Allow package tests to fail gracefully when internet resources are unavailable

tests/testthat/helper.R

@@ -1,29 +1,32 @@
 download_nc_basic <- function() {
+  # online source
+  file_url <- "nc_basic_spm_grass7.zip"
+  base_url <- "https://grass.osgeo.org/sampledata"
+  path_url <- "north_carolina"
+  url <- paste(base_url, path_url, file_url, sep = "/")
+
+  # local file path for download
   tmpdir <- tempdir()
+  zip_path <- file.path(tmpdir, file_url)
 
-  if (!file.exists(file.path(tmpdir, "nc_basic_spm_grass7.zip"))) {
-    base_url <- "https://grass.osgeo.org/sampledata"
-    path_url <- "north_carolina"
-    file_url <- "nc_basic_spm_grass7.zip"
-
-    download.file(
-      paste(base_url, path_url, file_url, sep = "/"),
-      file.path(tmpdir, "nc_basic_spm_grass7.zip")
-    )
-
-    unzip(
-      file.path(tmpdir, "nc_basic_spm_grass7.zip"),
-      exdir = file.path(tmpdir, "grassdb")
-    )
-    unlink(file.path(tmpdir, "nc_basic_spm_grass7.zip"))
-  }
+  # extraction directory
+  db_dir <- file.path(tmpdir, "grassdb")
+
+  if (!file.exists(zip_path)) {
+    result <- try({
+      suppressWarnings(download.file(url, zip_path, quiet = TRUE))
+    }, silent = TRUE)
 
-  dataset <- list(
-    gisDbase = file.path(tmpdir, "grassdb"),
-    location = "nc_basic_spm_grass7"
-  )
+    if (inherits(result, "try-error")) {
+      message("Failed to download GRASS GIS example dataset")
+      return(NULL)
+    }
+
+    unzip(zip_path, exdir = db_dir)
+    unlink(zip_path)
+  }
 
-  return(dataset)
+  return(list(gisDbase = db_dir, location = "nc_basic_spm_grass7"))
 }
 
 get_gisbase <- function() {

tests/testthat/test-execGRASS.R

@@ -3,6 +3,7 @@ library(terra)
 
 test_that("testing basic doGRASS, execGRASS, stringexecGRASS", {
   skip_if_not(!is.null(gisBase), "GRASS GIS not found on PATH")
+  skip_if(is.null(testdata), "GRASS GIS example dataset is not available")
 
   loc <- initGRASS(
     home = tempdir(),
@@ -88,6 +89,7 @@ test_that("testing basic doGRASS, execGRASS, stringexecGRASS", {
 
 test_that("testing options doGRASS, execGRASS, stringexecGRASS", {
   skip_if_not(!is.null(gisBase), "GRASS GIS not found on PATH")
+  skip_if(is.null(testdata), "GRASS GIS example dataset is not available")
 
   loc <- initGRASS(
     home = tempdir(),

tests/testthat/test-gmeta.R

@@ -3,6 +3,7 @@ library(terra)
 
 testthat::test_that("testing gmeta", {
   skip_if_not(!is.null(gisBase), "GRASS GIS not found on PATH")
+  skip_if(is.null(testdata), "GRASS GIS example dataset is not available")
 
   # Initialize a temporary GRASS project using the example data
   loc <- initGRASS(