feat: Add transform= parameter to $expect_download() and $expect_values() (#403)

Author: schloerke

NEWS.md

@@ -14,6 +14,9 @@
 
 * `{shinytest2}` now imports `{cli}` and no longer imports `{crayon}` (@olivroy, #399).
 
+* Added [`{testthat}`'s snapshot file `transform=` parameter support](https://github.com/r-lib/testthat/pull/1530) to `AppDriver$expect_download()` and `AppDriver$expect_values()`. This allows for text transformations of the snapshot files before they are compared. (#403)
+
+
 # shinytest2 0.3.2
 
 ## Bug / Improvements

R/app-driver-expect-download.R

@@ -90,7 +90,8 @@ app_expect_download <- function(
   output,
   ...,
   compare = NULL,
-  name = NULL
+  name = NULL,
+  transform = NULL
 ) {
   ckm8_assert_app_driver(self, private)
   rlang::check_dots_empty()
@@ -111,6 +112,7 @@ app_expect_download <- function(
     self,
     private,
     snapshot_info$download_path,
+    transform = transform,
     compare = compare
   )
 

R/app-driver-expect-values.R

@@ -176,7 +176,8 @@ app_expect_values <- function(
   output = missing_arg(),
   export = missing_arg(),
   name = NULL,
-  screenshot_args = missing_arg()
+  screenshot_args = missing_arg(),
+  transform = NULL
 ) {
   ckm8_assert_app_driver(self, private)
   rlang::check_dots_empty()
@@ -271,6 +272,7 @@ app_expect_values <- function(
     self,
     private,
     json_path,
+    transform = transform,
     compare = testthat::compare_file_text
   )
 

R/app-driver.R

@@ -147,8 +147,11 @@ check_cran_deprecated <- function(
 #'   Defaults to the resolved `timeout` value during the `AppDriver` initialization.
 #' @param timeout_ Amount of time to wait before giving up (milliseconds).
 #'   Defaults to the resolved `timeout` value during the `AppDriver` initialization.
+#' @param transform Optionally, a function to scrub sensitive or stochastic text
+#'   from the output. Should take a character vector of lines as input and
+#'   return a modified character vector as output.
 #' @param cran Deprecated. With `AppDriver` never testing on CRAN,
-#'             this parameter no longer has any effect.
+#'   this parameter no longer has any effect.
 #' @param wait_ Wait until all reactive updates have completed?
 #' @param hash_images If `TRUE`, images will be hashed before being returned.
 #'   Otherwise, all images will return their full data64 encoded value.
@@ -571,6 +574,7 @@ AppDriver <- R6Class(
       export = missing_arg(),
       screenshot_args = missing_arg(),
       name = NULL,
+      transform = transform,
       cran = deprecated()
     ) {
       check_cran_deprecated(cran)
@@ -584,6 +588,7 @@ AppDriver <- R6Class(
         export = export,
         screenshot_args = screenshot_args,
         name = name,
+        transform = transform
       )
     },
     #' @description
@@ -750,6 +755,7 @@ AppDriver <- R6Class(
       ...,
       compare = NULL,
       name = NULL,
+      transform = NULL,
       cran = deprecated()
     ) {
       check_cran_deprecated(cran)
@@ -760,6 +766,7 @@ AppDriver <- R6Class(
         output = output,
         ...,
         compare = compare,
+        transform = transform,
         name = name
       )
     },

R/expect-snapshot.R

@@ -21,6 +21,7 @@ app__expect_snapshot_file <- function(
   file,
   variant,
   name = fs::path_file(file),
+  transform = NULL,
   compare = testthat::compare_file_binary
 ) {
   ckm8_assert_app_driver(self, private)
@@ -43,6 +44,7 @@ app__expect_snapshot_file <- function(
       name = name_safe,
       cran = FALSE,
       compare = compare,
+      transform = transform,
       variant = self$get_variant()
     ),
     expectation_failure = function(cnd) {

man/AppDriver.Rd

@@ -0,0 +1,4 @@
+# transform can be passed to expect_snapshot_file()
+
+    "download-button.txt"
+

tests/testthat/_snaps/app-expect-file-transform.md

@@ -0,0 +1 @@
+Download content!

tests/testthat/_snaps/app-expect-file-transform/001-download-button.txt

@@ -0,0 +1,11 @@
+{
+  "input": {
+
+  },
+  "output": {
+    "txt": "(app loaded)"
+  },
+  "export": {
+
+  }
+}