Add database_exists? method to connection adapters

When SQLite connects it will silently create a database if the database does not
exist. This behaviour causes different issues because of inconsistent behaviour
between adapters: #36383, #32914. This commit adds a `database_exists?` method
as a way to check the database without creating it. This is a stepping stone to
fully resolving the above issues.

1 files changed, 6 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
index 53510c62c2..d9eab9582e 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
@@ -42,6 +42,12 @@ module ActiveRecord
         configure_connection
       end
 
+      def self.database_exists?(config)
+        !!ActiveRecord::Base.mysql2_connection(config)
+      rescue ActiveRecord::NoDatabaseError
+        false
+      end
+
       def supports_json?
         !mariadb? && database_version >= "5.7.8"
       end