[File] raise DuplicateName as in all other create methods

Author: jgrewe

nixio/file.py

@@ -419,7 +419,7 @@ def create_block(self, name="", type_="", compression=Compression.Auto,
             return self.blocks[entity_id]
 
         if name in self._data:
-            raise ValueError("Block with the given name already exists!")
+            raise DuplicateName("Block with the given name already exists!")
         if compression == Compression.Auto:
             compression = self._compr
         block = Block.create_new(self, self._data, name, type_, compression)

nixio/test/test_file.py

@@ -13,6 +13,7 @@
 import time
 
 import nixio as nix
+from nixio.exceptions.exceptions import DuplicateName
 import nixio.file as filepy
 from nixio.exceptions import InvalidFile
 from .tmp import TempDir
@@ -47,7 +48,8 @@ def test_file_blocks(self):
         assert len(self.file.blocks) == 0
 
         block = self.file.create_block("test block", "recordingsession")
-
+        with self.assertRaises(DuplicateName):
+            self.file.create_block("test block", "recordingsession")
         assert len(self.file.blocks) == 1
 
         assert block in self.file.blocks