Created the set of unit tests (specs) for ColumnTypeValidator class.
Created the set of unit tests (specs) for build SQL functionality altering existing columns.
Configured logger infrastructure for Helper class. Increased the version number for Gauge app.
Added SQL script generating code to column length, nullability, and default constraint validators.
Moved method creating SQL column attributes from SQL::Builder to DataColumsSchema class.
Created the set of unit tests (specs) covered SQL script generation for data column length and nullability validators.
Created build_alter_column_sql method constructing SQL statement to alter the specified data column.
Moved all functionality building SQL script to alter data columns to base validator class.
Created method placeholders in SQL::Builder class generating SQL code to drop and recreate check and default constraints.
Implemented current method in DB::Adapter class allowing to communicate with Sequel database object.