Load the model schema when running test in eager load context

Some protections like the one that checks if an enum is pointing to
a valid column in the table only works when the database schema is
loaded to the model.

Before this change, if schema cache wasn't present and the right
combinations of configurations were not set, developers would only see
this exception in production.

With this change, those errors would be caught on CI, as soon the
tests are loaded.

activerecord/lib/active_record/model_schema.rb

@@ -553,6 +553,20 @@ def reset_column_information
         initialize_find_by_cache
       end
 
+      def load_schema # :nodoc:
+        return if schema_loaded?
+        @load_schema_monitor.synchronize do
+          return if @columns_hash
+
+          load_schema!
+
+          @schema_loaded = true
+        rescue
+          reload_schema_from_cache # If the schema loading failed half way through, we must reset the state.
+          raise
+        end
+      end
+
       protected
         def initialize_load_schema_monitor
           @load_schema_monitor = Monitor.new
@@ -594,20 +608,6 @@ def schema_loaded?
           defined?(@schema_loaded) && @schema_loaded
         end
 
-        def load_schema
-          return if schema_loaded?
-          @load_schema_monitor.synchronize do
-            return if @columns_hash
-
-            load_schema!
-
-            @schema_loaded = true
-          rescue
-            reload_schema_from_cache # If the schema loading failed half way through, we must reset the state.
-            raise
-          end
-        end
-
         def load_schema!
           unless table_name
             raise ActiveRecord::TableNotSpecified, "#{self} has no table configured. Set one with #{self}.table_name="

railties/lib/rails/test_help.rb

@@ -22,6 +22,12 @@
     exit 1
   end
 
+  if Rails.configuration.eager_load
+    ActiveRecord::Base.descendants.each do |model|
+      model.load_schema unless model.abstract_class?
+    end
+  end
+
   ActiveSupport.on_load(:active_support_test_case) do
     include ActiveRecord::TestDatabases
     include ActiveRecord::TestFixtures

railties/test/application/test_test.rb

@@ -317,6 +317,39 @@ class UserTest < ActiveSupport::TestCase
       assert_not_includes output, "after:"
     end
 
+    test "schema for all the models is loaded when tests are run in eager load context" do
+      output = rails("generate", "model", "user", "name:string")
+      version = output.match(/(\d+)_create_users\.rb/)[1]
+
+      app_file "db/schema.rb", <<-RUBY
+        ActiveRecord::Schema.define(version: #{version}) do
+          create_table :users do |t|
+            t.string :name
+          end
+
+          create_table :action_text_rich_texts
+          create_table :active_storage_variant_records
+          create_table :active_storage_blobs
+          create_table :active_storage_attachments
+          create_table :action_mailbox_inbound_emails do |t|
+            t.integer :status
+          end
+        end
+      RUBY
+
+      app_file "config/initializers/enable_eager_load.rb", <<-RUBY
+        Rails.application.config.eager_load = true
+      RUBY
+
+      app_file "app/models/user.rb", <<-RUBY
+        class User < ApplicationRecord
+          enum :type, [:admin, :user]
+        end
+      RUBY
+
+      assert_unsuccessful_run "models/user_test.rb", "Unknown enum attribute 'type' for User"
+    end
+
     private
       def assert_unsuccessful_run(name, message)
         result = run_test_file(name)