app_support: Attach the Shiny application's support environment

In shinytest2: Testing for Shiny Applications

Attach the Shiny application's support environment

Description

Executes all ./R files and global.R from a Shiny application directory into an environment that is attached appropriately. This is useful when you need access to helper functions, modules, or values created in the ./R folder for testing purposes.

Usage

local_app_support(app_dir, envir = rlang::caller_env())

with_app_support(app_dir, expr, envir = rlang::caller_env())

load_app_support(app_dir, envir = rlang::caller_env())

Arguments

app_dir	The base directory for the Shiny application.
envir	The environment in which the App support should be made available.
expr	An expression to evaluate within the support environment.

Functions

• local_app_support(): Temporarily attach the Shiny application's support environment into the current environment.

• with_app_support(): For the provided expr, attach the Shiny application's support environment into the current environment.

• load_app_support(): Loads all support files into the current environment. No cleanup actions are ever performed.

When to use these functions

For inline apps (app objects passed directly to AppDriver): You do NOT need these functions. Since your test file already has access to your package functions (via library(yourpackage) or devtools::load_all()), you can reference them directly when creating the app object.

For apps with separate support files: Use these functions when your app is stored in a directory (e.g., ⁠inst/myapps/app1/⁠) and has supporting R files in an app.R / server.R, ⁠global.R, and ⁠./R' subfolder that you need to access in your tests.

Choosing which function to use

• local_app_support(): For R packages or when you want automatic cleanup. The support environment is attached for the duration of the current environment, then automatically removed. This prevents pollution of the testing environment across multiple tests that test multiple apps.

• with_app_support(): Similar to local_app_support(), but uses an explicit code block. The support environment is only available within the provided expression and is cleaned up immediately after.

• load_app_support(): For standalone Shiny apps (non-package). Loads support files into the testing environment permanently with no automatic cleanup. Best used in setup-shinytest2.R for non-package apps.

Benefits

• Isolation: local_app_support() and with_app_support() prevent helper functions from one app test from interfering with another.

• Access to app internals: Test helper functions, modules, and utilities defined in your app's ./R folder without manually sourcing files.

• Package testing: Enables testing apps within packages where the app's support files are separate from the package's exported functions.

Examples

## Not run: 
# Example 1: Basic usage with local_app_support()
# File structure:
#   ./tests/testthat/apps/myapp/R/utils.R  (contains: n <- 42)
#   ./tests/testthat/test-utils.R

test_that("Can access support environment", {
  expect_false(exists("n"))
  shinytest2::local_app_support(test_path("apps/myapp"))
  expect_equal(n, 42)
})
# After test completes, n is automatically removed

# Example 2: Using with_app_support() for explicit scoping
test_that("Can access support environment", {
  expect_false(exists("n"))
  shinytest2::with_app_support(test_path("apps/myapp"), {
    expect_equal(n, 42)
  })
  expect_false(exists("n"))  # n is no longer available
})

# Example 3: Testing an app with its support files
# File structure:
#   ./inst/myapps/app1/app.R
#   ./inst/myapps/app1/R/modules.R  (contains: my_module_ui <- function() {...})
#   ./tests/testthat/test-app1.R

test_that("app1 loads with module support", {
  expect_false(exists("my_module_ui"))

  app_dir <- system.file("myapps/app1", package = "mypkg")
  local_app_support(app_dir)

  # Now we can access module functions from app1/R/
  expect_true(exists("my_module_ui"))

  # And test the app
  app <- AppDriver$new(app_dir)
  app$expect_values()
})

## End(Not run)

shinytest2 documentation built on Feb. 26, 2026, 1:06 a.m.