Fixed #24215 -- Refactored lazy model operations

This adds a new method, Apps.lazy_model_operation(), and a helper function,
lazy_related_operation(), which together supersede add_lazy_relation() and
make lazy model operations the responsibility of the App registry. This
system no longer uses the class_prepared signal.

10 files changed, 234 insertions, 168 deletions

diff --git a/django/apps/registry.py b/django/apps/registry.py
index 164427d85f..96d4db5f17 100644
--- a/django/apps/registry.py
+++ b/django/apps/registry.py
@@ -2,6 +2,7 @@ import sys
 import threading
 import warnings
 from collections import Counter, OrderedDict, defaultdict
+from functools import partial
 
 from django.core.exceptions import AppRegistryNotReady, ImproperlyConfigured
 from django.utils import lru_cache
@@ -45,8 +46,10 @@ class Apps(object):
         # Lock for thread-safe population.
         self._lock = threading.Lock()
 
-        # Pending lookups for lazy relations.
-        self._pending_lookups = {}
+        # Maps ("app_label", "modelname") tuples to lists of functions to be
+        # called when the corresponding model is ready. Used by this class's
+        # `lazy_model_operation()` and `do_pending_operations()` methods.
+        self._pending_operations = defaultdict(list)
 
         # Populate apps and models, unless it's the master registry.
         if installed_apps is not None:
@@ -207,6 +210,7 @@ class Apps(object):
                     "Conflicting '%s' models in application '%s': %s and %s." %
                     (model_name, app_label, app_models[model_name], model))
         app_models[model_name] = model
+        self.do_pending_operations(model)
         self.clear_cache()
 
     def is_installed(self, app_name):
@@ -332,5 +336,42 @@ class Apps(object):
                 for model in app_config.get_models(include_auto_created=True):
                     model._meta._expire_cache()
 
+    def lazy_model_operation(self, function, *model_keys):
+        """
+        Take a function and a number of ("app_label", "modelname") tuples, and
+        when all the corresponding models have been imported and registered,
+        call the function with the model classes as its arguments.
+
+        The function passed to this method must accept exactly n models as
+        arguments, where n=len(model_keys).
+        """
+        # If this function depends on more than one model, we recursively turn
+        # it into a chain of functions that accept a single model argument and
+        # pass each in turn to lazy_model_operation.
+        model_key, more_models = model_keys[0], model_keys[1:]
+        if more_models:
+            supplied_fn = function
+
+            def function(model):
+                next_function = partial(supplied_fn, model)
+                self.lazy_model_operation(next_function, *more_models)
+
+        # If the model is already loaded, pass it to the function immediately.
+        # Otherwise, delay execution until the class is prepared.
+        try:
+            model_class = self.get_registered_model(*model_key)
+        except LookupError:
+            self._pending_operations[model_key].append(function)
+        else:
+            function(model_class)
+
+    def do_pending_operations(self, model):
+        """
+        Take a newly-prepared model and pass it to each function waiting for
+        it. This is called at the very end of `Apps.register_model()`.
+        """
+        key = model._meta.app_label, model._meta.model_name
+        for function in self._pending_operations.pop(key, []):
+            function(model)
 
 apps = Apps(installed_apps=None)
diff --git a/django/db/migrations/state.py b/django/db/migrations/state.py
index d0d065af8a..0482a680da 100644
--- a/django/db/migrations/state.py
+++ b/django/db/migrations/state.py
@@ -8,10 +8,9 @@ from django.apps.registry import Apps, apps as global_apps
 from django.conf import settings
 from django.db import models
 from django.db.models.fields.proxy import OrderWrt
-from django.db.models.fields.related import (
-    RECURSIVE_RELATIONSHIP_CONSTANT, do_pending_lookups,
-)
+from django.db.models.fields.related import RECURSIVE_RELATIONSHIP_CONSTANT
 from django.db.models.options import DEFAULT_NAMES, normalize_together
+from django.db.models.utils import make_model_tuple
 from django.utils import six
 from django.utils.encoding import force_text, smart_text
 from django.utils.functional import cached_property
@@ -214,22 +213,21 @@ class StateApps(Apps):
         self.render_multiple(list(models.values()) + self.real_models)
 
