Drop EOL Ruby and Rails versions.

.travis.yml

@@ -6,23 +6,14 @@ addons:
   postgresql: 9.6
 gemfile:
   - Gemfile
-  - Gemfile.rails42
-  - Gemfile.rails50
-  - Gemfile.rails52
   - Gemfile.rails60
   - Gemfile.mongo_mapper
 rvm:
-  - 2.2.9
-  - 2.3.6
-  - 2.4.3
-  - 2.5.0
-  - jruby-9.1.14.0
+  - 2.5.8
+  - 2.6.6
+  - 2.7.1
 before_install:
-  # Rubygems > 3.0.0 no longer supported rubies < 2.3
-  - gem install "rubygems-update:<3.0.0" --no-document && update_rubygems
-  # Bundler 2.0 is not supported by Rails < 5
-  - gem list -i bundler -v '>= 2.0.0' && rvm @global do gem uninstall bundler -x || true
-  - gem install bundler -v '< 2'
+  - gem install bundler
 env:
   global:
     - DB_USER=postgres
@@ -32,17 +23,9 @@ env:
     - DB=postgresql
 matrix:
   fast_finish: true
-  allow_failures:
-    - rvm: jruby-9.1.14.0
   exclude:
     - gemfile: Gemfile.mongo_mapper
       env: DB=postgresql
-    - rvm: 2.2.9
-      gemfile: Gemfile.rails60
-    - rvm: 2.3.6
-      gemfile: Gemfile.rails60
-    - rvm: 2.4.3
-      gemfile: Gemfile.rails60
 branches:
   only:
     - master

Gemfile

@@ -1,8 +1,6 @@
 eval_gemfile('Gemfile.global')
 
 gem 'minitest', '~> 5.8'
-gem 'rails',    '5.1.4', require: false
-gem 'activerecord-jdbcsqlite3-adapter', '~> 51.0', platform: :jruby
-gem 'activerecord-jdbcpostgresql-adapter', '~> 51.0', platform: :jruby
+gem 'rails',    '~> 5.2.4', require: false
 gem 'mongoid'
 gem 'sqlite3', '~> 1.3.6', :platform => [:ruby, :mswin, :mingw]

Gemfile.mongo_mapper

@@ -1,8 +1,6 @@
 eval_gemfile('Gemfile.global')
 
 gem 'minitest', '~> 5.8'
-gem 'rails',    '4.2.8', :require => false
-gem 'activerecord-jdbcsqlite3-adapter', '~> 1.3.0', platform: :jruby
-gem 'activerecord-jdbcpostgresql-adapter', '~> 1.3.0', platform: :jruby
+gem 'rails',    '~> 5.2.4', :require => false
 gem 'mongo_mapper'
 gem 'sqlite3', '~> 1.3.6', :platform => [:ruby, :mswin, :mingw]

Gemfile.rails60

@@ -2,7 +2,5 @@ eval_gemfile('Gemfile.global')
 
 gem 'minitest', '~> 5.8'
 gem 'rails',    '~> 6.0.0', require: false
-gem 'activerecord-jdbcsqlite3-adapter', github: 'jruby/activerecord-jdbc-adapter', branch: 'master', platform: :jruby
-gem 'activerecord-jdbcpostgresql-adapter', github: 'jruby/activerecord-jdbc-adapter', branch: 'master', platform: :jruby
 gem 'mongoid',  github: 'mongodb/mongoid'
 gem 'sqlite3', :platform => [:ruby, :mswin, :mingw]

test/mongo_mapper_test.rb

@@ -8,8 +8,7 @@
   require 'mongo_mapper'
 end
 
-MongoMapper.connection = Mongo::Connection.new('localhost', 27017)
-MongoMapper.database   = 'enumerize-test-suite-of-mongomapper'
+MongoMapper.connection = Mongo::Client.new(['localhost:27017'], database: 'enumerize-test-suite-of-mongomapper')
 
 describe Enumerize do
   class MongoMapperUser