explicit roundtrip verification

Author: lorenzwalthert

R/transform-files.R

@@ -104,9 +104,11 @@ parse_transform_serialize <- function(text, transformers) {
   )
   serialized_transformed_text <-
     serialize_parse_data_flattened(flattened_pd, start_line = start_line)
-  verify_roundtrip(text, serialized_transformed_text, transformers)
-  serialized_transformed_text
 
+  if (can_verify_roundtrip(transformers)) {
+    verify_roundtrip(text, serialized_transformed_text)
+  }
+  serialized_transformed_text
 }
 
 #' Apply transformers to a parse table
@@ -157,40 +159,44 @@ apply_transformers <- function(pd_nested, transformers) {
 }
 
 
-#' Verify the styling if possible
+
+#' Check whether a roundtip verification can be carried out
+#'
+#' If scope was set to "line_breaks" or lower (compare [tidyverse_style()]),
+#' we can compare the expression before and after styling and return an error if
+#' it is not the same.
+#' @param transformers The list of transformer functions used for styling.
+#'   Needed for reverse engineering the scope.
+can_verify_roundtrip <- function(transformers) {
+  is.null(transformers$token)
+}
+
+#' Verify the styling
 #'
 #' If scope was set to "line_breaks" or lower (compare [tidyverse_style()]),
 #' we can compare the expression before and after styling and return an error if
 #' it is not the same. Note that this method ignores comments and no
 #' verification can be conducted if scope > "line_breaks".
 #' @param old_text The initial expression in its character representation.
 #' @param new_text The styled expression in its character representation.
-#' @param transformers The list of transformer functions used for styling.
-#'   Needed for reverse engineering the scope.
 #' @examples
-#' styler:::verify_roundtrip("a+1", "a + 1", tidyverse_style(scope = "line_breaks"))
-#' styler:::verify_roundtrip(
-#'   "a+1",
-#'   "a + 1 # comments are dropped",
-#'   tidyverse_style(scope = "line_breaks")
-#' )
+#' styler:::verify_roundtrip("a+1", "a + 1")
+#' styler:::verify_roundtrip("a+1", "a + 1 # comments are dropped")
 #' \dontrun{
-#' styler:::verify_roundtrip("a+1", "b - 3", tidyverse_style(scope = "line_breaks"))
+#' styler:::verify_roundtrip("a+1", "b - 3")
 #' }
-verify_roundtrip <- function(old_text, new_text, transformers) {
-  if (is.null(transformers$token)) {
-    expressions_are_identical <- identical(
-      parse(text = old_text, keep.source = FALSE),
-      parse(text = new_text, keep.source = FALSE)
+verify_roundtrip <- function(old_text, new_text) {
+  expressions_are_identical <- identical(
+    parse(text = old_text, keep.source = FALSE),
+    parse(text = new_text, keep.source = FALSE)
+  )
+  if (!expressions_are_identical) {
+    msg <- paste(
+      "The expression evaluated before the styling is not the same as the",
+      "expression after styling. This should not happen. Please file a",
+      "bug report on GitHub (https://github.com/r-lib/styler/issues)",
+      "using a reprex."
     )
-    if (!expressions_are_identical) {
-      msg <- paste(
-        "The expression evaluated before the styling is not the same as the",
-        "expression after styling. This should not happen. Please file a",
-        "bug report on GitHub (https://github.com/r-lib/styler/issues)",
-        "using a reprex."
-      )
-      stop(msg, call. = FALSE)
-    }
+    stop(msg, call. = FALSE)
   }
 }

man/can_verify_roundtrip.Rd

@@ -1,25 +1,17 @@
 context("roundtrip works")
 
-test_that("correct styling does not give an error for scope < tokens", {
-  expect_error(verify_roundtrip(
-    "1+1", "1 + 1", tidyverse_style(scope = "spaces")
-  ), NA)
-  expect_error(verify_roundtrip(
-    "1+1", "1 + 1", tidyverse_style(scope = "line_breaks")
-  ), NA)
-  expect_error(verify_roundtrip(
-    "1+1", "10+10", tidyverse_style(scope = "tokens")
-  ), NA)
+
+test_that("can_verify_roundtrip works", {
+  expect_true(can_verify_roundtrip(tidyverse_style(scope = "line_breaks")))
+  expect_true(can_verify_roundtrip(tidyverse_style(scope = "spaces")))
+  expect_true(can_verify_roundtrip(tidyverse_style(scope = "indention")))
+  expect_false(can_verify_roundtrip(tidyverse_style(scope = "tokens")))
+})
+
+test_that("correct styling does not give an error", {
+  expect_error(verify_roundtrip("1+1", "1 + 1"), NA)
 })
 
-test_that("incorrect styling does give an error", {
-  expect_error(verify_roundtrip(
-    "1-1", "1 + 1", tidyverse_style(scope = "spaces")
-  ), "bug")
-  expect_error(verify_roundtrip(
-    "1-1", "1 + 1", tidyverse_style(scope = "line_breaks")
-  ), "bug")
-  expect_error(verify_roundtrip(
-    "1-1", "1 + 1", tidyverse_style(scope = "tokens")
-  ), NA)
+test_that("corrupt styling does give an error", {
+  expect_error(verify_roundtrip("1-1", "1 + 1"), "bug")
 })