add parallel_tests gem and update readme

Author: tsubik

Gemfile

@@ -111,6 +111,7 @@ group :development, :test do
   gem "debug", platforms: %i[mri mingw x64_mingw]
   gem "factory_bot_rails"
   gem "faker"
+  gem "parallel_tests"
   gem "rails-erd"
   gem "rubocop-rails"
   gem "standard"

Gemfile.lock

@@ -509,6 +509,8 @@ GEM
       activerecord (>= 6.1)
       request_store (~> 1.4)
     parallel (1.26.3)
+    parallel_tests (4.9.1)
+      parallel
     paranoia (3.0.0)
       activerecord (>= 6, < 8.1)
     parser (3.3.6.0)
@@ -842,6 +844,7 @@ DEPENDENCIES
   oj
   oj_mimic_json
   paper_trail
+  parallel_tests
   paranoia
   pg
   puma

README.md

@@ -150,6 +150,27 @@ Run rspec:
 bundle exec rspec
 ```
 
+You can also run tests in parallel. To do that you need to create a test database for each parallel process:
+
+```ruby
+bundle exec rake parallel:create
+bundle exec rake parallel:prepare
+```
+
+And then run the tests:
+
+```ruby
+bundle exec parallel:spec
+```
+
+To drop all test databases:
+
+```ruby
+bundle exec rake parallel:drop
+```
+
+For more information about parallel tests check [parallel_tests gem.](https://github.com/grosser/parallel_tests)
+
 ## DOCUMENTATION ##
 
 ### API ###

config/database.yml

@@ -15,7 +15,7 @@ development:
 
 test:
   <<: *default
-  database: fti_test
+  database: fti_test<%= ENV['TEST_ENV_NUMBER'] %>
 
 e2e:
   <<: *default