Allow consumption of a relational database testcontainer through R2DBC

R2DBC is an initiative to establish a reactive API for relational database integration. It would be great to additionally consume a test container with a relational database through R2DBC by exposing the connection through a preconfigured ConnectionFactory.

ConnectionFactory is in R2DBC what a DataSource is in JDBC. R2DBC drivers are available for:

• PostgreSQL
• Microsoft SQL Server

More to come eventually.

Right now I can think of the following consumption scenarios:

• Pure JDBC (available today)
• JDBC and R2DBC (would make a lot of sense for testing as JDBC can help to prevent additional synchronization in cases where fixtures are prepared via JDBC and the actual application consumes data using reactive APIs)
• R2DBC-only (useful in pure reactive environments)

Comienza rastreando cómo los contenedores de prueba de bases de datos relacionales exponen actualmente el acceso JDBC y, después, compara el punto de entrada ConnectionFactory de R2DBC SPI enlazado en el issue. Se considera terminado cuando un contenedor de prueba de una base de datos relacional puede utilizarse mediante una ConnectionFactory preconfigurada, mientras los escenarios existentes de JDBC y los escenarios combinados de JDBC/R2DBC siguen estando disponibles.