Create a test context, set and query the default context.
make_context(drv, connect_args, set_as_default = TRUE, tweaks = NULL,
  name = NULL)set_default_context(ctx)
get_default_context()
[DBIDriver] An expression that constructs a DBI driver,
like SQLite().
[named list] Connection arguments (names and values).
[logical(1)] Should the created context be
set as default context?
[DBItest_tweaks] Tweaks as constructed by the
tweaks() function.
[character] An optional name of the context which will
be used in test messages.
[DBItest_context] A test context.
[DBItest_context] A test context, for
set_default_context the previous default context (invisibly) or
NULL.