Category: Testing

Russ Hyde wraps up a series on shinytest2:

UI-driven end-to-end tests require a bit more code than unit tests. For example, starting the app and navigating around to set up some initial state will require a few lines of code. But these are things you’ll likely need to do in several tests. As you add more and more test cases and these commonalities reveal themselves, it pays to extract out some helper functions and / or classes. By doing so, your tests will look simpler, the behaviour that you are testing will be more explicit, and you’ll have less code to maintain. We’ll show some software designs that may simplify your {shinytest2} code.

This post builds upon the previous posts in the series, but is quite a bit more technical than either of them. In addition to shiny development, you’ll need to know how to define functions in R and for the last section you’ll need to know about object-oriented programming in R (specifically using R6). The ideas in that section may be of interest even if you aren’t fluent with R6 classes yet.

Click through for the series finale.

Russ Hyde continues a series on shinytest2:

Here, we will write a simple shiny app (as an R package) and show how to generate tests for this app using {shinytest2}. As discussed in the previous post, {shinytest2} tests your app as if a user was interacting with it in their browser. The tests generated are application-focussed rather than component-focussed and so give some overall guarantees on how the app should behave.

This post is slightly more technical than the last, and assumes that the reader is comfortable with creating and unit-testing packages in R, and with shiny development in general.

Click through to see the code, as well as plenty of explanation.

Russ Hyde begins a new series:

{shinytest2} builds upon the {shinytest} package and was written by Barret Schloerke and his colleagues at RStudio. Like puppeteer, {shinytest2} uses the Chrome DevTools Protocol to interact with the browser, which is a pretty stable basis for building a browser automation tool (the predecessor {shinytest} was built on a now-unsupported browser library called PhantomJS, so we strongly recommend migrating to {shinytest2} if you are still using {shinytest}). Test scripts are written in R and so should be accessible to R developers who are comfortable with {testthat}. There is an automated tool (described in the next post) for creating these test scripts. Also, {shinytest2} understands the architecture of shiny apps, and so it is simple to access the input and output variables that are stored by a shiny app at any given time, the inputs can be modified easily as well – to access these variables using the more general UI-based end-to-end testing tools is much more difficult.

Read on for the “why” behind this series and the next posts will get into more of the “how.”