fix test error

Author: Yunuuuu

R/guides-.R

@@ -509,7 +509,6 @@ Guides <- ggproto(
     ) %||% valid.just(calc_element("legend.justification.inside", theme))
     inside_positions <- vector("list", length(positions))
 
-    # we'll merge inside legends with same coordinate into same guide box
     # we grouped the legends by the positions, for inside legends, they'll be
     # splitted by the actual inside coordinate
     groups <- positions
@@ -556,9 +555,14 @@ Guides <- ggproto(
   },
 
   # Render the guides into grobs
-  draw = function(self, theme, positions, direction = NULL,
+  draw = function(self, theme, positions = NULL, direction = NULL,
                   params = self$params,
                   guides = self$guides) {
+    positions <- positions %||% vapply(
+      params,
+      function(p) p$position[1] %||% "right",
+      character(1), USE.NAMES = FALSE
+    )
     if (is.null(direction)) {
       directions <- ifelse(
         positions %in% c("top", "bottom"), 

tests/testthat/test-guides.R

@@ -156,10 +156,10 @@ test_that("empty guides are dropped", {
   expect_equal(nrow(gd), 0)
 
   # Draw guides
-  guides <- p$plot$guides$draw(theme_gray(), direction = "vertical")
+  guides <- p$plot$guides$assemble(theme_gray())
 
   # All guide-boxes should be empty
-  expect_equal(lengths(guides, use.names = FALSE), rep(0, 4))
+  expect_true(is.zero(guides))
 })
 
 test_that("bins can be parsed by guides for all scale types", {