
MongoDB test layer » master/slave setup
***************************************

Note: To run this test:

     bin/buildout install mongodb mongodb-test
     bin/test-mongodb --test=mongodb_masterslave


Introduction
============

For information about MongoDB see:http://en.wikipedia.org/wiki/Mongodb

The "MongoMasterSlaveLayer" starts and stops multiple MongoDB
instances and configures a master-slave connection between them.


Master/Slave
============


Warming up
----------

We create a new MongoDB layer:

   >>> from lovely.testlayers import mongodb
   >>> masterslave = mongodb.MongoMasterSlaveLayer('mongodb.masterslave', mongod_bin = project_path('bin', 'mongod'))
   >>> masterslave.storage_ports
   [37020, 37021, 37022]

So let's bootstrap the servers:

   >>> from zope.testrunner.runner import gather_layers
   >>> layers = []
   >>> gather_layers(masterslave, layers)
   >>> for layer in layers:
   ...     layer.setUp()


Getting real
------------

Connect to it using a real MongoDB client:

   >>> from pymongo import Connection, ReadPreference
   >>> from pymongo.master_slave_connection import MasterSlaveConnection
   >>> mongo_conn = MasterSlaveConnection(
   ...     Connection('localhost:37020', safe=True, w=3),
   ...     [
   ...         Connection('localhost:37021', read_preference = ReadPreference.SECONDARY),
   ...         Connection('localhost:37022', read_preference = ReadPreference.SECONDARY),
   ...     ]
   ... )
   >>> mongo_db = mongo_conn['bar-db']

Query operation counters upfront to compare them later:

   >>> opcounters_before = masterslave.get_opcounters()['custom']

Insert some data:

   >>> document_id = mongo_db.foobar.insert({'hello': 'world'})
   >>> document_id
   ObjectId('...')

And query it:

   >>> document = mongo_db.foobar.find_one(document_id)
   >>> document
   {u'_id': ObjectId('...'), u'hello': u'world'}

Prove that the "write" operation was dispatched to the "PRIMARY",
while the "read" operation was dispatched to any "SECONDARY":

   >>> opcounters_after = masterslave.get_opcounters()['custom']

   >>> opcounters_after['primary.insert'] == opcounters_before['primary.insert'] + 1
   True

   >>> assert \
   ...     opcounters_after['secondary.query'] == opcounters_before['secondary.query'] + 1, \
   ...     "ERROR: expected 'after == before + 1', but got 'after=%s, before=%s'" % \
   ...         (opcounters_after['secondary.query'], opcounters_before['secondary.query'])


Clean up
--------


Database
~~~~~~~~

>>> mongo_conn.drop_database('bar-db')
>>> mongo_conn.disconnect()
>>> del mongo_conn
>>> del mongo_db


Layers
~~~~~~

Connections are refused after teardown:

   >>> for layer in layers:
   ...     layer.tearDown()

   >>> def check_down(*ports):
   ...     for port in ports:
   ...         try:
   ...             tn = telnetlib.Telnet('localhost', port)
   ...             tn.close()
   ...         except:
   ...             yield True

   >>> all(check_down(masterslave.storage_ports))
   True
