Shiny in Production

A Shiny application that dazzles in development can still fall apart in production if user journeys break, data pipelines drift, or browsers behave unexpectedly. Automated end-to-end (E2E) testing is the safety net that keeps released apps robust, and Playwright is quickly becoming the gold-standard tool for doing it across Chrome, Firefox and WebKit. In this hands-on workshop we’ll walk through a workflow for writing, running and maintaining Playwright tests that keep your Shiny apps ship-shape long after launch.

Here’s what we’ll tackle:

• why E2E testing matters even when you already have unit tests
• installing and configuring Playwright in a golem project using {pw}
• scripting core user flows—clicks, inputs...
• validating data and UI state with snapshots and assertions
• running tests headlessly in CI pipelines (GitHub Actions, GitLab CI, Posit Connect)
• handling Shiny specificity
• debugging failed tests

For this workshop, bring a laptop and a Shiny app you care about. You’ll leave with a working Playwright test harness you can drop straight into your projects — plus the confidence to deploy on Friday without fear.

By the end of the workshop, participants will…

• understand the role of end-to-end testing in the Shiny deployment pipeline
• be able to install Playwright and scaffold tests from R
• write expressive Playwright scripts that capture user journeys in a Shiny app
• run tests in parallel across browsers locally and in continuous-integration systems

Imagine you couldn’t register to attend “Shiny in Production” if someone else was in the process of registering, and you had to wait until they had finished before you could click to “Buy tickets on EventBrite”. This kind of “blocking” shouldn’t happen in modern web applications but is surprisingly common in Shiny applications. It happens because a single R process handles all of the server-side processing for multiple users—one long-running task can prevent any other task from proceeding, hampering interactivity both between and within user-sessions.

Fortunately, Shiny’s support for asynchronous programming can alleviate this problem. In the asynchronous approach, you start tasks running without having to wait for them to complete. But, this requires a change in mindset for many programmers and there are a few concepts to understand before you can take advantage of this approach. So, what are you waiting for? Sign up for this workshop!

By the end of the workshop, participants will:

• understand how within-session and between-session blocking can arise in a Shiny app
• understand the basics of asynchronous computation
• solve between-session blocking with future/promise
• solve blocking the modern way, with ExtendedTask

Maps can be a visually striking way to present data in a Shiny application. With {leaflet}, you can add markers, icons or shapes to highlight specific places, or colour regions of a map according to data values. The user can zoom to focus on areas of interest. In this workshop you will learn how to present geographic data in a shiny application. We will also show some pitfalls that may arise when you try to make shiny do too much work when a map is recreated or updated.

By the end of the workshop, participants will be able to:

• create a map using {leaflet}
• embed maps in Shiny
• plot markers over a map to highlight points of interest
• colour geographic regions according to data values
• add legends and other annotations to a map
• efficiently update an existing map using leafletProxy()

Applications should look attractive, be engaging, and work intuitively for users. All of these aspects benefit from spending time focussing on user-interface (UI) and user experience (UX) design during app development. Indeed, we find that clients provide lots of feedback on the look and feel of an app, and that it is useful to prepare a view of the overall design even before any interactive functionality is implemented, so that design feedback can be obtained as early as possible.

Graphical tools like Figma allow the designer to build both coarse- and fine-grained illustrations of how an application or website will look, and simulate the user workflow through the application. The designs can be shared with clients, and feedback gathered through comments pinned to the design.

This workshop requires no prior experience in UI/UX design and will guide you through your first steps in Figma, demonstrating how to quickly prepare design ideas for Shiny applications. We’ll also get you started with creating some components—reusable modules of your design that can transition into different states. You will need a Figma account to participate; there is a free-tier that is sufficient for the workshop.

During this workshop, participants will:

• create simple wireframe designs in Figma
• set font styles and colour palettes consistently across your design
• use the bootstrap UI kit in Figma
• create small components with a simple transition into an alternative state
• use CSS to replicate a simple Figma design in Shiny