Add quarto_available() function for TRUE / FALSE check of quarto being found

Author: cderv

DESCRIPTION

@@ -1,6 +1,6 @@
 Package: quarto
 Title: R Interface to 'Quarto' Markdown Publishing System
-Version: 1.4.4.9008
+Version: 1.4.4.9010
 Authors@R: c(
     person("JJ", "Allaire", , "[email protected]", role = "aut",
            comment = c(ORCID = "0000-0003-0174-9868")),

NEWS.md

@@ -1,5 +1,7 @@
 # quarto (development version)
 
+- Add `quarto_available()` function to check if Quarto CLI is found (thanks, @hadley, #187).
+
 - Add several new wrapper function (thanks, @parmsam, #192): 
   - `quarto_list_extensions()` to list installed extensions using `quarto list extensions`
   - `quarto_remove_extension()` to remove an installed extension using `quarto remove extensions`

R/quarto.R

@@ -52,6 +52,70 @@ quarto_version <- function() {
   as.numeric_version(system2(quarto_bin, "--version", stdout = TRUE))
 }
 
+
+#' Check if quarto is available and version meet some requirements
+#'
+#' This function allows to test if Quarto is available and meets version requirement, a min, max or
+#' in between requirement.
+#'
+#' If `min` and `max` are provided, this will check if Quarto version is
+#' in-between two versions. If non is provided (keeping the default `NULL` for
+#' both), it will just check for Quarto availability version and return `FALSE` if not found.
+#'
+#' @param min Minimum version expected.
+#' @param max Maximum version expected
+#' @param error If `TRUE`, will throw an error if Quarto is not available or does not meet the requirement. Default is `FALSE`.
+#'
+#' @return logical. `TRUE` if requirement is met, `FALSE` otherwise.
+#'
+#' @examples
+#' # Is there an active version available ?
+#' quarto_available()
+#' # check for a minimum requirement
+#' quarto_available(min = "1.5")
+#' # check for a maximum version
+#' quarto_available(max = "1.6")
+#' # only returns TRUE if Pandoc version is between two bounds
+#' quarto_available(min = "1.4", max = "1.6")
+#'
+#' @export
+quarto_available <- function(min = NULL, max = NULL, error = FALSE) {
+  found <- FALSE
+  is_above <- is_below <- TRUE
+  if (!is.null(min) && !is.null(max)) {
+    if (min > max) {
+      cli::cli_abort(c(
+        "Minimum version {.strong {min}} cannot be greater than maximum version {.strong {max}}."
+      ))
+    }
+  }
+  quarto_version <- tryCatch(
+    quarto_version(),
+    error = function(e) NULL
+  )
+  if (!is.null(quarto_version)) {
+    if (!is.null(min)) is_above <- quarto_version >= min
+    if (!is.null(max)) is_below <- quarto_version <= max
+    found <- is_above && is_below
+  }
+  if (!found && error) {
+    cli::cli_abort(c(
+      if (is.null(min) && is.null(max)) {
+        "Quarto is not available."
+      } else {
+        "Quarto version requirement not met."
+      },
+      "*" = if (!is_above) {
+        paste0(" Minimum version expected is ", min, ".")
+      },
+      "*" = if (!is_below) {
+        paste0(" Maximum version expected is ", max, ".")
+      }
+    ))
+  }
+  return(found)
+}
+
 #' @importFrom processx run
 quarto_run <- function(
   args = character(),

tests/testthat/test-quarto.R

@@ -122,3 +122,37 @@ test_that("quarto.quiet options controls echo and overwrite function argument",
     expect_output(quarto_render(qmd, quiet = TRUE))
   })
 })
+
+test_that("quarto_available()", {
+  expect_error(
+    quarto_available("1.5", "1.4"),
+    regexp = "Minimum version .* cannot be greater than maximum version .*"
+  )
+
+  # Mock no quarto found
+  with_mocked_bindings(
+    quarto_version = function(...) NULL,
+    {
+      expect_false(quarto_available())
+      expect_error(quarto_available(error = TRUE))
+    }
+  )
+
+  local_mocked_bindings(
+    quarto_version = function(...) as.numeric_version("1.8.4")
+  )
+
+  expect_true(quarto_available())
+  expect_true(quarto_available("1", "2"))
+  expect_false(quarto_available(max = "1.5"))
+  expect_error(
+    quarto_available(max = "1.6", error = TRUE),
+    regexp = "Maximum version expected is 1.6"
+  )
+  expect_true(quarto_available(min = "1.8.4"))
+  expect_false(quarto_available(min = "1.9.5"))
+  expect_error(
+    quarto_available(min = "1.9.5", error = TRUE),
+    regexp = "Minimum version expected is 1.9.5"
+  )
+})