File-like object for reading random data (usefull for testing)

FakeReadOnlyBinaryFile.py

import random

def rnd_byte():
    return chr(random.randint(0, 255))

class FakeReadOnlyBinaryFile:
    """
    File-like object for reading random data. The ammount of data to generate
    is specified when the object is created.
    
    Usage:
        file_like_object = FakeReadOnlyBinaryFile(1024 * 1024)
    
    The file_like_object  will provide 1MiB of random data.
    """
    def __init__(self, size):
        self.size = size
        self.read_count = 0
    
    # http://docs.python.org/release/2.5.2/lib/bltin-file-objects.html
    
    def close(self):
        pass # no-op
        
    def flush(self):
        pass # no-op
        
    def next(self):
        return self.readline()
    
    def read(self, size=-1):
        if self.read_count >= self.size:
            return ''
        
        if size == -1:
            size = self.size - self.read_count
        
        if size+self.read_count > self.size:
            size = self.size - self.read_count
        
        self.read_count = self.read_count + size
        
        byte_list = [rnd_byte() for random_int in range(0, size)]
        return ''.join(byte_list)
        
    def readline(self):
        return self.read().replace('\n', '\x00')
        
    def readlines(self):
        return self.read().split()
        
    def xreadlines(self):
        raise(IOError("xreadlines() isn't implemented"))
        
    def seek(self, offset, whence=None):
        raise(IOError("seek() isn't implemented"))
        
    def tell(self):
        raise(IOError("tell() isn't implemented"))
        
    def truncate(self, size=None):
        raise(IOError("File not open for writing"))
        
    def write(self):
        raise(IOError("File not open for writing"))
        
    def writelines(self):
        raise(IOError("File not open for writing"))
    
    #def fileno(self):
    #    pass
    
    #def isatty(self):
    #    pass

if __name__ == '__main__':
	import pprint
	f = FakeReadOnlyBinaryFile(256)
	pprint.pprint(f.read(1024))