Describes defaults in usage text

scripts/test/fixture.sh

 #!/bin/bash
 
+repo_root="/vagrant"
+config_file="rspec.json"
+
 usage() {
     echo "Usage: $0 create|start|stop|destroy [-f config_file] [-r repo_root] [-c container_name|all]" 1>&2
+    echo "    -f defaults to '${config_file}'" 1>&2
+    echo "    -r defaults to '${repo_root}'" 1>&2
+    echo "    -c must be specified, use 'all' for all" 1>&2
     exit 1
 }
 
@@ -154,9 +160,6 @@ if [ $# -gt 1 ]; then
     OPTIND=$((OPTIND+1))
 fi
 
-repo_root="/vagrant"
-config_file="rspec.json"
-
 # collect the optional arguments
 while getopts "hf:r:c:" opt; do
   case $opt in