On Wed, Oct 18, 2017 at 9:50 PM, Sam Lee <skyn...@gmail.com> wrote:
> Thank you.
> I didn't even post stacktrace and those were the exact errors!!
because I've gotten them before and I knew from your description what
you were seeing, they are very specific to what psycopg2 is doing.
> I'll take a look at test/engine/test_reconnect.py and probably test against
> Pool directly.
> What I'm testing is a bit silly cause I'm testing sqlalchemy behavior :P
enjoy
>
> Thanks.
> Sam
>
>
>
> On Tue, Oct 17, 2017 at 10:21 PM, Mike Bayer <mike...@zzzcomputing.com>
> wrote:
>>
>> On Tue, Oct 17, 2017 at 4:58 PM, Sam Lee <skyn...@gmail.com> wrote:
>> > Hi,
>> >
>> > I am passing a custom creator to sqlalchemy.create_engine().
>> > And, I want to simulate the following scenario in automated test without
>> > using actual database connection:
>> >
>> > 1. Request a connection from pool: connects to DB.
>> > 2. DB goes down.
>> > 3. Request a connection from pool: connection is invalid.
>> > 4. Request a connection from pool: connects to DB again.
>> >
>> > I'm trying the following testcase:
>> >
>> > def mycreator():
>> > print('called')
>> > # return psycopg2.connect(....)
>> > return unittest.mock.MagicMock()
>> >
>> > engine = create_engine('postgresql://', creator=mycreator,
>> > pool_size=1)
>> > c = engine.connect() # calls mycreator
>> > c.close() # connection returned to pool
>> > c = engine.connect() # does not call mycreator (reuses
>> > connection
>> > in pool)
>> > c.invalidate()
>> > c.close()
>> > c = engine.connect() # calls mycreator (because connection is
>> > invalidated)
>> >
>> >
>> > But, it throws exception because MagicMock isn't cursor or connection.
>>
>> I'm assuming you are getting this error from psycopg2 itself. To
>> use create_engine(), you'd need to mock whatever is being called that
>> is not compatible, which here I am assuming are things like
>> psycopg2.extensions.register_type,
>> psycopg2.extras.register_default_json, and others. Patch these with
>> mocks so that they have no effect.
>>
>> However, if your test is just looking for the behavior of the pool,
>> then test against a QueuePool directly.
>>
>> The tests in test/engine/test_reconnect.py make extensive use of mocks
>> to simulate disconnects though most of the create_engine() integration
>> is done using real database connections with a patch to close out the
>> DBAPI connection to simulate a disconnect.
>>
>>
>> > What kind of mock or fake connection object should mycreator return in
>> > the
>> > test
>> > so that above snippet will behave as I expect it to, calling mycreator
>> > twice?
>> > (Using actual connection, psycopg2.connect(), works as expected).
>> >
>> > Thanks.
>> > Sam
>> >
>> > --
>> > SQLAlchemy -
>> > The Python SQL Toolkit and Object Relational Mapper
>> >
>> > http://www.sqlalchemy.org/
>> >
>> > To post example code, please provide an MCVE: Minimal, Complete, and
>> > Verifiable Example. See http://stackoverflow.com/help/mcve for a full
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>> --
>> SQLAlchemy -
>> The Python SQL Toolkit and Object Relational Mapper
>>
>> http://www.sqlalchemy.org/
>>
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>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> description.
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--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
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