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, 10 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
index e6302112de..3a1edfc855 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
@@ -98,6 +98,16 @@ module ActiveRecord
         configure_connection
       end
 
+      def self.database_exists?(config)
+        config = config.symbolize_keys
+        if config[:database] == ":memory:"
+          return true
+        else
+          database_file = defined?(Rails.root) ? File.expand_path(config[:database], Rails.root) : config[:database]
+          File.exist?(database_file)
+        end
+      end
+
       def supports_ddl_transactions?
         true
       end