DEV: Introduce parallel rspec testing

Adds the parallel_tests gem, and redis/postgres configuration for running rspec tests in parallel. To use:

```
rake parallel:rake[db:create]
rake parallel:rake[db:migrate]
rake parallel:spec
```

This brings the test suite from 12m20s to 3m11s on my macOS machine

.rspec_parallel

@@ -0,0 +1,4 @@
+--format progress
+--format ParallelTests::RSpec::RuntimeLogger --out tmp/parallel_runtime_rspec.log
+--format ParallelTests::RSpec::SummaryLogger --out tmp/spec_summary.log
+--format ParallelTests::RSpec::FailuresLogger --out tmp/failing_specs.log

Gemfile

@@ -140,6 +140,7 @@ group :test, :development do
   gem 'pry-nav'
   gem 'byebug', require: ENV['RM_INFO'].nil?
   gem 'rubocop', require: false
+  gem 'parallel_tests'
 end
 
 group :development do

Gemfile.lock

@@ -276,6 +276,8 @@ GEM
       ruby-openid
     optimist (3.0.0)
     parallel (1.13.0)
+    parallel_tests (2.28.0)
+      parallel
     parser (2.6.0.0)
       ast (~> 2.4.0)
     pg (1.1.4)
@@ -524,6 +526,7 @@ DEPENDENCIES
   omniauth-twitter
   onebox (= 1.8.82)
   openid-redis-store
+  parallel_tests
   pg
   pry-nav
   pry-rails

app/models/global_setting.rb

@@ -236,6 +236,10 @@ def keys
 
   class BlankProvider < BaseProvider
     def lookup(key, default)
+
+      if key == :redis_port
+        return ENV["DISCOURSE_REDIS_PORT"] if ENV["DISCOURSE_REDIS_PORT"]
+      end
       default
     end
 

config/boot.rb

@@ -28,3 +28,19 @@
     )
   end
 end
+
+# Parallel spec system
+if ENV['RAILS_ENV'] == "test" && ENV['TEST_ENV_NUMBER']
+  n = ENV['TEST_ENV_NUMBER'].to_i
+  port = 10000 + n
+
+  puts "Setting up parallel test mode - starting Redis #{n} on port #{port}"
+
+  `rm -rf tmp/test_data_#{n} && mkdir -p tmp/test_data_#{n}/redis`
+  pid = Process.spawn("redis-server --dir tmp/test_data_#{n}/redis --port #{port}", out: "/dev/null")
+
+  ENV["DISCOURSE_REDIS_PORT"] = port.to_s
+  ENV["RAILS_DB"] = "discourse_test_#{ENV['TEST_ENV_NUMBER']}"
+
+  at_exit { puts "Terminating redis #{n}"; Process.kill("SIGTERM", pid); Process.wait }
+end