a hash curiosity

test_ipfs.py

from hashlib import sha256                                                                             
import multihash                                                                                       
from multihash import SHA2_256                                                                         
from base58 import b58encode                                                                           
import subprocess                                                                                      
                                                                                                       
class IPFS_interface(unittest.TestCase):                                                               
                                                                                                       
    def test_hash_expectations(self):                                                                  
                                                                                                       
        # add 'hello world' to ipfs, get resulting hash                                                
        ps = subprocess.Popen(['ipfs', 'add'], stdin=subprocess.PIPE, stdout=subprocess.PIPE)          
        output = ps.communicate(input=b'hello world')[0]                                               
        ipfs_hash = output.decode('ascii').split()[1]                                                  
                                                                                                       
        # retrieve ipfs object for 'hello world'                                                       
        proc = subprocess.run(['ipfs', 'object', 'get', ipfs_hash, '--encoding', 'protobuf'], stdout=subprocess.PIPE)   
                                                                                                       
        # hash it                                                                                      
        hasher = sha256()                                                                              
        hasher.update(proc.stdout)                                                                     
        my_hash = b58encode(bytes(multihash.encode(hasher.digest(), SHA2_256)))                        
                                                                                                       
        # they should be equal                                                                         
        self.assertEqual(ipfs_hash, my_hash, "I assume that the ipfs hash is a base58 encoded SHA2_256 multihash of the protobuf for the ipfs object (i.e. data plus links")
                                                                                                       
        #AssertionError: 'Qmf412jQZiuVUtdgnB36FXFX7xg5V6KEbSJ4dpQuhkLyfD' != 'QmcxynZDK7xyC5BrUNjGFyf62w99oVoxf62CSLJfDvt3NC'