magic-removal: Moved model unit tests from 'testapp' package into 'modeltests' package, with each model test getting its own app

git-svn-id: http://code.djangoproject.com/svn/django/branches/magic-removal@1606 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/modeltests/many_to_one_null/models.py

@@ -0,0 +1,78 @@
+"""
+16. Many-to-one relationships that can be null
+
+To define a many-to-one relationship that can have a null foreign key, use
+``ForeignKey()`` with ``null=True`` .
+"""
+
+from django.core import meta
+
+class Reporter(meta.Model):
+    name = meta.CharField(maxlength=30)
+
+    def __repr__(self):
+        return self.name
+
+class Article(meta.Model):
+    headline = meta.CharField(maxlength=100)
+    reporter = meta.ForeignKey(Reporter, null=True)
+
+    def __repr__(self):
+        return self.headline
+
+API_TESTS = """
+# Create a Reporter.
+>>> r = Reporter(name='John Smith')
+>>> r.save()
+
+# Create an Article.
+>>> a = Article(headline="First", reporter=r)
+>>> a.save()
+
+>>> a.reporter_id
+1
+
+>>> a.get_reporter()
+John Smith
+
+# Article objects have access to their related Reporter objects.
+>>> r = a.get_reporter()
+
+# Create an Article via the Reporter object.
+>>> a2 = r.add_article(headline="Second")
+>>> a2
+Second
+>>> a2.reporter_id
+1
+
+# Reporter objects have access to their related Article objects.
+>>> r.get_article_list(order_by=['headline'])
+[First, Second]
+>>> r.get_article(headline__startswith='Fir')
+First
+>>> r.get_article_count()
+2
+
+# Create an Article with no Reporter by passing "reporter=None".
+>>> a3 = Article(headline="Third", reporter=None)
+>>> a3.save()
+>>> a3.id
+3
+>>> a3.reporter_id
+>>> print a3.reporter_id
+None
+>>> a3 = Article.objects.get_object(pk=3)
+>>> print a3.reporter_id
+None
+
+# An article's get_reporter() method throws ReporterDoesNotExist
+# if the reporter is set to None.
+>>> a3.get_reporter()
+Traceback (most recent call last):
+    ...
+DoesNotExist
+
+# To retrieve the articles with no reporters set, use "reporter__isnull=True".
+>>> Article.objects.get_list(reporter__isnull=True)
+[Third]
+"""