Unit testing json file uploads in flask

Unit testing json upload in flask

Tried adding code snippets which fails

from io import BytesIO

def test_file_upload(client):

    data = {
        'field': 'value',
        'file': (BytesIO(b'FILE CONTENT'), 'test.csv')
    }

    rv = client.post('/upload', buffered=True,
                     content_type='multipart/form-data',
                     data=data)
assert rv.status_code == 200

Want a json file to undergo unit testing