Ensure apt update works on final images

tests/base/06-test-apt-repositories.sh

@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+
+set -e
+set -u
+set -o pipefail
+
+CWD="$(cd -P -- "$(dirname -- "$0")" && pwd -P)"
+
+IMAGE="${1}"
+VERSION="${2}"
+FLAVOUR="${3}"
+
+# shellcheck disable=SC1090
+. "${CWD}/../.lib.sh"
+
+
+
+############################################################
+# Tests
+############################################################
+
+###
+### Ensuring 'apt update' works without any issues
+###
+did="$( docker_run "${IMAGE}:${VERSION}-${FLAVOUR}" "-e DEBUG_ENTRYPOINT=2" )"
+
+if ! docker_exec "${did}" "apt update"; then
+	docker_logs "${did}" || true
+	docker_stop "${did}" || true
+	echo "Failed"
+	exit 1
+fi
+docker_stop "${did}"