         # If there are some lookups left, see if we can first resolve them
-        # ourselves - sometimes fields are added after class_prepared is sent
-        for lookup_model, operations in self._pending_lookups.items():
+        # ourselves - sometimes fields are added after a model is registered
+        for lookup_model in self._pending_operations:
             try:
-                model = self.get_model(lookup_model[0], lookup_model[1])
+                model = self.get_model(*lookup_model)
             except LookupError:
-                app_label = "%s.%s" % (lookup_model[0], lookup_model[1])
-                if app_label == settings.AUTH_USER_MODEL and ignore_swappable:
+                if lookup_model == make_model_tuple(settings.AUTH_USER_MODEL) and ignore_swappable:
                     continue
                 # Raise an error with a best-effort helpful message
                 # (only for the first issue). Error message should look like:
                 # "ValueError: Lookup failed for model referenced by
                 # field migrations.Book.author: migrations.Author"
-                msg = "Lookup failed for model referenced by field {field}: {model[0]}.{model[1]}"
-                raise ValueError(msg.format(field=operations[0][1], model=lookup_model))
+                msg = "Lookup failed for model: {model[0]}.{model[1]}"
+                raise ValueError(msg.format(model=lookup_model))
             else:
-                do_pending_lookups(model)
+                self.do_pending_operations(model)
 
     def render_multiple(self, model_states):
         # We keep trying to render the models in a loop, ignoring invalid
@@ -277,6 +275,7 @@ class StateApps(Apps):
             self.app_configs[app_label] = AppConfigStub(app_label)
             self.app_configs[app_label].models = OrderedDict()
         self.app_configs[app_label].models[model._meta.model_name] = model
+        self.do_pending_operations(model)
         self.clear_cache()
 
     def unregister_model(self, app_label, model_name):
diff --git a/django/db/models/base.py b/django/db/models/base.py
index fdd1ce28d9..b5d140393f 100644
--- a/django/db/models/base.py
+++ b/django/db/models/base.py
@@ -21,7 +21,8 @@ from django.db.models.constants import LOOKUP_SEP
 from django.db.models.deletion import Collector
 from django.db.models.fields import AutoField
 from django.db.models.fields.related import (
-    ForeignObjectRel, ManyToOneRel, OneToOneField, add_lazy_relation,
+    ForeignObjectRel, ManyToOneRel, OneToOneField, lazy_related_operation,
+    resolve_relation,
 )
 from django.db.models.manager import ensure_default_manager
 from django.db.models.options import Options
@@ -29,6 +30,7 @@ from django.db.models.query import Q
 from django.db.models.query_utils import (
     DeferredAttribute, deferred_class_factory,
 )
+from django.db.models.utils import make_model_tuple
 from django.utils import six
 from django.utils.encoding import force_str, force_text
 from django.utils.functional import curry
@@ -199,8 +201,8 @@ class ModelBase(type):
             # Locate OneToOneField instances.
             for field in base._meta.local_fields:
                 if isinstance(field, OneToOneField):
-                    parent_links[field.remote_field.model] = field
-
+                    related = resolve_relation(new_class, field.remote_field.model)
+                    parent_links[make_model_tuple(related)] = field
         # Do the appropriate setup for any model parents.
         for base in parents:
             original_base = base
@@ -223,8 +225,9 @@ class ModelBase(type):
             if not base._meta.abstract:
                 # Concrete classes...
                 base = base._meta.concrete_model
-                if base in parent_links:
-                    field = parent_links[base]
+                base_key = make_model_tuple(base)
+                if base_key in parent_links:
+                    field = parent_links[base_key]
                 elif not is_proxy:
                     attr_name = '%s_ptr' % base._meta.model_name
                     field = OneToOneField(base, name=attr_name,
@@ -305,7 +308,7 @@ class ModelBase(type):
 
