How to Write Mock Object for tempfile NamedTemporaryFile or a file like object

Question

Below is my code : and need to test myfunction(). and how to create mock function of file.

def myfunction(self):
    with tempfile.NamedTemporaryFile() as tf:
        f.seek(0)
        tf.write(f.read())
        tf.flush()
        ocr_content_dict = self.ocr.ocr_document(tf.name, mimetype) or ''
        ocr_content = ocr_content_dict['content']

Answer 1

You can create a mock file object, or you could also use BytesIO / StringIO :

from io import BytesIO

class MockFileObject(object):
    '''
       write mock functions for any that are needed
       DONE: read
       TODO: write
       TODO: seek
       TODO: fileno
       TODO: flush
       TODO: name

       with context manangement use the dunder enter/exit
       TODO: __enter__
       TODO: __exit__

       ... etc
    '''

    def read(self):
        ''' example mock '''
        return BytesIO('some stuff').read()

Usage:

fo = MockFileObject()
with fo as f:
     print(f.read())

output:

some stuff