3 files changed, 95 insertions, 0 deletions
diff --git a/tests/modeltests/defer/__init__.py b/tests/modeltests/defer/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/tests/modeltests/defer/__init__.py
diff --git a/tests/modeltests/defer/models.py b/tests/modeltests/defer/models.py
new file mode 100644
index 0000000000..1f515bc95e
--- /dev/null
+++ b/tests/modeltests/defer/models.py
@@ -0,0 +1,89 @@
+"""
+Tests for defer() and only().
+"""
+
+from django.db import models
+from django.db.models.query_utils import DeferredAttribute
+
+class Secondary(models.Model):
+    first = models.CharField(max_length=50)
+    second = models.CharField(max_length=50)
+
+class Primary(models.Model):
+    name = models.CharField(max_length=50)
+    value = models.CharField(max_length=50)
+    related = models.ForeignKey(Secondary)
+
+def count_delayed_fields(obj, debug=False):
+    """
+    Returns the number of delayed attributes on the given model instance.
+    """
+    count = 0
+    for field in obj._meta.fields:
+        if isinstance(obj.__class__.__dict__.get(field.attname),
+                DeferredAttribute):
+            if debug:
+                print field.name, field.attname
+            count += 1
+    return count
+
+
+__test__ = {"API_TEST": """
+To all outward appearances, instances with deferred fields look the same as
+normal instances when we examine attribut values. Therefore we test for the
+number of deferred fields on returned instances (by poking at the internals),
+as a way to observe what is going on.
+
+>>> s1 = Secondary.objects.create(first="x1", second="y1")
+>>> p1 = Primary.objects.create(name="p1", value="xx", related=s1)
+
+>>> qs = Primary.objects.all()
+
+>>> count_delayed_fields(qs.defer('name')[0])
+1
+>>> count_delayed_fields(qs.only('name')[0])
+2
+>>> count_delayed_fields(qs.defer('related__first')[0])
+0
+>>> obj = qs.select_related().only('related__first')[0]
+>>> count_delayed_fields(obj)
+2
+>>> obj.related_id == s1.pk
+True
+>>> count_delayed_fields(qs.defer('name').extra(select={'a': 1})[0])
+1
+>>> count_delayed_fields(qs.extra(select={'a': 1}).defer('name')[0])
+1
+>>> count_delayed_fields(qs.defer('name').defer('value')[0])
+2
+>>> count_delayed_fields(qs.only('name').only('value')[0])
+2
+>>> count_delayed_fields(qs.only('name').defer('value')[0])
+2
+>>> count_delayed_fields(qs.only('name', 'value').defer('value')[0])
+2
+>>> count_delayed_fields(qs.defer('name').only('value')[0])
+2
+>>> obj = qs.only()[0]
+>>> count_delayed_fields(qs.defer(None)[0])
+0
+>>> count_delayed_fields(qs.only('name').defer(None)[0])
+0
+
+User values() won't defer anything (you get the full list of dictionaries
+back), but it still works.
+>>> qs.defer('name').values()[0] == {'id': p1.id, 'name': u'p1', 'value': 'xx', 'related_id': s1.id}
+True
+>>> qs.only('name').values()[0] == {'id': p1.id, 'name': u'p1', 'value': 'xx', 'related_id': s1.id}
+True
+
+Using defer() and only() with get() is also valid.
+>>> count_delayed_fields(qs.defer('name').get(pk=p1.pk))
+1
+>>> count_delayed_fields(qs.only('name').get(pk=p1.pk))
+2
+
+# KNOWN NOT TO WORK: >>> count_delayed_fields(qs.only('name').select_related('related')[0])
+# KNOWN NOT TO WORK >>> count_delayed_fields(qs.defer('related').select_related('related')[0])
+
+"""}
diff --git a/tests/regressiontests/queries/models.py b/tests/regressiontests/queries/models.py
index ccf06be5f3..939fc0e86f 100644
--- a/tests/regressiontests/queries/models.py
+++ b/tests/regressiontests/queries/models.py
@@ -890,6 +890,12 @@ unpickling.
 >>> query2.as_sql()[0] == query
 True
 
+Check pickling of deferred-loading querysets
+>>> qs = Item.objects.defer('name', 'creator')
+>>> q2 = pickle.loads(pickle.dumps(qs))
+>>> list(qs) == list(q2)
+True
+
 Bug #7277
 >>> n1.annotation_set.filter(Q(tag=t5) | Q(tag__children=t5) | Q(tag__children__children=t5))
 [<Annotation: a1>]