implement conversion to arbitrary prefixes

cashaddress/convert.py

@@ -43,12 +43,18 @@ def legacy_address(self):
         version_int = Address._address_type('legacy', self.version)[1]
         return b58encode_check(Address.code_list_to_string([version_int] + self.payload))
 
-    def cash_address(self):
+    def cash_address(self, prefix=None):
+        prefix = prefix if prefix is not None else self.prefix
+        self._check_case(prefix)
+        is_uppercase = prefix == prefix.upper()
         version_int = Address._address_type('cash', self.version)[1]
         payload = [version_int] + self.payload
         payload = convertbits(payload, 8, 5)
-        checksum = calculate_checksum(self.prefix, payload)
-        return self.prefix + ':' + b32encode(payload + checksum)
+        checksum = calculate_checksum(prefix, payload)
+        address_string = prefix + ':' + b32encode(payload + checksum)
+        if is_uppercase:
+            return address_string.upper()
+        return address_string
 
     @staticmethod
     def code_list_to_string(code_list):
@@ -94,8 +100,7 @@ def _legacy_string(address_string):
 
     @staticmethod
     def _cash_string(address_string):
-        if address_string.upper() != address_string and address_string.lower() != address_string:
-            raise InvalidAddress('Cash address contains uppercase and lowercase characters')
+        Address._check_case(address_string)
         address_string = address_string.lower()
         colon_count = address_string.count(':')
         if colon_count == 0:
@@ -113,6 +118,11 @@ def _cash_string(address_string):
         payload = converted[1:-6]
         return Address(version, payload, prefix)
 
+    @staticmethod
+    def _check_case(text):
+        if text.upper() != text and text.lower() != text:
+            raise InvalidAddress('Cash address contains uppercase and lowercase characters')
+
 
 def to_cash_address(address):
     return Address.from_string(address).cash_address()

tests/test.py

@@ -1,6 +1,7 @@
 import unittest
 
 from cashaddress import convert
+from cashaddress.convert import Address, InvalidAddress
 
 
 class TestConversion(unittest.TestCase):
@@ -61,5 +62,42 @@ def test_is_valid(self):
         self.assertFalse(convert.is_valid(False))
         self.assertFalse(convert.is_valid('Hello World!'))
 
+    def test_prefixes(self):
+        """Test a few identical addresses with different CashAddr prefixes"""
+        legacy_address = "1NLcNpAaBBMekgBZk7NxwdxwtSUTfTV8Aq"
+        addr = Address.from_string(legacy_address)
+        default_prefix = addr.prefix
+        self.assertEqual(default_prefix, Address.MAINNET_PREFIX)
+        self.assertEqual(addr.cash_address(),
+                         'bitcoincash:qr4pqy6q4cy2d50zpaek57nnrja7289fkskz6jm7yf')
+        self.assertEqual(addr.cash_address(prefix='abc'),
+                         'abc:qr4pqy6q4cy2d50zpaek57nnrja7289fksqt4c50w9')
+        self.assertEqual(addr.cash_address(prefix='simpleledger'),
+                         'simpleledger:qr4pqy6q4cy2d50zpaek57nnrja7289fks6e3fw76h')
+
+        regtest_address = 'regtest:qr4pqy6q4cy2d50zpaek57nnrja7289fksjm6es9se'
+        addr2 = Address.from_string(regtest_address)
+        self.assertEqual(addr2.legacy_address(), legacy_address)
+        # The prefix defaults to the one in the input string.
+        self.assertEqual(addr2.prefix, 'regtest')
+        self.assertEqual(addr2.cash_address(), regtest_address)
+
+    def test_prefix_case(self):
+        with self.assertRaises(InvalidAddress):
+            Address.from_string(
+                'rEgTeSt:qr4pqy6q4cy2d50zpaek57nnrja7289fksjm6es9se')
+        with self.assertRaises(InvalidAddress):
+            Address.from_string(
+                'regtest:QR4PQY6Q4CY2D50ZPAEK57NNRJA7289FKSJM6ES9SE')
+
+        addr = Address.from_string('regtest:qr4pqy6q4cy2d50zpaek57nnrja7289fksjm6es9se')
+        # The address should take the same case as the specified prefix
+        self.assertEqual(addr.cash_address(prefix="SLP"),
+                         'SLP:QR4PQY6Q4CY2D50ZPAEK57NNRJA7289FKSWF89PY2G')
+        # Do not allow mixed-case prefixes
+        with self.assertRaises(InvalidAddress):
+            addr.cash_address(prefix="sLp")
+
+
 if __name__ == '__main__':
     unittest.main()