from mock import patch, mock_open

proc_data = """   8       0 sda 2247890 261640 106278904 1171596
        27420712 26940332 2070154732 47610592 0 7245308 48791236"""


print 'Lines:'
with patch('__main__.open', mock_open(read_data=proc_data), create=True):
    with open('foo', 'r') as fh:
        for line in fh:
            print line

print ''
print 'Read:'
with patch('__main__.open', mock_open(read_data=proc_data), create=True):
    with open('foo', 'r') as fh:
        print fh.read()


# Output:
# Lines:
#
# Read:
#    8       0 sda 2247890 261640 106278904 1171596
#         27420712 26940332 2070154732 47610592 0 7245308 48791236