             # defer creating accessors on the foreign class until we are
             # certain it has been created
-            def make_foreign_order_accessors(field, model, cls):
+            def make_foreign_order_accessors(cls, model, field):
                 setattr(
                     field.remote_field.model,
                     'get_%s_order' % cls.__name__.lower(),
@@ -316,12 +319,8 @@ class ModelBase(type):
                     'set_%s_order' % cls.__name__.lower(),
                     curry(method_set_order, cls)
                 )
-            add_lazy_relation(
-                cls,
-                opts.order_with_respect_to,
-                opts.order_with_respect_to.remote_field.model,
-                make_foreign_order_accessors
-            )
+            wrt = opts.order_with_respect_to
+            lazy_related_operation(make_foreign_order_accessors, cls, wrt.remote_field.model, field=wrt)
 
         # Give the class a docstring -- its definition.
         if cls.__doc__ is None:
diff --git a/django/db/models/fields/related.py b/django/db/models/fields/related.py
index 9e6bbaaf29..cd535f2c4e 100644
--- a/django/db/models/fields/related.py
+++ b/django/db/models/fields/related.py
@@ -1,6 +1,7 @@
 from __future__ import unicode_literals
 
 import warnings
+from functools import partial
 from operator import attrgetter
 
 from django import forms
@@ -21,6 +22,7 @@ from django.db.models.fields.related_lookups import (
 )
 from django.db.models.query import QuerySet
 from django.db.models.query_utils import PathInfo
+from django.db.models.utils import make_model_tuple
 from django.utils import six
 from django.utils.deprecation import (
     RemovedInDjango20Warning, RemovedInDjango21Warning,
@@ -32,75 +34,60 @@ from django.utils.translation import ugettext_lazy as _
 RECURSIVE_RELATIONSHIP_CONSTANT = 'self'
 
 
-def add_lazy_relation(cls, field, relation, operation):
+def resolve_relation(scope_model, relation):
     """
-    Adds a lookup on ``cls`` when a related field is defined using a string,
-    i.e.::
-
-        class MyModel(Model):
-            fk = ForeignKey("AnotherModel")
-
-    This string can be:
-
-        * RECURSIVE_RELATIONSHIP_CONSTANT (i.e. "self") to indicate a recursive
-          relation.
-
-        * The name of a model (i.e "AnotherModel") to indicate another model in
-          the same app.
-
-        * An app-label and model name (i.e. "someapp.AnotherModel") to indicate
-          another model in a different app.
-
-    If the other model hasn't yet been loaded -- almost a given if you're using
-    lazy relationships -- then the relation won't be set up until the
-    class_prepared signal fires at the end of model initialization.
-
-    ``operation`` is the work that must be performed once the relation can be
-    resolved.
+    Transform relation into a model or fully-qualified model string of the form
+    "app_label.ModelName", relative to scope_model.
+
+    The relation argument can be:
+      * RECURSIVE_RELATIONSHIP_CONSTANT, i.e. the string "self", in which case
+        the model argument will be returned.
+      * A bare model name without an app_label, in which case scope_model's
+        app_label will be prepended.
+      * An "app_label.ModelName" string.
+      * A model class, which will be returned unchanged.
     """
     # Check for recursive relations
     if relation == RECURSIVE_RELATIONSHIP_CONSTANT:
-        app_label = cls._meta.app_label
-        model_name = cls.__name__
+        relation = scope_model
 
-    else:
-        # Look for an "app.Model" relation.
+    # Look for an "app.Model" relation
+    if isinstance(relation, six.string_types):
+        if "." not in relation:
+            relation = "%s.%s" % (scope_model._meta.app_label, relation)
 
