Better handling of errors that aren't JSON

Author: wch

NEWS.md

@@ -1,5 +1,6 @@
 # 1.0.5.9000
 
+* Better display of error messages.
 
 # 1.0.5
 

R/errors.R

@@ -6,7 +6,15 @@ report_error <- function(response) {
     invisible(response)
   } else {
     call <- sys.call(-1)
-    stop(create_condition(response, "error", call = call))
+
+    cond <- create_condition(response, "error", call = call)
+
+    # Sometimes the message from create_condition can be very long, but it is
+    # necessary to show the whole thing so that the user can understand it.
+    old_options <- options(warning.length = nchar(cond$message))
+    on.exit(options(old_options))
+
+    stop(cond)
   }
 }
 
@@ -18,24 +26,34 @@ create_condition <- function(response,
 
   class <- match.arg(class)
 
-  cont <- content(response)
+  cont <- content(response, as = "text")
+
+  message <- NULL
+  status <- NULL
 
-  if (is.character(cont)) {
-    # In rare cases the error content is just a string. This can happen, for
-    # example, when there is a problem loading execute_script.js.
-    # https://github.com/rstudio/shinytest/issues/165
+  if (jsonlite::validate(cont)) {
+    try({
+      # This can error if `cont` doesn't include the fields we want.
+      json <- fromJSON(
+        cont[["value"]][["message"]],
+        simplifyVector = FALSE
+      )
+      message <- json[["errorMessage"]] %||% "WebDriver error"
+      status <- cont$status
+    })
+  }
+
+  # We can end up in this block if:
+  # * The error content is just a string, or raw HTML. This can happen, for
+  #   example, when there is a problem loading execute_script.js.
+  #   https://github.com/rstudio/shinytest/issues/165
+  #   https://github.com/rstudio/shinytest/issues/190
+  # * The `cont` object was JSON, but did not include the needed fields.
+  if (is.null(status)) {
     message <- cont
     # Need to manually set status code for UnknownError. From:
     # https://github.com/detro/ghostdriver/blob/873c9d6/src/errors.js#L135
     status <- 13L
-
-    } else {
-    json <- fromJSON(
-      cont[["value"]][["message"]],
-      simplifyVector = FALSE
-    )
-    message <- json[["errorMessage"]] %||% "WebDriver error"
-    status <- cont$status
   }