added db initialization to make sure the db exists and is up to date

before tests

spec/create_spec.rb

@@ -7,6 +7,12 @@ require 'sequel'
 require 'rspec'
 require 'rack/test'
 
+# DB initialization
+Sequel.extension :migration
+Sequel.sqlite("db/#{ENV['DB_NAME']}") do |db|
+  Sequel::Migrator.apply(db, "db/migrations")
+end
+
 def app
   App
 end