I tried it both ways. If I return 0s I get more errors in random tests. If I return "" I get less errors. But still get errors

0 is quantity.
If I live code like this:
if check == 0:
return ''
I get errors like:
'' should equal '(P : 0)'.

If I do this:
#if check == 0:
# return ''
If get errors:
'(H : 0) - (Q : 0)' should equal ''

To me it looks like random test is wrong.

1. '(W : 0)' should equal ''

2. '' should equal '(W : 0)'

if I make it return '' when there are 0 it gives error 2. If I return number of books it gives error 1