Change message load_timeout (#394)

Co-authored-by: Garrick Aden-Buie <[email protected]>

NEWS.md

@@ -4,6 +4,8 @@
 
 * Add support for `$click()`ing `{bslib}`'s `input_task_button()` (#829).
 
+* Improved the error message when an app takes too long to start up (@LouisLeNezet, #394).
+
 # shinytest2 0.3.2
 
 ## Bug / Improvements

R/app-driver-start.R

@@ -97,8 +97,15 @@ app_start_shiny <- function(
     Sys.sleep(0.2)
 
     if (i == max_i) {
-      app_abort(self, private, paste0(
-        "Cannot find shiny port number. Error lines found:\n",
+      app_abort(self, private, sprintf(
+        paste(
+          "The Shiny app failed to start up within %s second%s.",
+          "To increase the loading timeout, consult the documentation in `?AppDriver`",
+          "for the `load_timeout` argument of `AppDriver$new()`.",
+          "The app printed the following lines to stderr during start up:\n%s"
+        ),
+        load_timeout / 1000,
+        if (load_timeout == 1000) "" else "s",
         paste(err_lines, collapse = "\n")
       ))
     }