('CD', 400),
                   ('C',  100),
                   ('XC', 90),
                   ('L',  50),
                   ('XL', 40),
                   ('X',  10),
                   ('IX', 9),
                   ('V',  5),
                   ('IV', 4),
                   ('I',  1))

def toRoman(n):
    """convert integer to Roman numeral"""
    if not (0 < n < 4000):
        raise OutOfRangeError, "number out of range (must be 1..3999)"
    if int(n) <> n:
        raise NotIntegerError, "non-integers can not be converted"

    result = ""
    for numeral, integer in romanNumeralMap:
        while n >= integer:
            result += numeral
            n -= integer
    return result

#Define pattern to detect valid Roman numerals
romanNumeralPattern = '^M?M?M?(CM|CD|D?C?C?C?)(XC|XL|L?X?X?X?)(IX|IV|V?I?I?I?)$' 1

def fromRoman(s):
    """convert Roman numeral to integer"""
    if not re.search(romanNumeralPattern, s):                                    2
        raise InvalidRomanNumeralError, 'Invalid Roman numeral: %s' % s

    result = 0
    index = 0
    for numeral, integer in romanNumeralMap:
        while s[index:index+len(numeral)] == numeral:
            result += integer
            index += len(numeral)
    return result

Unit_testing.py

"""Unit test for roman.py"""

import roman
import unittest

class KnownValues(unittest.TestCase):                          
    knownValues = ( (1, 'I'),
                    (2, 'II'),
                    (3, 'III'),
                    (4, 'IV'),
                    (5, 'V'),
                    (6, 'VI'),
                    (7, 'VII'),
                    (8, 'VIII'),
                    (9, 'IX'),
                    (10, 'X'),
                    (50, 'L'),
                    (100, 'C'),
                    (500, 'D'),
                    (1000, 'M'),
                    (31, 'XXXI'),
                    (148, 'CXLVIII'),
                    (294, 'CCXCIV'),
                    (312, 'CCCXII'),
                    (421, 'CDXXI'),
                    (528, 'DXXVIII'),
                    (621, 'DCXXI'),
                    (782, 'DCCLXXXII'),
                    (870, 'DCCCLXX'),
                    (941, 'CMXLI'),
                    (1043, 'MXLIII'),
                    (1110, 'MCX'),
                    (1226, 'MCCXXVI'),
                    (1301, 'MCCCI'),
                    (1485, 'MCDLXXXV'),
                    (1509, 'MDIX'),
                    (1607, 'MDCVII'),
                    (1754, 'MDCCLIV'),
                    (1832, 'MDCCCXXXII'),
                    (1993, 'MCMXCIII'),
                    (2074, 'MMLXXIV'),
                    (2152, 'MMCLII'),
                    (2212, 'MMCCXII'),
                    (2343, 'MMCCCXLIII'),
                    (2499, 'MMCDXCIX'),
                    (2574, 'MMDLXXIV'),
                    (2646, 'MMDCXLVI'),
                    (2723, 'MMDCCXXIII'),
                    (2892, 'MMDCCCXCII'),
                    (2975, 'MMCMLXXV'),
                    (3051, 'MMMLI'),
                    (3185, 'MMMCLXXXV'),
                    (3250, 'MMMCCL'),
                    (3313, 'MMMCCCXIII'),
                    (3408, 'MMMCDVIII'),
                    (3501, 'MMMDI'),
                    (3610, 'MMMDCX'),
                    (3743, 'MMMDCCXLIII'),
                    (3844, 'MMMDCCCXLIV'),
                    (3888, 'MMMDCCCLXXXVIII'),
                    (3940, 'MMMCMXL'),
                    (3999, 'MMMCMXCIX'))                       

    def testToRomanKnownValues(self):                          
        """toRoman should give known result with known input"""
        for integer, numeral in self.knownValues:              
            result = roman.toRoman(integer)                    
            self.assertEqual(numeral, result)                  

    def testFromRomanKnownValues(self):                          
        """fromRoman should give known result with known input"""
        for integer, numeral in self.knownValues:                
            result = roman.fromRoman(numeral)                    
            self.assertEqual(integer, result)                    

class ToRomanBadInput(unittest.TestCase):                            
    def testTooLarge(self):                                          
        """toRoman should fail with large input"""                   
        self.assertRaises(roman.OutOfRangeError, roman.toRoman, 4000)

    def testZero(self):                                              
        """toRoman should fail with 0 input"""                       
        self.assertRaises(roman.OutOfRangeError, roman.toRoman, 0)   

    def testNegative(self):                                          
        """toRoman should fail with negative input"""                
        self.assertRaises(roman.OutOfRangeError, roman.toRoman, -1)  

    def testNonInteger(self):                                        
        """toRoman should fail with non-integer input"""             
        self.assertRaises(roman.NotIntegerError, roman.toRoman, 0.5) 

class FromRomanBadInput(unittest.TestCase):                                      
    def testTooManyRepeatedNumerals(self):                                       
        """fromRoman should fail with too many repeated numerals"""              
        for s in ('MMMM', 'DD', 'CCCC', 'LL', 'XXXX', 'VV', 'IIII'):             
            self.assertRaises(roman.InvalidRomanNumeralError, roman.fromRoman, s)

    def testRepeatedPairs(self):                                                 
        """fromRoman should fail with repeated pairs of numerals"""              
        for s in ('CMCM', 'CDCD', 'XCXC', 'XLXL', 'IXIX', 'IVIV'):               
            self.assertRaises(roman.InvalidRomanNumeralError, roman.fromRoman, s)

    def testMalformedAntecedent(self):                                           
        """fromRoman should fail with malformed antecedents"""                   
        for s in ('IIMXCC', 'VX', 'DCM', 'CMM', 'IXIV',
                  'MCMC', 'XCX', 'IVI', 'LM', 'LD', 'LC'):                       
            self.assertRaises(roman.InvalidRomanNumeralError, roman.fromRoman, s)

class SanityCheck(unittest.TestCase):        
    def testSanity(self):                    
        """fromRoman(toRoman(n))==n for all n"""
        for integer in range(1, 4000):       
            numeral = roman.toRoman(integer) 
            result = roman.fromRoman(numeral)
            self.assertEqual(integer, result)

class CaseCheck(unittest.TestCase):                   
    def testToRomanCase(self):                        
        """toRoman should always return uppercase"""  
        for integer in range(1, 4000):                
            numeral = roman.toRoman(integer)          
            self.assertEqual(numeral, numeral.upper())

    def testFromRomanCase(self):                      
        """fromRoman should only accept uppercase input"""
        for integer in range(1, 4000):                
            numeral = roman.toRoman(integer)          
            roman.fromRoman(numeral.upper())          
            self.assertRaises(roman.InvalidRomanNumeralError,
                              roman.fromRoman, numeral.lower())

if __name__ == "__main__":
    unittest.main()