Move all necessary dependencies into default Gemfile

Gemfiles other than the default one now only test against alternate
Rails versions but they skip Sequel, DM, and Mongo tests.

Gemfile

@@ -9,10 +9,16 @@ gem 'rspec', '~> 2.99'
 gem 'mocha', '~> 0.9.8'
 
 gem 'sqlite3', '~> 1.4.0'
-
 gem 'mysql2', '~> 0.5.2', :group => :mysql
 gem 'pg', '~> 0.18.4', :group => :pg
 
+gem 'sequel', '~> 5.29'
+gem 'dm-core'
+gem 'dm-aggregates'
+gem 'dm-migrations'
+gem 'dm-sqlite-adapter'
+gem 'mongoid', '~> 7.0.4'
+
 group :development do
   gem 'debugger', :platforms => :mri_19
 end

Gemfile.rails5.2

@@ -9,13 +9,6 @@ gem 'rspec', '~> 2.99'
 gem 'mocha', '~> 0.9.8'
 
 gem 'sqlite3', '~> 1.3.6'
-gem 'sequel', '~> 5.29'
-gem 'dm-core'
-gem 'dm-aggregates'
-gem 'dm-migrations'
-gem 'dm-sqlite-adapter'
-gem 'mongoid', '~> 7.0.4'
-
 gem 'mysql2', '~> 0.5.2', :group => :mysql
 gem 'pg', '~> 0.18.4', :group => :pg
 

script/test_all

@@ -11,7 +11,7 @@ if [ -z "$BUNDLE_GEMFILE" ]; then
   BUNDLE_GEMFILE="$(bundle config gemfile | grep BUNDLE_GEMFILE | head -1 | cut -d'"' -f2)"
 fi
 
-if [[ -n "$BUNDLE_GEMFILE" && "${BUNDLE_GEMFILE##*/}" != 'Gemfile.rails5.2' ]]; then
+if [[ -n "$BUNDLE_GEMFILE" && "${BUNDLE_GEMFILE##*/}" != 'Gemfile' ]]; then
   export SKIP_NONRAILS_TESTS=1
 fi