-        if isinstance(relation, six.string_types):
-            try:
-                app_label, model_name = relation.split(".")
-            except ValueError:
-                # If we can't split, assume a model in current app.
-                app_label = cls._meta.app_label
-                model_name = relation
-        else:
-            # It's actually a model class.
-            app_label = relation._meta.app_label
-            model_name = relation._meta.object_name
-
-    # Try to look up the related model, and if it's already loaded resolve the
-    # string right away. If get_registered_model raises a LookupError, it means
-    # that the related model isn't loaded yet, so we need to pend the relation
-    # until the class is prepared.
-    try:
-        model = cls._meta.apps.get_registered_model(app_label, model_name)
-    except LookupError:
-        key = (app_label, model_name)
-        value = (cls, field, operation)
-        cls._meta.apps._pending_lookups.setdefault(key, []).append(value)
-    else:
-        operation(field, model, cls)
-
-
-def do_pending_lookups(sender, **kwargs):
+    return relation
+
+
+def lazy_related_operation(function, model, *related_models, **kwargs):
     """
-    Sent from class_prepared to handle pending relations to the sending model.
+    Schedule `function` to be called once `model` and all `related_models`
+    have been imported and registered with the app registry. `function` will
+    be called with the newly-loaded model classes as its positional arguments,
+    plus any optional keyword arguments.
+
+    The `model` argument must be a model class. Each subsequent positional
+    argument is another model, or a reference to another model - see
+    `resolve_relation()` for the various forms these may take. Any relative
+    references will be resolved relative to `model`.
+
+    This is a convenience wrapper for `Apps.lazy_model_operation` - the app
+    registry model used is the one found in `model._meta.apps`.
     """
-    key = (sender._meta.app_label, sender.__name__)
-    for cls, field, operation in sender._meta.apps._pending_lookups.pop(key, []):
-        operation(field, sender, cls)
+    models = [model] + [resolve_relation(model, rel) for rel in related_models]
+    model_keys = (make_model_tuple(m) for m in models)
+    apps = model._meta.apps
+    return apps.lazy_model_operation(partial(function, **kwargs), *model_keys)
 
-signals.class_prepared.connect(do_pending_lookups)
+
+def add_lazy_relation(cls, field, relation, operation):
+    warnings.warn(
+        "add_lazy_relation() has been superseded by lazy_related_operation() "
+        "and related methods on the Apps class.",
+        RemovedInDjango21Warning, stacklevel=2)
+    # Rearrange args for new Apps.lazy_model_operation
+    function = lambda local, related, field: operation(field, related, local)
+    lazy_related_operation(function, cls, relation, field=field)
 
 
 class RelatedField(Field):
@@ -289,12 +276,10 @@ class RelatedField(Field):
         return None
 
     def contribute_to_class(self, cls, name, virtual_only=False):
-        sup = super(RelatedField, self)
 
-        self.opts = cls._meta
+        super(RelatedField, self).contribute_to_class(cls, name, virtual_only=virtual_only)
 
-        if hasattr(sup, 'contribute_to_class'):
-            sup.contribute_to_class(cls, name, virtual_only=virtual_only)
+        self.opts = cls._meta
 
         if not cls._meta.abstract:
             if self.remote_field.related_name:
@@ -303,14 +288,11 @@ class RelatedField(Field):
                     'app_label': cls._meta.app_label.lower()
                 }
                 self.remote_field.related_name = related_name
-            other = self.remote_field.model
-            if isinstance(other, six.string_types) or other._meta.pk is None:
-                def resolve_related_class(field, model, cls):
-                    field.remote_field.model = model
-                    field.do_related_class(model, cls)
-                add_lazy_relation(cls, self, other, resolve_related_class)
-            else:
-                self.do_related_class(other, cls)
+
+            def resolve_related_class(model, related, field):
+                field.remote_field.model = related
+                field.do_related_class(related, model)
+            lazy_related_operation(resolve_related_class, cls, self.remote_field.model, field=self)
 
     @property
     def swappable_setting(self):
@@ -351,8 +333,7 @@ class RelatedField(Field):
 
     def do_related_class(self, other, cls):
         self.set_attributes_from_rel()
-        if not cls._meta.abstract:
-            self.contribute_to_related_class(other, self.remote_field)
+        self.contribute_to_related_class(other, self.remote_field)
 
     def get_limit_choices_to(self):
         """
@@ -2132,32 +2113,22 @@ class OneToOneField(ForeignKey):
 
