Adds a function or a local variable to RUnit global logger.
addToLogger(name, value, logger = NULL)the modified logger object. Note that the global object is also
modified if logger is NULL.
name of the function or variable to add
object to append to the logger.
If value is a function it is added to the list and is accessible via
.testLogger$name.
If value is a variable it is added to the local environment and is
therefore accessible in all logging functions.
an optional RUnit logger object.
If missing or NULL, the object .testLogger is searched in
.GlobalEnv -- and an error is thrown if it does not exist.