Return component ONCE slots with handler resolution

scripts/run_cli_tests.sh

@@ -69,6 +69,7 @@ if [[ "$action" == "run" ]]; then
 	scripts/test_dependency_invalidation.sh
 	scripts/test_cold_component_deadline.sh
 	scripts/test_nested_component_props.sh
+	scripts/test_component_once_prefetch.sh
 	scripts/test_relative_component_cache.sh
 	scripts/test_password_hashing.sh
 	scripts/test_mysql_epoch_refresh.sh

scripts/test_component_once_prefetch.sh

@@ -0,0 +1,39 @@
+#!/usr/bin/env bash
+set -euo pipefail
+cd "$(dirname "$0")/.."
+
+test_name="component-once-prefetch-test-$$"
+site_directory="${UCE_TEST_SITE_DIRECTORY:-site}"
+if [[ -z "${UCE_TEST_SITE_DIRECTORY:-}" && -r /etc/uce/settings.cfg ]]; then
+	configured_site_directory=$(awk -F= '/^[[:space:]]*SITE_DIRECTORY[[:space:]]*=/ {gsub(/^[[:space:]]+|[[:space:]]+$/, "", $2); print $2; exit}' /etc/uce/settings.cfg)
+	if [[ -n "${configured_site_directory:-}" ]]; then
+		site_directory="$configured_site_directory"
+	fi
+fi
+source_dir="$site_directory/$test_name"
+
+cleanup() {
+	rm -rf "$source_dir"
+}
+trap cleanup EXIT
+mkdir -p "$source_dir"
+
+printf '%s\n' \
+	'CLI(Request& context) {' \
+	'  String first = component("child", context);' \
+	'  String second = component("child", context);' \
+	'  DValue perf = request_perf();' \
+	'  print(first, ",", second, ",", perf["component_resolve_count"].to_u64(), ",", perf["component_loaded_reuse_count"].to_u64());' \
+	'}' >"$source_dir/entry.uce"
+
+printf '%s\n' \
+	'ONCE(Request& context) { context.call["once"] = context.call["once"].to_u64() + 1; }' \
+	'COMPONENT(Request& context) { print(context.call["once"].to_u64()); }' >"$source_dir/child.uce"
+
+output=$(scripts/uce-cli "/$test_name/entry.uce")
+if [[ "$output" != "1,1,1,0" ]]; then
+	echo "component ONCE slot was not returned with the primary handler: $output" >&2
+	exit 1
+fi
+
+echo "component ONCE prefetch passed"