 def create_many_to_many_intermediary_model(field, klass):
     from django.db import models
-    managed = True
-    if isinstance(field.remote_field.model, six.string_types) and field.remote_field.model != RECURSIVE_RELATIONSHIP_CONSTANT:
-        to_model = field.remote_field.model
-        to = to_model.split('.')[-1]
-
-        def set_managed(field, model, cls):
-            field.remote_field.through._meta.managed = model._meta.managed or cls._meta.managed
-        add_lazy_relation(klass, field, to_model, set_managed)
-    elif isinstance(field.remote_field.model, six.string_types):
-        to = klass._meta.object_name
-        to_model = klass
-        managed = klass._meta.managed
-    else:
-        to = field.remote_field.model._meta.object_name
-        to_model = field.remote_field.model
-        managed = klass._meta.managed or to_model._meta.managed
+
+    def set_managed(model, related, through):
+        through._meta.managed = model._meta.managed or related._meta.managed
+
+    to_model = resolve_relation(klass, field.remote_field.model)
     name = '%s_%s' % (klass._meta.object_name, field.name)
-    if field.remote_field.model == RECURSIVE_RELATIONSHIP_CONSTANT or to == klass._meta.object_name:
-        from_ = 'from_%s' % to.lower()
-        to = 'to_%s' % to.lower()
-    else:
-        from_ = klass._meta.model_name
-        to = to.lower()
+    lazy_related_operation(set_managed, klass, to_model, name)
+
+    to = make_model_tuple(to_model)[1]
+    from_ = klass._meta.model_name
+    if to == from_:
+        to = 'to_%s' % to
+        from_ = 'from_%s' % from_
+
     meta = type(str('Meta'), (object,), {
         'db_table': field._get_m2m_db_table(klass._meta),
-        'managed': managed,
         'auto_created': klass,
         'app_label': klass._meta.app_label,
         'db_tablespace': klass._meta.db_tablespace,
@@ -2323,7 +2294,7 @@ class ManyToManyField(RelatedField):
             )
 
             # Set some useful local variables
-            to_model = self.remote_field.model
+            to_model = resolve_relation(from_model, self.remote_field.model)
             from_model_name = from_model._meta.object_name
             if isinstance(to_model, six.string_types):
                 to_model_name = to_model
@@ -2657,8 +2628,13 @@ class ManyToManyField(RelatedField):
         #  1) There is a manually specified intermediate, or
         #  2) The class owning the m2m field is abstract.
         #  3) The class owning the m2m field has been swapped out.
-        if not self.remote_field.through and not cls._meta.abstract and not cls._meta.swapped:
-            self.remote_field.through = create_many_to_many_intermediary_model(self, cls)
+        if not cls._meta.abstract:
+            if self.remote_field.through:
+                def resolve_through_model(_, model, field):
+                    field.remote_field.through = model
+                lazy_related_operation(resolve_through_model, cls, self.remote_field.through, field=self)
+            elif not cls._meta.swapped:
+                self.remote_field.through = create_many_to_many_intermediary_model(self, cls)
 
         # Add the descriptor for the m2m relation.
         setattr(cls, self.name, ManyRelatedObjectsDescriptor(self.remote_field, reverse=False))
@@ -2666,13 +2642,6 @@ class ManyToManyField(RelatedField):
         # Set up the accessor for the m2m table name for the relation.
         self.m2m_db_table = curry(self._get_m2m_db_table, cls._meta)
 
-        # Populate some necessary rel arguments so that cross-app relations
-        # work correctly.
-        if not cls._meta.abstract and isinstance(self.remote_field.through, six.string_types):
-            def resolve_through_model(field, model, cls):
-                field.remote_field.through = model
-            add_lazy_relation(cls, self, self.remote_field.through, resolve_through_model)
-
     def contribute_to_related_class(self, cls, related):
         # Internal M2Ms (i.e., those with a related name ending with '+')
         # and swapped models don't get a related descriptor.
diff --git a/django/db/models/utils.py b/django/db/models/utils.py
new file mode 100644
index 0000000000..f696e30ce2
--- /dev/null
+++ b/django/db/models/utils.py
@@ -0,0 +1,18 @@
+from django.utils import six
+
+
+def make_model_tuple(model):
+    """
+    Takes a model or a string of the form "app_label.ModelName" and returns a
+    corresponding ("app_label", "modelname") tuple. If a tuple is passed in,
+    it's assumed to be a valid model tuple already and returned unchanged.
+    """
+    if isinstance(model, tuple):
+        model_tuple = model
+    elif isinstance(model, six.string_types):
+        app_label, model_name = model.split(".")
+        model_tuple = app_label, model_name.lower()
+    else:
+        model_tuple = model._meta.app_label, model._meta.model_name
+    assert len(model_tuple) == 2, "Invalid model representation: %s" % model
+    return model_tuple
diff --git a/docs/internals/deprecation.txt b/docs/internals/deprecation.txt
index abce521d75..494f482828 100644
--- a/docs/internals/deprecation.txt
+++ b/docs/internals/deprecation.txt
@@ -30,6 +30,8 @@ details on these changes.
 
