Gemfile in u-observers-0.8.0 vs Gemfile in u-observers-0.9.0

@@ -1,14 +1,38 @@
 source 'https://rubygems.org'
 
 # Specify your gem's dependencies in u-observers.gemspec
 gemspec
 
-gem 'rake', '~> 12.0'
-gem 'minitest', '~> 5.0'
+activerecord_version = ENV.fetch('ACTIVERECORD_VERSION', '6.1')
 
+activerecord = case activerecord_version
+              when '3.2' then '3.2.22'
+              when '4.0' then '4.0.13'
+              when '4.1' then '4.1.16'
+              when '4.2' then '4.2.11'
+              when '5.0' then '5.0.7'
+              when '5.1' then '5.1.7'
+              when '5.2' then '5.2.3'
+              when '6.0' then '6.0.3'
+              end
+
+simplecov_version =
+  case RUBY_VERSION
+  when /\A2.[23]/ then '~> 0.17.1'
+  when /\A2.4/ then '~> 0.18.5'
+  else '~> 0.19'
+  end
+
+sqlite3 =
+  case activerecord
+  when /\A6\.0/, nil then '~> 1.4.0'
+  else '~> 1.3.0'
+  end
+
 group :test do
-  gem 'activerecord', require: 'active_record'
-  gem 'sqlite3'
+  gem 'minitest', activerecord_version < '4.1' ? '~> 4.2' : '~> 5.0'
+  gem 'simplecov', simplecov_version, require: false
 
-  gem 'simplecov', '~> 0.19', require: false
+  gem 'sqlite3', sqlite3
+  gem 'activerecord', activerecord, require: 'active_record'
 end