add check_continuous_limits()

Author: teunbrand

R/scale-.R

@@ -128,12 +128,14 @@ continuous_scale <- function(aesthetics, scale_name = deprecated(), palette, nam
   }
 
   transform <- as.transform(transform)
+  limits   <- allow_lambda(limits)
+
   if (!is.null(limits) && !is.function(limits)) {
     limits <- transform$transform(limits)
   }
+  check_continuous_limits(limits, call = call)
 
   # Convert formula to function if appropriate
-  limits   <- allow_lambda(limits)
   breaks   <- allow_lambda(breaks)
   labels   <- allow_lambda(labels)
   rescaler <- allow_lambda(rescaler)
@@ -1402,6 +1404,16 @@ check_transformation <- function(x, transformed, name, arg = NULL, call = NULL)
   cli::cli_warn(msg, call = call)
 }
 
+check_continuous_limits <- function(limits, ...,
+                                    arg = caller_arg(limits),
+                                    call = caller_env()) {
+  if (is.null(limits) || is.function(limits)) {
+    return(invisible())
+  }
+  check_numeric(limits, arg = arg, call = call, allow_na = TRUE)
+  check_length(limits, 2L, arg = arg, call = call)
+}
+
 trans_support_nbreaks <- function(trans) {
   "n" %in% names(formals(trans$breaks))
 }

tests/testthat/test-scales-breaks-labels.R

@@ -79,7 +79,7 @@ test_that("out-of-range breaks are dropped", {
 
 test_that("no minor breaks when only one break", {
   sc1 <- scale_x_discrete(limits = "a")
-  sc2 <- scale_x_continuous(limits = 1)
+  sc2 <- scale_x_continuous(limits = c(1, 1))
 
   expect_length(sc1$get_breaks_minor(), 0)
   expect_length(sc2$get_breaks_minor(), 0)