Require explicit data setup option

data-setup/run_data_setup.sh

@@ -1,14 +1,32 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
-MODE="${1:---dry-run}"
+usage() {
+  cat >&2 <<'EOF'
+Usage: bash data-setup/run_data_setup.sh <option>
+
+Options:
+  --dry-run        check setup scripts only
+  --download-only  download source files where scriptable
+  --build-test     rebuild inputs from existing local sources
+  --compare        compare regenerated inputs with committed data/
+  --full-test      download, rebuild, and compare locally
+EOF
+}
+
+if [ "$#" -ne 1 ]; then
+  usage
+  exit 1
+fi
+
+MODE="$1"
 repo_root="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd -P)"
 cd "$repo_root"
 
 case "$MODE" in
   --dry-run|--download-only|--build-test|--compare|--full-test) ;;
   *)
-    echo "Usage: $0 [--dry-run|--download-only|--build-test|--compare|--full-test]" >&2
+    usage
     exit 1
     ;;
 esac