Correctly handle callback for unparseable code

R/eval.R

@@ -58,7 +58,7 @@ evaluate <- function(input,
 
   parsed <- parse_all(input, filename, stop_on_error != 2L)
   if (inherits(err <- attr(parsed, 'PARSE_ERROR'), 'error')) {
-    source <- new_source(parsed$src, call[[1]], output_handler$source)
+    source <- new_source(parsed$src, expression(), output_handler$source)
     output_handler$error(err)
     err$call <- NULL  # the call is unlikely to be useful
     return(list(source, err))

R/output.R

@@ -61,7 +61,9 @@ render <- function(x) if (isS4(x)) methods::show(x) else print(x)
 #'
 #' @param source Function to handle the echoed source code under evaluation.
 #'  This function should take two arguments (`src` and `call`), and return
-#'  an object that will be inserted into the evaluate outputs. 
+#'  an object that will be inserted into the evaluate outputs. `src` is the
+#'  unparsed text of the source code, and `call` is the parsed language object 
+#'  If `src` is unparsable, `call` will be `expression()`.
 #' 
 #'  Return `src` for the default evaluate behaviour. Return `NULL` to 
 #'  drop the source from the output.

tests/testthat/test-eval.R

@@ -59,3 +59,19 @@ test_that("can conditionally omit output with output handler", {
   expect_length(out, 2)
   expect_snapshot(replay(out))
 })
+
+test_that("source handled called correctly when src is unparseable", {
+  src <- NULL
+  call <- NULL
+  capture_args <- function(src, call) {
+    src <<- src
+    call <<- call
+
+    src
+  }
+  handler <- new_output_handler(source = capture_args)
+
+  evaluate("x + ", output_handler = handler)
+  expect_equal(src, new_source("x + "))
+  expect_equal(call, expression())
+})