Using shinytest2 with continuous integration

{shinytest2} can be used not only when developing applications locally – it can also be used with continuous integration (CI) platforms, such as GitHub Actions.

The rest of this document explains how to use {shinytest2} with GitHub in two use cases: with applications that stand alone (are not part of an R package), and with an application that are part of an R package.

Overview

The overall procedure for enabling tests on a CI platform is this:

Once you have set up continuous integration, the typical development cycle is this:

As you develop your application, it may also be appropriate to add, remove, or modify tests, or re-run tests and save new expected results.

A repository with a single application

For Shiny applications that aren’t part of an R package, there are two common ways that the repository will be set up:

  1. The repository contains one application, and the application files (like app.R and global.R) are contained at the top level of the repository.
  2. The repository contains more than one application files, and each application is contained in a subdirectory.

This section explains how to set up GHA to test a repository with a single application.

The directory structure of such a project will look something like this:

/
├── .github
│   └── workflows
│       └── check-app.yaml
├── .Rprofile
├── README.md
├── app.R
├── renv/activate.R
├── renv.lock
└── tests
    ├── testthat.R
    └── testthat
        ├── _snaps
        │   └── shinytest2
        │       ├── 001.json
        │       ├── 002.png
        │       ├── 003.json
        │       └── 004.png
        └── test-shinytest2.R

The files that you will need to add are described below.

check-app.yaml

This file contains information for GitHub Actions to build and test your application. It should look similar to this:

# Workflow derived from https://github.com/r-lib/actions/blob/v2-branch/examples/check-standard.yaml
# Need help debugging build failures? Start at https://github.com/r-lib/actions#where-to-find-help
on:
  push:
    branches: [main, master]
  pull_request:
    branches: [main, master]

name: test-app

jobs:
  test-app:
    runs-on: ${{ matrix.config.os }}

    name: ${{ matrix.config.os }} (${{ matrix.config.r }})

    strategy:
      fail-fast: false
      matrix:
        config:
          - {os: ubuntu-20.04, r: '4.1'}

    env:
      GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
      R_KEEP_PKG_SOURCE: yes

    steps:
      - uses: actions/checkout@v2

      - uses: r-lib/actions/setup-pandoc@v2

      - uses: r-lib/actions/setup-r@v2
        with:
          r-version: ${{ matrix.config.r }}
          http-user-agent: ${{ matrix.config.http-user-agent }}
          use-public-rspm: true

      - uses: r-lib/actions/setup-renv@v2

      - uses: rstudio/shinytest2/actions/test_app@v1
        with:
          path: "."

You should change the os and r version (set to ubuntu-20.04 and 4.1 above) to whatever operating system and R version is being used on the platform that your application will be deployed to.

renv.lock, renv/activate.R, .Rprofile

{renv} project-local dependency management system for projects. This is useful for Shiny applications where using specific package versions for all of your Shiny app dependencies. {renv} uses the same mechanism that is used by shinyapps.io and RStudio Connect.

{renv} auto-generates these three files using isrenv::init() and renv::snapshot().

File Usage
.Rprofile Used to activate {renv} for new R sessions launched in the project.
renv.lock The lockfile, describing the state of your project’s library at some point in time.
renv/activate.R The activation script run by the project .Rprofile.

To create .Rprofile and renv/activate.R, call renv::init() within your App project. To create / update renv.lock, call renv::snapshot().

Whenever you update packages on your development machine, you should run renv::snapshot() command again to make sure the packages used on GitHub stay in sync.

To learn more about {renv}, please see their Introduction to renv and Collaborating with renv articles.

An alternative to using {renv} is to create a DESCRIPTION file. This will not lock package versions; instead, it will use the latest version of each package from CRAN.

Running the first build

Once you’ve added these files, commit them and push to GitHub. This will trigger a build on GitHub Actions (GHA).

The first successful run of your workflow on GHA will generally take much longer than subsequent runs, because it needs to install all the R packages the first time. After a successful run, the packages are cached, so the builds should be much faster.

A repository with multiple applications

Another way to run your tests is using a repository with multiple applications, each in its own subdirectory.

The directory structure would look something like this:

/
├── .github
│   └── workflows
│       └── check-app.yaml
├── .Rprofile
├── README.md
├── renv/activate.R
├── renv.lock
├── 01_hello
│   ├── app.R
│   └── tests
│       ├── testthat.R
│       └── testthat
│           ├── _snaps
│           │   └── shinytest2
│           │       ├── 001.json
│           │       ├── 002.png
│           │       ├── 003.json
│           │       └── 004.png
│           └── test-shinytest2.R
└── 06_tabsets
    ├── app.R
    └── tests
        ├── testthat.R
        └── testthat
            ├── _snaps
            │   └── shinytest2
            │       ├── 001.json
            │       ├── 002.png
            │       ├── 003.json
            │       ├── 004.png
            │       ├── 005.json
            │       └── 006.png
            └── test-shinytest2.R

For a repository with this structure, the configuration is largely the same as a repository with a single app, as described above. The only difference is in the check-app.yaml file.

check-app.yaml

The check-app.yaml should have a step for each application in the respective directory, instead of testing just one application in the current directory.

      - uses: rstudio/shinytest2/check_app@v2
        with:
          path: "01_hello"
      - uses: rstudio/shinytest2/check_app@v2
        with:
          path: "06_tabsets"

Testing applications in a package

See the Using shinytest2 with R packages article.

Frequently asked questions

How do I add a status badge to my project?

See GitHub’s docs on adding a badge.

If your workflow file is named check-app.yaml in the schloerke/example-app repo, you can add a status badge to your GitHub to your README.md with the following line:

![check-app](https://github.com/schloerke/example-app/actions/workflows/check-app.yml/badge.svg)

In your README.md file, you can add a build status badge, like the one below, so that you can see the status of your code at a glance:

How do I use a DESCRIPTION file instead of {renv}?

Instead of using {renv}, you can use a DESCRIPTION file can be used to tell GHA which packages are needed to test the application. Instead of locking each package to a specific version like {renv}, this will result in the latest version of each package being downloaded from CRAN. This may be appropriate if you want to make sure your application works with the latest version of each package, instead of a frozen set of packages.

To use a DESCRIPTION file, you need to modify your check-app.yaml file to use r-lib/actions default package installation system instead of {renv}. Replace this line from the template provided above:

      - uses: r-lib/actions/setup-renv@v2

with

      - uses: r-lib/actions/setup-r-dependencies@v2

You will not want generate a renv.lock, .Rprofile, or other {renv} files, so do not run the {renv} commands listed above.

Next, create a DESCRIPTION file that looks something like this:

Imports:
  shiny,
  shinytest2

The Imports field must list all R packages that your application directly uses.

Normally the latest versions of the listed packages will be installed from CRAN. However, if you need to install development versions of packages from GitHub, that can be done by adding a Remotes section. For example:

Remotes:
  rstudio/shiny,
  rstudio/shinytest2@dev

This tells GitHub to install the {shiny} package from the main branch of https://github.com/rstudio/shiny, the {shinytest2} package from the dev branch of https://github.com/rstudio/shinytest2. In addition to branch names like dev, you can use commit hashes or tags.