Date break doc improvement (#5080)

* Document valid specifications of date_breaks

* date_breaks() to `breaks_width()`

* Don't use `date_breaks()` in tests

Author: teunbrand

R/scale-date.r

@@ -15,10 +15,13 @@
 #'   - A function that takes the limits as input and returns breaks as output
 #' @param date_breaks A string giving the distance between breaks like "2
 #'   weeks", or "10 years". If both `breaks` and `date_breaks` are
-#'   specified, `date_breaks` wins.
+#'   specified, `date_breaks` wins. Valid specifications are 'sec', 'min',
+#'   'hour', 'day', 'week', 'month' or 'year', optionally followed by 's'.
 #' @param date_minor_breaks A string giving the distance between minor breaks
 #'   like "2 weeks", or "10 years". If both `minor_breaks` and
-#'   `date_minor_breaks` are specified, `date_minor_breaks` wins.
+#'   `date_minor_breaks` are specified, `date_minor_breaks` wins. Valid
+#'   specifications are 'sec', 'min', 'hour', 'day', 'week', 'month' or 'year',
+#'   optionally followed by 's'.
 #' @param minor_breaks One of:
 #'   - `NULL` for no breaks
 #'   - `waiver()` for the breaks specified by `date_minor_breaks`
@@ -282,14 +285,14 @@ datetime_scale <- function(aesthetics, trans, palette,
 
 
   # Backward compatibility
-  if (is.character(breaks)) breaks <- date_breaks(breaks)
-  if (is.character(minor_breaks)) minor_breaks <- date_breaks(minor_breaks)
+  if (is.character(breaks)) breaks <- breaks_width(breaks)
+  if (is.character(minor_breaks)) minor_breaks <- breaks_width(minor_breaks)
 
   if (!is.waive(date_breaks)) {
-    breaks <- date_breaks(date_breaks)
+    breaks <- breaks_width(date_breaks)
   }
   if (!is.waive(date_minor_breaks)) {
-    minor_breaks <- date_breaks(date_minor_breaks)
+    minor_breaks <- breaks_width(date_minor_breaks)
   }
   if (!is.waive(date_labels)) {
     labels <- function(self, x) {

man/scale_date.Rd

@@ -16,8 +16,8 @@ test_that("date scale draws correctly", {
   expect_doppelganger("dates along x, default breaks",
     dt
   )
-  expect_doppelganger("scale_x_date(breaks = date_breaks(\"2 weeks\"))",
-    dt + scale_x_date(breaks = date_breaks("2 weeks"))
+  expect_doppelganger("scale_x_date(breaks = breaks_width(\"2 weeks\"))",
+    dt + scale_x_date(breaks = breaks_width("2 weeks"))
   )
   expect_doppelganger("scale_x_date(breaks = \"3 weeks\")",
     dt + scale_x_date(date_breaks = "3 weeks")
@@ -31,8 +31,8 @@ test_that("date scale draws correctly", {
 
   dt <- ggplot(df, aes(price, dx)) + geom_line()
   expect_doppelganger("dates along y, default breaks", dt)
-  expect_doppelganger("scale_y_date(breaks = date_breaks(\"2 weeks\"))",
-    dt + scale_y_date(breaks = date_breaks("2 weeks"))
+  expect_doppelganger("scale_y_date(breaks = breaks_width(\"2 weeks\"))",
+    dt + scale_y_date(breaks = breaks_width("2 weeks"))
   )
   expect_doppelganger("scale_y_date(breaks = \"3 weeks\")",
     dt + scale_y_date(date_breaks = "3 weeks")