make arc rest more tolerant of failures

Author: dblodgett-usgs

R/arcrest_tools.R

@@ -170,7 +170,7 @@ query_usgs_arcrest <- function(AOI = NULL,  ids = NULL,
                           outFields = "*",
                           f = "geojson")
 
-        out[[i]] <- hgf_sf(URL, body = post_body, encode = "form")
+        out[i] <- list(hgf_sf(URL, body = post_body, encode = "form"))
       }
 
       if(inherits(out[[1]], "data.frame")) {

tests/testthat/test_arcrest.R

@@ -66,3 +66,31 @@ test_that("basic 3dhp service requests", {
     expect_s3_class(test_data, "sf")
   })
 })
+
+test_that("query_usgs_arcrest degrades gracefully when the feature fetch fails", {
+
+  AOI_new <- sf::st_as_sfc(sf::st_bbox(c(xmin = -89.5, ymin = 43.0,
+                                     xmax = -89.4, ymax = 43.1),
+                                   crs = "+proj=longlat +datum=WGS84 +no_defs"))
+
+  # fully mocked at the internal-helper level (no fixtures/network) so a
+  # fresh, never-memoised call signature isn't required
+  testthat::local_mocked_bindings(
+    get_arcrest_service_info = function(...) list(
+      url_base = "https://example.com/MapServer/",
+      all_layers = list(layers = list(list(id = 0, name = "Flowline",
+                                           type = "Feature Layer"))),
+      id = "id3dhp"),
+    hgf_json = function(...) list(objectIds = list(1, 2, 3)),
+    # simulates the feature-fetch request failing (e.g. an HTTP 504) after
+    # the objectIds lookup already succeeded
+    hgf_sf = function(...) NULL,
+    .package = "hydrogeofetch")
+
+  expect_warning(
+    out <- hydrogeofetch:::query_usgs_arcrest(
+      AOI_new, service = "3DHP_all", type = "flowline"),
+    "features found")
+
+  expect_null(out)
+})