modified the deletion logic as per the comments and setting the readonly cell to false

notebook/tests/selenium/test_deletecell.py

@@ -3,9 +3,9 @@ def cell_is_deletable(nb, index):
     JS = 'return Jupyter.notebook.get_cell({}).is_deletable();'.format(index)
     return nb.browser.execute_script(JS)
 
-def remove_cells(notebook):
-    for i in notebook.cells:
-        notebook.delete_cell(notebook.index(i))
+def remove_all_cells(notebook):
+    for i in range(len(notebook.cells)):
+        notebook.delete_cell(0)
 
 def test_delete_cells(notebook):
     a = 'print("a")'
@@ -56,5 +56,6 @@ def test_delete_cells(notebook):
     assert len(notebook.cells) == 2
     assert cell_is_deletable(notebook, 1)
 
-    remove_cells(notebook)
+    notebook.set_cell_metadata(0, 'deletable', 'true')  # to perform below test, remove all the cells
+    remove_all_cells(notebook)
     assert len(notebook.cells) == 1    # notebook should create one automatically on empty notebook