Drop support for Active Record 6.0 and older

This commit drops support for ancient Versions of Active Record.
Maintaining backwards compatibility with them became too expensive and
negatively influenced the pace of new development.

Assuming Active Record 6.1 or newer, we were able to remove certain
conditionals from the code base. Additionally, almost all mentions of
older versions of active record in the rails were removed from the code.

Author: gregnavis

.github/workflows/lint.yml

@@ -15,6 +15,6 @@ jobs:
       - uses: actions/checkout@v4
       - uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 3.0
+          ruby-version: "3.3"
           bundler-cache: true
       - run: bundle exec rake rubocop

.github/workflows/mysql.yml

@@ -92,7 +92,7 @@ jobs:
 
   test-unsupported:
     name: "Active Record ${{ matrix.active_record }} + Ruby ${{ matrix.ruby }}"
-    needs: [test-supported]
+    continue-on-error: true
     runs-on: ubuntu-latest
     services:
       mysql:

.github/workflows/postgresql.yml

@@ -95,7 +95,7 @@ jobs:
 
   test-unsupported:
     name: "Active Record ${{ matrix.active_record }} + Ruby ${{ matrix.ruby }}"
-    needs: [test-supported]
+    continue-on-error: true
     runs-on: ubuntu-latest
     services:
       postgres:

.rubocop.yml

@@ -1,7 +1,7 @@
 # We upgrade to new versions of rubocop manually so it won't harm to enable all
 # new cops.
 AllCops:
-  TargetRubyVersion: 2.4
+  TargetRubyVersion: 2.5
   NewCops: enable
   SuggestExtensions: false
 

Rakefile

@@ -18,14 +18,8 @@ end
 
 Bundler::GemHelper.install_tasks
 
-begin
-  require "rubocop/rake_task"
-rescue LoadError
-  # We don't mind not having Rubocop in CI when testing against an older version
-  # of Ruby and Rails.
-else
-  RuboCop::RakeTask.new
-end
+require "rubocop/rake_task"
+RuboCop::RakeTask.new
 
 require "rake/testtask"
 

active_record_doctor.gemspec

@@ -4,7 +4,7 @@ $LOAD_PATH.push File.expand_path("lib", __dir__)
 
 require "active_record_doctor/version"
 
-ACTIVE_RECORD_SPEC = ">= 4.2.0"
+ACTIVE_RECORD_SPEC = ">= 6.1.0"
 
 Gem::Specification.new do |s|
   s.name     = "active_record_doctor"
@@ -18,7 +18,7 @@ Gem::Specification.new do |s|
 
   s.metadata["rubygems_mfa_required"] = "true"
 
-  s.required_ruby_version = ">= 2.1.0"
+  s.required_ruby_version = ">= 2.5.0"
 
   s.add_dependency "activerecord", ACTIVE_RECORD_SPEC
 
@@ -28,10 +28,5 @@ Gem::Specification.new do |s|
   s.add_development_dependency "railties", ACTIVE_RECORD_SPEC
   s.add_development_dependency "rake", "~> 12.3.3"
   s.add_development_dependency "transient_record", "~> 2.0.0"
-
-  # We don't install rubocop in CI because we test against older Rubies that
-  # are incompatible with Rubocop.
-  if ENV["CI"].nil? || ENV["LINT"]
-    s.add_development_dependency "rubocop", "~> 1.57.1"
-  end
+  s.add_development_dependency "rubocop", "~> 1.57.1"
 end

lib/active_record_doctor/detectors/base.rb

@@ -136,8 +136,7 @@ def not_null_check_constraint_exists?(table, column)
       end
 
       def check_constraints(table_name)
-        # ActiveRecord 6.1+
-        if connection.respond_to?(:supports_check_constraints?) && connection.supports_check_constraints?
+        if connection.supports_check_constraints?
           connection.check_constraints(table_name).select(&:validated?).map(&:expression)
         elsif Utils.postgresql?(connection)
           definitions =
@@ -256,15 +255,8 @@ def each_foreign_key(table_name)
       end
 
       def each_table(except: [])
-        tables =
-          if ActiveRecord::VERSION::STRING >= "5.1"
-            connection.tables
-          else
-            connection.data_sources
-          end
-
         log("Iterating over tables") do
-          tables.each do |table|
+          connection.tables.each do |table|
             case
             when ignored?(table, except)
               log("#{table} - ignored via the configuration; skipping")

lib/active_record_doctor/detectors/missing_unique_indexes.rb

@@ -65,8 +65,7 @@ def validations_without_indexes
             # put true literally.
             case_sensitive = validator.options.fetch(:case_sensitive, true)
 
-            # ActiveRecord < 5.0 does not support expression indexes,
-            # so this will always be a false positive.
+            # Avoid a false positive if expression indexes are unsupported.
             next if !case_sensitive && Utils.expression_indexes_unsupported?
 
             validator.attributes.each do |attribute|

lib/active_record_doctor/utils.rb

@@ -12,9 +12,8 @@ def mysql?(connection = ActiveRecord::Base.connection)
       end
 
       def expression_indexes_unsupported?(connection = ActiveRecord::Base.connection)
-        (ActiveRecord::VERSION::STRING < "5.0") ||
-          # Active Record is unable to correctly parse expression indexes for MySQL.
-          (mysql?(connection) && ActiveRecord::VERSION::STRING < "7.1")
+        # Active Record is unable to correctly parse expression indexes for MySQL.
+        (mysql?(connection) && ActiveRecord::VERSION::STRING < "7.1")
       end
     end
   end

lib/generators/active_record_doctor/add_indexes/add_indexes_generator.rb

@@ -47,7 +47,7 @@ def content(table, indexes)
       # rubocop rule below.
 
       <<MIGRATION
-class IndexForeignKeysIn#{table.camelize} < ActiveRecord::Migration#{migration_version}
+class IndexForeignKeysIn#{table.camelize} < ActiveRecord::Migration[#{ActiveRecord::Migration.current_version}]
   def change
 #{add_indexes(table, indexes)}
   end
@@ -71,13 +71,5 @@ def add_index(table, columns)
         "    add_index :#{table}, #{columns.inspect}"
       end
     end
-
-    def migration_version
-      if ActiveRecord::VERSION::STRING >= "5.1"
-        "[#{ActiveRecord::Migration.current_version}]"
-      else
-        ""
-      end
-    end
   end
 end