Add support for function type in TealAppDriver$new(app)

NEWS.md

@@ -3,6 +3,7 @@
 ### Enhancements
 
 * Exported `select_decorators()` to help module developers resolve the decorators applied to a specific output (#1733).
+* Add support for function argument in `TealAppDriver$new(app)`.
 
 ### Bug fixes
 

R/TealAppDriver.R

@@ -25,7 +25,12 @@ TealAppDriver <- R6::R6Class( # nolint: object_name.
     #' @description
     #' Initialize a `TealAppDriver` object for testing a `teal` application.
     #'
-    #' @param app (`teal_app`)
+    #' @param app (`teal_app` or `function`) The `teal` application to be tested.
+    #' This value can be 2 different things:
+    #' - A `teal_app` object, which is the result of calling `teal::init()`.
+    #' - A function that returns a `teal_app` object.
+    #'
+    #' Other values that [`shinytest2::AppDriver`] `new()` functions accepts are not yet supported.
     #' @param options (`list`) passed to `shinyApp(options)`. See [shiny::shinyApp()].
     #' @param timeout (`numeric`) Default number of milliseconds for any timeout or
     #' timeout_ parameter in the `TealAppDriver` class.
@@ -51,7 +56,12 @@ TealAppDriver <- R6::R6Class( # nolint: object_name.
                           timeout = rlang::missing_arg(),
                           load_timeout = rlang::missing_arg(),
                           ...) {
-      checkmate::assert_class(app, "teal_app")
+      checkmate::assert(
+        combine = "or",
+        .var.name = "app",
+        checkmate::check_function(app),
+        checkmate::check_class(app, "teal_app")
+      )
       checkmate::assert_list(teal_options, names = "named")
       # Default timeout is hardcoded to 4s in shinytest2:::resolve_timeout
       # New default is set with environment variables if not already set by user
@@ -61,28 +71,21 @@ TealAppDriver <- R6::R6Class( # nolint: object_name.
         extra_envvar$SHINYTEST2_TIMEOUT <- "20000"
       }
       if (Sys.getenv("SHINYTEST2_LOAD_TIMEOUT") == "") {
-        extra_envvar$SHINYTEST2_TIMEOUT <- "100000"
-      }
-
-      if (length(teal_options)) {
-        orig_server <- app$server
-        opts <- teal_options
-        app$server <- function(input, output, session) {
-          do.call(base::options, opts)
-          orig_server(input, output, session)
-        }
+        extra_envvar$SHINYTEST2_LOAD_TIMEOUT <- "100000"
       }
 
       rlang::check_installed("withr")
       suppressWarnings(
         withr::with_envvar(
           new = extra_envvar,
           code = super$initialize(
-            shiny::shinyApp(ui = app$ui, server = app$server, options = options),
+            if (is.function(app)) app else shiny::shinyApp(ui = app$ui, server = app$server),
             name = "teal",
             variant = shinytest2::platform_variant(),
             timeout = timeout,
-            load_timeout = load_timeout
+            load_timeout = load_timeout,
+            shiny_args = options,
+            options = teal_options
           )
         )
       )
@@ -128,7 +131,7 @@ TealAppDriver <- R6::R6Class( # nolint: object_name.
       super$stop(...)
     },
     #' @description
-    #' Append parent [`shinytest2::AppDriver`] `click` method with a call to `waif_for_idle()` method.
+    #' Append parent [`shinytest2::AppDriver`] `click` method with a call to `wait_for_idle()` method.
     #' @param ... arguments passed to parent [`shinytest2::AppDriver`] `click()` method.
     click = function(...) {
       super$click(...)