diff --git a/bibigrid/core/provider.py b/bibigrid/core/provider.py
index 360093ba..759c29f8 100644
--- a/bibigrid/core/provider.py
+++ b/bibigrid/core/provider.py
@@ -278,14 +278,45 @@ def get_security_group(self, name_or_id):
         @return:
         """
 
+    @abstractmethod
+    def create_volume(self, name, size, volume_type=None, description=None):
+        """
+        Creates a volume
+        @param name: name of the created volume
+        @param size: size of the created volume in GB
+        @param volume_type: depends on the location, but for example NVME or HDD
+        @param description: a non-functional description to help dashboard users
+        @return: the created volume
+        """
+
+    @abstractmethod
     def get_server(self, name_or_id):
         """
         Returns server if found else None.
         @param name_or_id:
         @return:
-        """  # TODO Test
+        """
+
+    @abstractmethod
+    def delete_volume(self, name_or_id):
+        """
+        Deletes the volume that has name_or_id.
+        @param name_or_id:
+        @return: True if deletion was successful, else False
+        """
+
+    @abstractmethod
+    def list_volumes(self):
+        """
+        Returns a list of all volumes on the provider.
+        @return: list of volumes
+        """
 
     def get_mount_info_from_server(self, server):
+        """
+        @param server: server to get the attachment list from
+        @return: list of dicts containing name and device node of all attached volumes
+        """
         volumes = []
         for server_volume in server["volumes"]:
             volume = self.get_volume_by_id_or_name(server_volume["id"])
diff --git a/bibigrid/openstack/openstack_provider.py b/bibigrid/openstack/openstack_provider.py
index db3350da..c50e85ad 100644
--- a/bibigrid/openstack/openstack_provider.py
+++ b/bibigrid/openstack/openstack_provider.py
@@ -344,10 +344,27 @@ def get_server(self, name_or_id):
         return self.conn.get_server(name_or_id)
 
     def create_volume(self, name, size, volume_type=None, description=None):
+        """
+        Creates a volume
+        @param name: name of the created volume
+        @param size: size of the created volume in GB
+        @param volume_type: depends on the location, but for example NVME or HDD
+        @param description: a non-functional description to help dashboard users
+        @return: the created volume
+        """
         return self.conn.create_volume(size=size, name=name, volume_type=volume_type, description=description)
 
     def delete_volume(self, name_or_id):
+        """
+        Deletes the volume that has name_or_id.
+        @param name_or_id:
+        @return: True if deletion was successful, else False
+        """
         return self.conn.delete_volume(name_or_id=name_or_id)
 
     def list_volumes(self):
+        """
+        Returns a list of all volumes on the provider.
+        @return: list of volumes
+        """
         return self.conn.list_volumes()
diff --git a/tests/unit_tests/provider/test_provider.py b/tests/unit_tests/provider/test_provider.py
index a3819b30..506d8275 100644
--- a/tests/unit_tests/provider/test_provider.py
+++ b/tests/unit_tests/provider/test_provider.py
@@ -228,12 +228,16 @@ def test_get_image_mismatch(self):
                 self.assertIsNone(provider.get_image_by_id_or_name("NONE"))
 
     def test_create_delete_volume(self):
+        """
+        Checks whether creation and deletion of volumes works
+        @return:
+        """
         for provider in PROVIDERS:
-            volume_id = provider.create_volume(name="ProviderTestVolume")
+            volume_id = provider.create_volume(name="test_create_delete_volume", size=1)
             self.assertTrue(volume_id)
             volume = provider.get_volume_by_id_or_name(volume_id)
             self.assertTrue(volume)
-            self.assertEqual("ProviderTestVolume", volume["name"])
+            self.assertEqual("test_create_delete_volume", volume["name"])
             self.assertTrue(provider.delete_volume(volume_id))
 
 
diff --git a/tests/unit_tests/startup_tests.py b/tests/unit_tests/startup_tests.py
index ddf569b5..a36464a2 100644
--- a/tests/unit_tests/startup_tests.py
+++ b/tests/unit_tests/startup_tests.py
@@ -37,7 +37,6 @@ def suppress_stdout():
     # Configuration at resources/tests/bibigrid_test.yaml
     # Needs to contain providers and infrastructures for the provider tests
     # You can use bibigrid_test_exmaple.yaml as the basis
-    print(os.path.abspath("."))
     suite = unittest.TestLoader().discover(start_dir=".", pattern='test_*.py')
     with suppress_stdout():
         unittest.TextTestRunner(verbosity=2).run(suite)