Fix unit tests

server/books/migrations/0010_auto_20190312_1306.py

@@ -0,0 +1,18 @@
+# Generated by Django 2.0.6 on 2019-03-12 13:06
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('books', '0009_topic_vimeo_id'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='topic',
+            name='vimeo_id',
+            field=models.CharField(blank=True, default=None, max_length=200, null=True),
+        ),
+    ]

server/books/models/topic.py

@@ -18,7 +18,7 @@ class Topic(StrictHierarchyPage):
     order = models.PositiveIntegerField(null=False, blank=False, help_text='Order of the topic')
     teaser = models.TextField()
     description = RichTextField(features=DEFAULT_RICH_TEXT_FEATURES)
-    vimeo_id = models.CharField(max_length=200, null=True, default=None)
+    vimeo_id = models.CharField(max_length=200, blank=True, null=True, default=None)
 
     content_panels = [
         FieldPanel('title', classname="full title"),