Test if string is not equal to either of two strings
This is a basic logic problem:
(a !=b) || (a != c) will always be true as long as b != c. Once you remember that in boolean logic
(x || y) == !(!x && !y)then you can find your way out of the darkness.
(a !=b) || (a != c) !(!(a!=b) && !(a!=c)) # Convert the || to && using the identity explained above!(!!(a==b) && !!(a==c)) # Convert (x != y) to !(x == y)!((a==b) && (a==c)) # Remove the double negationsThe only way for (a==b) && (a==c) to be true is for b==c. So since you have given b != c, the if statement will always be false.
Just guessing, but probably you want
<% if controller_name != "sessions" and controller_name != "registrations" %>
<% unless ['sessions', 'registrations'].include?(controller_name) %>or
<% if ['sessions', 'registrations'].exclude?(controller_name) %>