Are Rails passwords generated with bcrypt portable?

Are Rails passwords generated with bcrypt portable?

I have an existing web application with a few thousand users which I'm
porting over to Rails. As I rewrite and refactor this app I may need to
run it on any number of different servers for development, testing, and
production purposes.
I'm using Rails' built-in has_secure_password method in my user model but
I'm concerned about the portability of password data. I will need to move
the contents of my database from machine to machine to test in different
environments and its very important that I can test the user
authentication functionality using the same set of users and passwords in
each environment.
So far its easy to find answers about how bcrypt-ruby works along with
Rails has_secure_password but after weeks of searching I haven't found a
clear answer.
If has_secure_password results in a WorkFactor + Salt + HashedPassword
concatenated and saved to the password_digest database column then can
that hash be regenerated and compared reliably if moved to any other
machine (assuming any other machine is running Rails on a Unix-like OS)?
OR To put it another way - are bcrypt-ruby passwords generated with Rails'
has_secure_password portable?
Follow up question: If the salt is always generated randomly (I've seen
the same password use different hashes so I don't think the salt is
created from the text of the password itself) then how would a Rails app
be able to reliably rehash the password on a login form submit and compare
it to what's in the database. Obviously it would have to know what the
salt is first in order to compare it. How does it do that?