updates based on code review from @vaz

Gemfile

@@ -11,14 +11,15 @@ gem 'sinatra-activerecord'
 gem 'puma'
 gem 'tux'
 
-# These gems are only installed when RACK_ENV is either `development` or `test`
+# These gems are only installed when run as `bundle install --without production`
 group :development, :test do
   gem 'pry'
   gem 'shotgun'
   gem 'sqlite3'
 end
 
-# These gems are only installed when RACK_ENV is `production`
+# bundle install --without test --without development
 group :production do
-  gem 'pg'
+  # uncomment to use postgres in production, or move outside a group if your app uses postgres for development and production 
+  # gem 'pg'
 end

Gemfile.lock

@@ -24,7 +24,6 @@ GEM
     method_source (0.8.2)
     minitest (5.8.3)
     multi_json (1.11.2)
-    pg (0.18.4)
     pry (0.10.3)
       coderay (~> 1.1.0)
       method_source (~> 0.8.1)
@@ -77,7 +76,6 @@ PLATFORMS
 
 DEPENDENCIES
   activesupport
-  pg
   pry
   puma
   rake

config/database.rb

-configure do
 
-  case Sinatra::Application.environment
-  # Development database settings
-  when :development
-    # Log queries to STDOUT in development
-    ActiveRecord::Base.logger = Logger.new(STDOUT)
-    set :database, {
-      adapter: "sqlite3",
-      database: "db/db.sqlite3"
-    }
-  # Test database settings
-  when :test
-    set :database, {
-      adapter: "sqlite3",
-      database: "db/test.sqlite3"
-    }
-  # Production database settings, tuned for heroku
-  when :production
-    # Configure from a DATABASE_URL environment variable
-    db = URI.parse(ENV['DATABASE_URL'])  # standard heroku environment variable for configuring the database
+configure :development do
+  ActiveRecord::Base.logger = Logger.new(STDOUT)
+end
 
-    set :database, {
-      :adapter => db.scheme == 'postgres' ? 'postgresql' : db.scheme,
-      :host     => db.host,
-      :username => db.user,
-      :password => db.password,
-      :database => db.path[1..-1],
-      :encoding => 'utf8'
-    }
-  else
-    raise ArgumentError("Expected RACK_ENV to be: development, test or production")
-  end
+configure :development, :test do
+  set :database, {
+    adapter: 'sqlite3',
+    database: APP_ROOT.join('db', "#{Sinatra::Application.environment}.sqlite3")
+  }
+end
+
+configure :production do
+  db = URI.parse(ENV['DATABASE_URL'])  # standard heroku environment variable for configuring the database
 
+  set :database, {
+    :adapter => db.scheme == 'postgres' ? 'postgresql' : db.scheme,
+    :host     => db.host,
+    :username => db.user,
+    :password => db.password,
+    :database => db.path[1..-1],
+    :encoding => 'utf8'
+  }
+end
+
+configure do
   # Load all models from app/models, using autoload instead of require
   # See http://www.rubyinside.com/ruby-techniques-revealed-autoload-1652.html
   Dir[APP_ROOT.join('app', 'models', '*.rb')].each do |model_file|
     filename = File.basename(model_file).gsub('.rb', '')
     autoload ActiveSupport::Inflector.camelize(filename), model_file
   end
-
 end

config/environment.rb

@@ -8,8 +8,6 @@ require 'sinatra'
 require 'sinatra/activerecord'
 require 'sinatra/contrib/all' # Requires cookies, among other things
 
-
-ENV['RACK_ENV'] ||= 'development'
 APP_ROOT = Pathname.new(File.expand_path('../../', __FILE__))
 APP_NAME = APP_ROOT.basename.to_s
 
@@ -17,7 +15,6 @@ APP_NAME = APP_ROOT.basename.to_s
 configure do
   set :root, APP_ROOT.to_path
   set :server, :puma
-  set :environment, ENV['RACK_ENV'].to_sym
 
   enable :sessions
   set :session_secret, ENV['SESSION_KEY'] || 'lighthouselabssecret'