Made an expressions_case test work without Pillow.

tests/expressions_case/models.py

@@ -3,6 +3,11 @@ from __future__ import unicode_literals
 from django.db import models
 from django.utils.encoding import python_2_unicode_compatible
 
+try:
+    from PIL import Image
+except ImportError:
+    Image = None
+
 
 @python_2_unicode_compatible
 class CaseTestModel(models.Model):
@@ -22,7 +27,8 @@ class CaseTestModel(models.Model):
     file = models.FileField(null=True, db_column='file_field')
     file_path = models.FilePathField(null=True)
     float = models.FloatField(null=True, db_column='float_field')
-    image = models.ImageField(null=True)
+    if Image:
+        image = models.ImageField(null=True)
     ip_address = models.IPAddressField(null=True)
     generic_ip_address = models.GenericIPAddressField(null=True)
     null_boolean = models.NullBooleanField()

tests/expressions_case/tests.py

@@ -3,6 +3,7 @@ from __future__ import unicode_literals
 from datetime import date, datetime, time, timedelta
 from decimal import Decimal
 from operator import attrgetter, itemgetter
+import unittest
 from uuid import UUID
 
 from django.core.exceptions import FieldError
@@ -12,6 +13,11 @@ from django.db.models.expressions import Case, When
 from django.test import TestCase
 from django.utils import six
 
+try:
+    from PIL import Image
+except ImportError:
+    Image = None
+
 from .models import CaseTestModel, O2OCaseTestModel, FKCaseTestModel, Client
 
 
@@ -726,6 +732,7 @@ class CaseExpressionTests(TestCase):
             transform=attrgetter('integer', 'float')
         )
 
+    @unittest.skipUnless(Image, "Pillow not installed")
     def test_update_image(self):
         CaseTestModel.objects.update(
             image=Case(