Use variable

Author: j-t-1

tests/test_writer.py

@@ -301,7 +301,7 @@ def test_insert_blank_page():
 
     old_page_count = len(writer.pages)
     old_page = writer.pages[old_page_count - 1]
-    page = writer.insert_blank_page(width=None, height=42, index=len(writer.pages))
+    page = writer.insert_blank_page(width=None, height=42, index=old_page_count)
     assert page.mediabox.width == old_page.mediabox.width
     assert page.mediabox.height == 42