RMariaDB examples and tests connect to a database defined by the
rs-dbi group in ~/.my.cnf. This function checks if that
database is available, and if not, displays an informative message.
mariadbDefault() works similarly but throws a testthat skip condition
on failure, making it suitable for use in tests.
Examples
if (mariadbHasDefault()) {
db <- dbConnect(RMariaDB::MariaDB(), dbname = "test")
dbListTables(db)
dbDisconnect(db)
}