avoid including fragile grobName in snapshot

Author: teunbrand

tests/testthat/_snaps/theme-elements.md

@@ -64,10 +64,8 @@
 ---
 
     Code
-      element_grob(el, label = element_blank())
+      x <- element_grob(el, label = element_blank())
     Condition
       Warning:
       `label` cannot be a <ggplot2::element_blank> object.
-    Output
-      zeroGrob[NULL] 
 

tests/testthat/test-theme-elements.R

@@ -100,7 +100,7 @@ test_that("element_text throws appropriate conditions", {
   # labs(y = element_blank()) for some reason
   el <- theme_get()$text
   expect_snapshot(
-    element_grob(el, label = element_blank())
+    x <- element_grob(el, label = element_blank())
   )
 })