email_check.py

import unittest

# Fake the env.
class ValidationError(Exception): pass
self = type('Test', (object,), {"error_messages": {'invalid': 'ERROR'}})


def is_email(email):
    email_bits = email.split('@')
    
    if len(email_bits) != 2:
        raise ValidationError(self.error_messages['invalid'])
    
    if len(email_bits[0]) < 1:
        raise ValidationError(self.error_messages['invalid'])
    
    domain_bits = email_bits[1].split('.')
    
    if len(domain_bits) < 2:
        raise ValidationError(self.error_messages['invalid'])
    
    if not len(domain_bits[-1]) > 2:
        raise ValidationError(self.error_messages['invalid'])
    
    for bit in domain_bits:
        if len(bit) < 1:
            raise ValidationError(self.error_messages['invalid'])
        
        if not bit[0].isalnum() or not bit[-1].isalnum():
            raise ValidationError(self.error_messages['invalid'])
    
    return email


class EmailTestCase(unittest.TestCase):
    def test_valid_addresses(self):
        addresses = [
            '[email protected]',
            '[email protected]',
            '[email protected]',
            '[email protected]',
            '[email protected]',
        ]
        
        for addy in addresses:
            self.assertEqual(is_email(addy), addy)
    
    def test_invalid_addresses(self):
        addresses = [
            'daniel',
            'daniel@',
            '@local.com',
            '[email protected]',
            '[email protected]',
            
            '',
            'foo@bar',
            '[email protected]',
            '[email protected]',
            '[email protected]',
            '[email protected]',
        ]
        
        for addy in addresses:
            try:
                is_email(addy)
                self.fail(addy)
            except ValidationError:
                # Supposed to fail.
                pass


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