Using shiny::withProgress outside of Shiny.

[chasec]

I now have a few shiny apps (written as packages) that use 'meta-functions' that pipeline other functions and use shiny::withProgress to update progress.

Example:

copyToNewDatabase <- function(existingDBPool,
                            newDBPool,
                            sampleIDs){

shiny::withProgress(message = 'Copying data to new database',
                    detail = 'Connecting experiments...',
                    value = 0, {
                      
                      someFunction(...)
                      
                      setProgress(value = 0.2, 
                                  message = 'Copying data to new database',
                                  detail = 'Setting up new experiment...',
                                  session = getDefaultReactiveDomain())  
                      someFunction(...)
                    }
}

copyToNewDatabase()

However these meta-functions are un-testable outside of a shiny session and so to make that work we can change how that is written to something like:

copyToNewDatabase <- function(existingDBPool,
                            newDBPool,
                            sampleIDs){

someFunction(...)

if (!exists("session")) {
  shiny::setProgress(value = 0.2, 
                     message = 'Copying data to new database',
                     detail = 'Setting up new experiment...',
                     session = getDefaultReactiveDomain()) 
}

someFunction(...)
}


shiny::withProgress(message = 'Copying data to new database',
                  detail = 'Connecting experiments...',
                  value = 0, {
                    
                    copyToNewDatabase()
                    
                  }

Obviously testing whether session exists is not a solution to this problem.

• Is there a better way for testing whether the function is being run inside a shiny session?
• Maybe there's some way to make these functions withProgress / setProgress available for use outside of a shiny session (e.g. just throws warnings outside of a shiny session), so that the behavior can be better tested (eg with testthat).