Commit 0707db25 authored by Tres Seaver's avatar Tres Seaver

Make the ZODB-dependent functest of persistent.wref into standalone doctests.

Put them inside ZODB/tests in anticipation of separating persistent from
ZODB.
parent 664e3f7e
##############################################################################
#
# Copyright (c) 2003 Zope Foundation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL). A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
"""ZODB-based (functional) tests persistent weakrefs
"""
__docformat__ = "reStructuredText"
def test_weakrefs_functional():
"""Persistent weak references
Persistent weak references are used much like Python weak
references. The major difference is that you can't specify an
object to be called when the object is removed from the database.
Here's an example. We'll start by creating a persistent object and
a reference to it:
>>> from persistent.wref import WeakRef
>>> import persistent, ZODB.tests.MinPO
>>> import ZODB.tests.util
>>> ob = ZODB.tests.MinPO.MinPO()
>>> ref = WeakRef(ob)
>>> ref() is ob
True
The hash of the ref if the same as the hash of the referenced object:
>>> hash(ref) == hash(ob)
True
Two refs to the same object are equal:
>>> WeakRef(ob) == ref
True
>>> ob2 = ZODB.tests.MinPO.MinPO(1)
>>> WeakRef(ob2) == ref
False
Lets save the reference and the referenced object in a database:
>>> db = ZODB.tests.util.DB()
>>> conn1 = db.open()
>>> conn1.root()['ob'] = ob
>>> conn1.root()['ref'] = ref
>>> transaction.commit()
If we open a new connection, we can use the reference:
>>> conn2 = db.open()
>>> conn2.root()['ref']() is conn2.root()['ob']
True
>>> hash(conn2.root()['ref']) == hash(conn2.root()['ob'])
True
But if we delete the referenced object and pack:
>>> del conn2.root()['ob']
>>> transaction.commit()
>>> ZODB.tests.util.pack(db)
And then look in a new connection:
>>> conn3 = db.open()
>>> conn3.root()['ob']
Traceback (most recent call last):
...
KeyError: 'ob'
Trying to dereference the reference returns None:
>>> conn3.root()['ref']()
Trying to get a hash, raises a type error:
>>> hash(conn3.root()['ref'])
Traceback (most recent call last):
...
TypeError: Weakly-referenced object has gone away
Always explicitly close databases: :)
>>> db.close()
>>> del ob, ref, db, conn1, conn2, conn3
When multiple databases are in use, a weakref in one database may
point to an object in a different database. Let's create two new
databases to demonstrate this.
>>> dbA = ZODB.tests.util.DB(
... database_name = 'dbA',
... )
>>> dbB = ZODB.tests.util.DB(
... database_name = 'dbB',
... databases = dbA.databases,
... )
>>> connA1 = dbA.open()
>>> connB1 = connA1.get_connection('dbB')
Now create and add a new object and a weak reference, and add them
to different databases.
>>> ob = ZODB.tests.MinPO.MinPO()
>>> ref = WeakRef(ob)
>>> connA1.root()['ob'] = ob
>>> connA1.add(ob)
>>> connB1.root()['ref'] = ref
>>> transaction.commit()
After a succesful commit, the reference should know the oid,
database name and connection of the object.
>>> ref.oid == ob._p_oid
True
>>> ref.database_name == 'dbA'
True
>>> ref.dm is ob._p_jar is connA1
True
If we open new connections, we should be able to use the reference.
>>> connA2 = dbA.open()
>>> connB2 = connA2.get_connection('dbB')
>>> ref2 = connB2.root()['ref']
>>> ob2 = connA2.root()['ob']
>>> ref2() is ob2
True
>>> ref2.oid == ob2._p_oid
True
>>> ref2.database_name == 'dbA'
True
>>> ref2.dm is ob2._p_jar is connA2
True
Always explicitly close databases: :)
>>> dbA.close()
>>> dbB.close()
"""
def test_PersistentWeakKeyDictionary():
"""Persistent weak key dictionary
This is akin to WeakKeyDictionaries. Note, however, that removal
of items is extremely lazy. See below.
We'll start by creating a PersistentWeakKeyDictionary and adding
some persistent objects to it.
>>> from persistent.wref import PersistentWeakKeyDictionary
>>> d = PersistentWeakKeyDictionary()
>>> import ZODB.tests.util
>>> p1 = ZODB.tests.util.P('p1')
>>> p2 = ZODB.tests.util.P('p2')
>>> p3 = ZODB.tests.util.P('p3')
>>> d[p1] = 1
>>> d[p2] = 2
>>> d[p3] = 3
We'll create an extra persistent object that's not in the dict:
>>> p4 = ZODB.tests.util.P('p4')
Now we'll excercise iteration and item access:
>>> l = [(str(k), d[k], d.get(k)) for k in d]
>>> l.sort()
>>> l
[('P(p1)', 1, 1), ('P(p2)', 2, 2), ('P(p3)', 3, 3)]
And the containment operator:
>>> [p in d for p in [p1, p2, p3, p4]]
[True, True, True, False]
We can add the dict and the referenced objects to a database:
>>> db = ZODB.tests.util.DB()
>>> conn1 = db.open()
>>> conn1.root()['p1'] = p1
>>> conn1.root()['d'] = d
>>> conn1.root()['p2'] = p2
>>> conn1.root()['p3'] = p3
>>> transaction.commit()
And things still work, as before:
>>> l = [(str(k), d[k], d.get(k)) for k in d]
>>> l.sort()
>>> l
[('P(p1)', 1, 1), ('P(p2)', 2, 2), ('P(p3)', 3, 3)]
>>> [p in d for p in [p1, p2, p3, p4]]
[True, True, True, False]
Likewise, we can read the objects from another connection and
things still work.
>>> conn2 = db.open()
>>> d = conn2.root()['d']
>>> p1 = conn2.root()['p1']
>>> p2 = conn2.root()['p2']
>>> p3 = conn2.root()['p3']
>>> l = [(str(k), d[k], d.get(k)) for k in d]
>>> l.sort()
>>> l
[('P(p1)', 1, 1), ('P(p2)', 2, 2), ('P(p3)', 3, 3)]
>>> [p in d for p in [p1, p2, p3, p4]]
[True, True, True, False]
Now, we'll delete one of the objects from the database, but *not*
from the dictionary:
>>> del conn2.root()['p2']
>>> transaction.commit()
And pack the database, so that the no-longer referenced p2 is
actually removed from the database.
>>> ZODB.tests.util.pack(db)
Now if we access the dictionary in a new connection, it no longer
has p2:
>>> conn3 = db.open()
>>> d = conn3.root()['d']
>>> l = [(str(k), d[k], d.get(k)) for k in d]
>>> l.sort()
>>> l
[('P(p1)', 1, 1), ('P(p3)', 3, 3)]
It's worth nothing that that the versions of the dictionary in
conn1 and conn2 still have p2, because p2 is still in the caches
for those connections.
Always explicitly close databases: :)
>>> db.close()
"""
def test_suite():
from doctest import DocTestSuite
return DocTestSuite()
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