[TIP] Mocking a cursor for use with Psycopg2

[Patrick Smith]

If I understand correctly, what you want is a mock object that is iterable.
You can accomplish this using a MagicMock and setting the return value for
`__iter__`. For example:


    from mock import MagicMock

    cur = MagicMock()
    cur.__iter__.return_value = ['result 1', 'result 2']


Now, in your code under test, you can use the mock object to record the
function call and also iterate over the results:


    cur.execute('SELECT * FROM test;')
    for record in cur:
        print record


This code will print:


    result 1
    result 2


And you can still make any desired assertions about the recorded calls:


    cur.execute.assert_called_once_with('SELECT * FROM test;')


Hope this helps,

Patrick Smith


On Thu, Mar 13, 2014 at 12:29 PM, Alexander Bandukwala <7h3kk1d at gmail.com>wrote:

> I'm trying to mock access to my postgres database using the mock
> framework. I saw the cursor example here<http://mock.readthedocs.org/en/latest/getting-started.html?highlight=cursor#setting-return-values-and-attributes>.
> The psycopg2 cursor however does not return the data set but is iterated
> over example here <http://initd.org/psycopg/docs/cursor.html> under
> result retrieval methods. What would be the best way to mock a cursor which
> can be called with a function but also be iterated over.
>
> Thanks for any assistance and sorry for the inexperienced question.
>
> --
> Alexander Bandukwala
> 337-335-0133
> Twitter: http://twitter.com/abanduk
> Site: http://bandukwala.me
>
>
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