Add option to mute multiple database yaml warning

Adds an option to silence the warning that database configurations can
throw when it's unparsable.

actionmailbox/test/dummy/config/environments/development.rb

@@ -46,6 +46,10 @@ Rails.application.configure do
   # Highlight code that triggered database queries in logs.
   config.active_record.verbose_query_logs = true
 
+  # Show a warning when Rails couldn't parse your database.yml
+  # for multiple databases.
+  config.active_record.suppress_multiple_database_warning = false
+
   # Debug mode disables concatenation and preprocessing of assets.
   # This option may cause significant delays in view rendering with a large
   # number of complex assets.

actiontext/test/dummy/config/environments/development.rb

@@ -46,6 +46,10 @@ Rails.application.configure do
   # Highlight code that triggered database queries in logs.
   config.active_record.verbose_query_logs = true
 
+  # Show a warning when Rails couldn't parse your database.yml
+  # for multiple databases.
+  config.active_record.suppress_multiple_database_warning = false
+
   # Debug mode disables concatenation and preprocessing of assets.
   # This option may cause significant delays in view rendering with a large
   # number of complex assets.

activerecord/CHANGELOG.md

@@ -1,3 +1,8 @@
+*   Allow users to silence the "Rails couldn't infer whether you are using multiple databases..."
+    message using `config.active_record.suppress_multiple_database_warning`.
+
+    *Omri Gabay*
+
 *   Connections can be granularly switched for abstract classes when `connected_to` is called.
 
     This change allows `connected_to` to switch a `role` and/or `shard` for a single abstract class instead of all classes globally. Applications that want to use the new feature need to set `config.active_record.legacy_connection_handling` to `false` in their application configuration.

activerecord/lib/active_record/core.rb

@@ -131,6 +131,12 @@ module ActiveRecord
       # potentially cause memory bloat.
       mattr_accessor :warn_on_records_fetched_greater_than, instance_writer: false
 
+      ##
+      # :singleton-method:
+      # Show a warning when Rails couldn't parse your database.yml
+      # for multiple databases.
+      mattr_accessor :suppress_multiple_database_warning, instance_writer: false, default: false
+
       mattr_accessor :maintain_test_schema, instance_accessor: false
 
       class_attribute :belongs_to_required_by_default, instance_accessor: false

activerecord/lib/active_record/tasks/database_tasks.rb

@@ -154,7 +154,9 @@ module ActiveRecord
         begin
           Rails.application.config.load_database_yaml
         rescue
-          $stderr.puts "Rails couldn't infer whether you are using multiple databases from your database.yml and can't generate the tasks for the non-primary databases. If you'd like to use this feature, please simplify your ERB."
+          unless ActiveRecord::Base.suppress_multiple_database_warning
+            $stderr.puts "Rails couldn't infer whether you are using multiple databases from your database.yml and can't generate the tasks for the non-primary databases. If you'd like to use this feature, please simplify your ERB."
+          end
 
           {}
         end

railties/test/application/configuration_test.rb

@@ -1626,6 +1626,11 @@ module ApplicationTests
       assert_not ActiveRecord::Base.verbose_query_logs
     end
 
+    test "config.active_record.suppress_multiple_database_warning is false by default in development" do
+      app "development"
+      assert_not ActiveRecord::Base.suppress_multiple_database_warning
+    end
+
     test "config.annotations wrapping SourceAnnotationExtractor::Annotation class" do
       make_basic_app do |application|
         application.config.annotations.register_extensions("coffee") do |tag|
@@ -1865,6 +1870,23 @@ module ApplicationTests
       assert_equal({}, Rails.application.config.load_database_yaml)
     end
 
+    test "setup_initial_database_yaml does not print a warning if config.active_record.suppress_multiple_database_warning is true" do
+      app_file "config/database.yml", <<-YAML
+        <%= Rails.env %>:
+          username: bobby
+          adapter: sqlite3
+          database: 'dev_db'
+      YAML
+      add_to_config <<-RUBY
+        config.active_record.suppress_multiple_database_warning = true
+      RUBY
+      app "development"
+
+      assert_silent do
+        ActiveRecord::Tasks::DatabaseTasks.setup_initial_database_yaml
+      end
+    end
+
     test "raises with proper error message if no database configuration found" do
       FileUtils.rm("#{app_path}/config/database.yml")
       err = assert_raises RuntimeError do