Add a --build-only argument to complement.sh

scripts-dev/complement.sh

@@ -47,12 +47,16 @@ Run the complement test suite on Synapse.
   -f    Skip rebuilding the docker images, and just use the most recent
         'complement-synapse:latest' image
 
+  --build-only
+        Only build the Docker images. Don't actually run Complement.
+
 For help on arguments to 'go test', run 'go help testflag'.
 EOF
 }
 
 # parse our arguments
 skip_docker_build=""
+skip_complement_run=""
 while [ $# -ge 1 ]; do
     arg=$1
     case "$arg" in
@@ -63,6 +67,9 @@ while [ $# -ge 1 ]; do
         "-f")
             skip_docker_build=1
             ;;
+        "--build-only")
+            skip_complement_run=1
+            ;;
         *)
             # unknown arg: presumably an argument to gotest. break the loop.
             break
@@ -106,6 +113,11 @@ if [ -z "$skip_docker_build" ]; then
     echo_if_github "::endgroup::"
 fi
 
+if [ -n "$skip_complement_run" ]; then
+    echo "Skipping Complement run as requested."
+    exit
+fi
+
 export COMPLEMENT_BASE_IMAGE=complement-synapse
 
 extra_test_args=()