 * ``Field.remote_field.to`` attribute will be removed.
 
+* ``django.db.models.fields.add_lazy_relation`` will be removed.
+
 .. _deprecation-removed-in-2.0:
 
 2.0
diff --git a/docs/releases/1.9.txt b/docs/releases/1.9.txt
index 9f15e9151a..3626cd0a40 100644
--- a/docs/releases/1.9.txt
+++ b/docs/releases/1.9.txt
@@ -372,6 +372,8 @@ Miscellaneous
   :class:`~django.forms.SelectDateWidget` in ``django.forms.widgets``
   (or simply ``django.forms``) instead.
 
+* Private API ``django.db.models.fields.add_lazy_relation()`` is deprecated.
+
 .. removed-features-1.9:
 
 Features removed in 1.9
diff --git a/tests/apps/tests.py b/tests/apps/tests.py
index 89e295ffde..347996454f 100644
--- a/tests/apps/tests.py
+++ b/tests/apps/tests.py
@@ -259,6 +259,44 @@ class AppsTests(TestCase):
         finally:
             apps.apps_ready = True
 
+    def test_lazy_model_operation(self):
+        """
+        Tests apps.lazy_model_operation().
+        """
+        model_classes = []
+        initial_pending = set(apps._pending_operations)
+
+        def test_func(*models):
+            model_classes[:] = models
+
+        class LazyA(models.Model):
+            pass
+
+        # Test models appearing twice, and models appearing consecutively
+        model_keys = [('apps', model_name) for model_name in ['lazya', 'lazyb', 'lazyb', 'lazyc', 'lazya']]
+        apps.lazy_model_operation(test_func, *model_keys)
+
+        # LazyModelA shouldn't be waited on since it's already registered,
+        # and LazyModelC shouldn't be waited on until LazyModelB exists.
+        self.assertSetEqual(set(apps._pending_operations) - initial_pending, {('apps', 'lazyb')})
+
+        # Test that multiple operations can wait on the same model
+        apps.lazy_model_operation(test_func, ('apps', 'lazyb'))
+
+        class LazyB(models.Model):
+            pass
+
+        self.assertListEqual(model_classes, [LazyB])
+
+        # Now we are just waiting on LazyModelC.
+        self.assertSetEqual(set(apps._pending_operations) - initial_pending, {('apps', 'lazyc')})
+
+        class LazyC(models.Model):
+            pass
+
+        # Everything should be loaded - make sure the callback was executed properly.
+        self.assertListEqual(model_classes, [LazyA, LazyB, LazyB, LazyC, LazyA])
+
 
 class Stub(object):
     def __init__(self, **kwargs):
diff --git a/tests/model_fields/models.py b/tests/model_fields/models.py
index 4208454b68..cca2b463a0 100644
--- a/tests/model_fields/models.py
+++ b/tests/model_fields/models.py
@@ -373,14 +373,3 @@ class PrimaryKeyUUIDModel(models.Model):
 
 class RelatedToUUIDModel(models.Model):
     uuid_fk = models.ForeignKey('PrimaryKeyUUIDModel')
-
-
-###############################################################################
-
-# See ticket #24215.
-class AbstractForeignFieldsModel(models.Model):
-    fk = models.ForeignKey('missing.FK')
-    m2m = models.ManyToManyField('missing.M2M', through='missing.Through')
-
-    class Meta:
-        abstract = True
diff --git a/tests/model_fields/tests.py b/tests/model_fields/tests.py
index 31f2cee337..6b63b8f115 100644
--- a/tests/model_fields/tests.py
+++ b/tests/model_fields/tests.py
@@ -5,6 +5,7 @@ import unittest
 from decimal import Decimal
 
