Add a BinaryField model field

Thanks Michael Jung, Charl Botha and Florian Apolloner for review
and help on the patch.

tests/model_fields/tests.py

@@ -12,8 +12,8 @@ from django.utils import six
 from django.utils import unittest
 
 from .models import (Foo, Bar, Whiz, BigD, BigS, Image, BigInt, Post,
-    NullBooleanModel, BooleanModel, Document, RenamedField, VerboseNameField,
-    FksToBooleans)
+    NullBooleanModel, BooleanModel, DataModel, Document, RenamedField,
+    VerboseNameField, FksToBooleans)
 
 from .imagefield import (ImageFieldTests, ImageFieldTwoDimensionsTests,
     TwoImageFieldTests, ImageFieldNoDimensionsTests,
@@ -424,3 +424,25 @@ class FileFieldTests(unittest.TestCase):
         field = d._meta.get_field('myfile')
         field.save_form_data(d, 'else.txt')
         self.assertEqual(d.myfile, 'else.txt')
+
+
+class BinaryFieldTests(test.TestCase):
+    binary_data = b'\x00\x46\xFE'
+
+    def test_set_and_retrieve(self):
+        data_set = (self.binary_data, six.memoryview(self.binary_data))
+        for bdata in data_set:
+            dm = DataModel(data=bdata)
+            dm.save()
+            dm = DataModel.objects.get(pk=dm.pk)
+            self.assertEqual(bytes(dm.data), bytes(bdata))
+            # Resave (=update)
+            dm.save()
+            dm = DataModel.objects.get(pk=dm.pk)
+            self.assertEqual(bytes(dm.data), bytes(bdata))
+            # Test default value
+            self.assertEqual(bytes(dm.short_data), b'\x08')
+
+    def test_max_length(self):
+        dm = DataModel(short_data=self.binary_data*4)
+        self.assertRaises(ValidationError, dm.full_clean)