What’s New in Rhino 1.11.0: Devmode, Auto Tests, and a New Destructure Operator

After a break, we are back with a fresh release of Rhino, packed with new features. Version 1.11.0 is focused on improving the developer experience and smoothing the usage of development tools available in Rhino.

Automated rerunning of the unit tests

With the new function rhino::auto_test_r() , users can set a watcher that will check for changes in R files. The watcher will rerun the unit tests upon detection, ensuring the proper reloading of the box modules. If a user changes one of the unit test files, the watcher will rerun only this file.

Tip: If running your unit tests takes too much time, you can set the filter parameter to run only the subset of files.

Custom reporter for unit tests

Now, both standard rhino::test_r and rhino::auto_test_r allow using different reporters to visualize the output of the tests:

Tip: rhino::test_r accepts all the arguments that you normally can pass to testthat::test_dir if you need more customization.

Devmode

Rhino now includes three tools that can work in a “watch” mode:

• rhino::build_sass for building your styles into app/static/css/app.min.css file
• rhino::build_js for building your JavaScript into app/static/js/app.min.js
• rhino::auto_test_r for running R unit tests (but you already know it from the previous section ;) )

Moreover, since version 1.7.0, Rhino has been supporting the autoreload option.

And now, it comes with a super handy single command to run all watchers and run the Rhino application in devmode, so all this can happen in a single R session. With this, your Rhino application will update automatically after every change, so you can see your progress live, without a need to manually restart the application every time.

Tip: In rhino::devmode You can pass arguments like filter or reporter to rhino::auto_test_r to customize the output of the unit tests.

Destructure operator (%<-%)

New Rhino comes with an experimental feature - a destructure operator that allows you to extract multiple named values from a list into individual variables in a single assignment:

# Create a list with named elements
config <- list(host = "localhost", port = 8080, debug = TRUE)

# Extract only what you need
c(host, port) %<-% config

The destructure operator particularly shines when working with Shiny modules. Here’s a practical example:

# app/view/module.R

box::use(
  shiny[div, moduleServer, NS, numericInput, reactive],
)

#' @export
ui <- function(id) {
  ns <- NS(id)
  div(
    numericInput(ns("number"), "Enter a number", value = 0),
    numericInput(ns("number2"), "Enter another number", value = 0),
  )
}

#' @export
server <- function(id) {
  moduleServer(id, function(input, output, session) {
    return(list(
      number = reactive(input$number),
      number2 = reactive(input$number2)
    ))
  })
}

‍

‍

# app/main.R

box::use(
  rhino[`%<-%`],
  shiny[div, moduleServer, NS, renderText, textOutput],
)

box::use(
  app/view/module,
)

#' @export
ui <- function(id) {
  ns <- NS(id)
  div(
    module$ui(ns("module")),
    textOutput(ns("result"))
  )
}

#' @export
server <- function(id) {
  moduleServer(id, function(input, output, session) {
    # Clean extraction of multiple reactive values
    c(number, number2) %<-% module$server("module")

    output$result <- renderText({
      paste0("Sum of ", number(), " and ", number2(), " is ", number() + number2())
    })
  })
}

In this example, the module’s server function returns a list of reactive values. The destructure operator provides a clean and intuitive way to extract these values into separate variables, making the code more readable and maintainable.

Bonus: Instructions for GitHub Copilot

In the Rhino documentation, you can now find a sample set of instructions that can be added to your project to improve work with LLM tools like GitHub Copilot. They will be automatically added to the prompt, and thanks to that, Copilot will be able to better understand how Rhino applications are built and provide better suggestions.

Upgrade to Rhino 1.11.0 today and join us at ShinyConf 2025 (April 9-11) to learn more about the Rhinoverse.