 from django import forms, test
+from django.apps import apps
 from django.core import checks, validators
 from django.core.exceptions import ValidationError
 from django.db import IntegrityError, connection, models, transaction
@@ -21,12 +22,11 @@ from django.utils import six
 from django.utils.functional import lazy
 
 from .models import (
-    AbstractForeignFieldsModel, Bar, BigD, BigIntegerModel, BigS, BooleanModel,
-    DataModel, DateTimeModel, Document, FksToBooleans, FkToChar, FloatModel,
-    Foo, GenericIPAddress, IntegerModel, NullBooleanModel,
-    PositiveIntegerModel, PositiveSmallIntegerModel, Post, PrimaryKeyCharModel,
-    RenamedField, SmallIntegerModel, VerboseNameField, Whiz, WhizIter,
-    WhizIterEmpty,
+    Bar, BigD, BigIntegerModel, BigS, BooleanModel, DataModel, DateTimeModel,
+    Document, FksToBooleans, FkToChar, FloatModel, Foo, GenericIPAddress,
+    IntegerModel, NullBooleanModel, PositiveIntegerModel,
+    PositiveSmallIntegerModel, Post, PrimaryKeyCharModel, RenamedField,
+    SmallIntegerModel, VerboseNameField, Whiz, WhizIter, WhizIterEmpty,
 )
 
 
@@ -202,37 +202,46 @@ class ForeignKeyTests(test.TestCase):
         rel_name = Bar._meta.get_field('a').remote_field.related_name
         self.assertIsInstance(rel_name, six.text_type)
 
-    def test_abstract_model_pending_lookups(self):
+    def test_abstract_model_pending_operations(self):
         """
         Foreign key fields declared on abstract models should not add lazy relations to
         resolve relationship declared as string. refs #24215
         """
-        opts = AbstractForeignFieldsModel._meta
-        to_key = ('missing', 'FK')
-        fk_lookup = (AbstractForeignFieldsModel, opts.get_field('fk'))
-        self.assertFalse(
-            any(lookup[0:2] == fk_lookup for lookup in opts.apps._pending_lookups.get(to_key, [])),
-            'Pending lookup added for the abstract model foreign key `to` parameter'
+        pending_ops_before = list(apps._pending_operations.items())
+
+        class AbstractForeignKeyModel(models.Model):
+            fk = models.ForeignKey('missing.FK')
+
+            class Meta:
+                abstract = True
+
+        self.assertIs(AbstractForeignKeyModel._meta.apps, apps)
+        self.assertEqual(
+            pending_ops_before,
+            list(apps._pending_operations.items()),
+            "Pending lookup added for a foreign key on an abstract model"
         )
 
 
 class ManyToManyFieldTests(test.TestCase):
-    def test_abstract_model_pending_lookups(self):
+    def test_abstract_model_pending_operations(self):
         """
         Many-to-many fields declared on abstract models should not add lazy relations to
         resolve relationship declared as string. refs #24215
         """
-        opts = AbstractForeignFieldsModel._meta
-        to_key = ('missing', 'M2M')
-        fk_lookup = (AbstractForeignFieldsModel, opts.get_field('m2m'))
-        self.assertFalse(
-            any(lookup[0:2] == fk_lookup for lookup in opts.apps._pending_lookups.get(to_key, [])),
-            'Pending lookup added for the abstract model many-to-many `to` parameter.'
-        )
-        through_key = ('missing', 'Through')
-        self.assertFalse(
-            any(lookup[0:2] == fk_lookup for lookup in opts.apps._pending_lookups.get(through_key, [])),
-            'Pending lookup added for the abstract model many-to-many `through` parameter.'
+        pending_ops_before = list(apps._pending_operations.items())
+
+        class AbstractManyToManyModel(models.Model):
+            fk = models.ForeignKey('missing.FK')
+
+            class Meta:
+                abstract = True
+
+        self.assertIs(AbstractManyToManyModel._meta.apps, apps)
+        self.assertEqual(
+            pending_ops_before,
+            list(apps._pending_operations.items()),
+            "Pending lookup added for a many-to-many field on an abstract model"
         )