diff --git a/server/books/tests/test_own_content_blocks.py b/server/books/tests/test_own_content_blocks.py
index a69ebb16..9a3f4c95 100644
--- a/server/books/tests/test_own_content_blocks.py
+++ b/server/books/tests/test_own_content_blocks.py
@@ -3,19 +3,19 @@ from graphene.test import Client
 from graphql_relay import to_global_id
 
 from api.schema import schema
-from api.utils import get_graphql_mutation
 from books.factories import ModuleFactory
 from books.models import Chapter, ContentBlock
+from core.tests.base_test import SkillboxTestCase
 from users.models import User, SchoolClass
 from users.services import create_users
 
 
-class OwnContentTestCase(TestCase):
+class OwnContentTestCase(SkillboxTestCase):
     def setUp(self):
         self.module = ModuleFactory()
         self.chapter = Chapter(title='Hello')
         self.module.add_child(instance=self.chapter)
-        create_users()
+        self.createDefault()
         content_block = ContentBlock(title='bla', slug='bla')
         self.chapter_id = to_global_id('ChapterNode', self.chapter.id)
         self.chapter.specific.add_child(instance=content_block)
@@ -26,6 +26,8 @@ class OwnContentTestCase(TestCase):
 
         request = RequestFactory().get('/')
         request.user = self.user
+        assert content_block.id is not None
+        self.content_block_id = to_global_id('ContentBlockNode', content_block.id)
 
         self.client = Client(schema=schema, context_value=request)
 
@@ -64,3 +66,79 @@ class OwnContentTestCase(TestCase):
         })
         self.assertEqual(len(result.get('data').get('chapter').get('contentBlocks')), 2)
 
+    def test_mutate_own_content_block(self):
+        query = """
+        query ContentBlockQuery($id: ID!) {
+            contentBlock(id: $id) {
+                contents
+                title
+            }
+        } 
+        """
+
+        res = self.get_client().get_result(query, variables={'id': self.content_block_id})
+        self.assertIsNone(res.errors)
+        self.assertEqual(res.data['contentBlock']['title'], 'bla')
+
+        mutation = """
+        mutation MutateContentBlock($input: MutateContentBlockInput!) {
+            mutateContentBlock(input: $input) {
+              contentBlock {
+                 contents
+                 title
+              } 
+            }
+        }
+        """
+
+        new_content = {
+            'id': '',
+            'type': 'text_block',
+            'value': {
+                'text': 'new text \n a new line'
+            }
+        }
+
+        variables = {
+            'input': {
+                'id': self.content_block_id,
+                'contentBlock': {
+                    'contents': [
+                        new_content
+                    ],
+                    'title': 'new title',
+                    'type': 'NORMAL'
+                }
+            }
+        }
+
+        mutation_result = self.get_client().get_result(mutation, variables=variables)
+        self.assertIsNone(mutation_result.errors)
+        content_block = mutation_result.data['mutateContentBlock']['contentBlock']
+        self.assertEqual(content_block['title'], 'new title')
+        self.assertEqual(content_block['contents'][0]['value']['text'], '<p>new text</p>\n<p>a new line</p>')
+
+        content_with_list = {
+            'id': '',
+            'type': 'text_block',
+            'value': {
+                'text': '<ul><li>Hallo</li><li>Velo</li></ul>'
+            }
+        }
+        other_variables = {
+            'input': {
+                'id': self.content_block_id,
+                'contentBlock': {
+                    'contents': [
+                        content_with_list
+                    ],
+                    'title': 'title for list content',
+                    'type': 'NORMAL'
+                }
+            }
+        }
+        list_mutation_result = self.get_client().get_result(mutation, variables=other_variables)
+        self.assertIsNone(list_mutation_result.errors)
+        content_block = list_mutation_result.data['mutateContentBlock']['contentBlock']
+        self.assertEqual(content_block['title'], 'title for list content')
+        self.assertEqual(content_block['contents'][0]['value']['text'], '<ul><li>Hallo</li><li>Velo</li></ul>')