How do I make has_secure_password (bcrypt hashes) faster in Rails

Question

Another self-answer for posterity. :)

Creating models with has_secure_password (which uses a bcrypt hash) is really slow. User.create! takes about 0.3 seconds.

This slows down my test suite. How do I improve performance?

Answer 1

Semyon Perepelitsa graciously posted the following snippet for test_helper/spec_helper:

require "bcrypt"
silence_warnings do
  BCrypt::Engine::DEFAULT_COST = BCrypt::Engine::MIN_COST
end

This weakens the hash function, making hash calculation near-instantaneous in test mode - just what we want!