Add changelog

This is useful so that the script can be sourced without exiting the calling subshell.

changelog.d/19209.misc

@@ -0,0 +1 @@
+Refactor `scripts-dev/complement.sh` logic to avoid `exit` to facilitate being able to source it from other scripts (composable).

scripts-dev/complement.sh

@@ -72,6 +72,7 @@ For help on arguments to 'go test', run 'go help testflag'.
 EOF
 }
 
+main() {
   # parse our arguments
   skip_docker_build=""
   skip_complement_run=""
@@ -80,7 +81,7 @@ while [ $# -ge 1 ]; do
     case "$arg" in
       "-h")
         usage
-            exit 1
+        return 1
         ;;
       "-f"|"--fast")
         skip_docker_build=1
@@ -207,7 +208,7 @@ fi
 
   if [ -n "$skip_complement_run" ]; then
       echo "Skipping Complement run as requested."
-    exit
+      return 0
   fi
 
   export COMPLEMENT_BASE_IMAGE=complement-synapse
@@ -299,3 +300,12 @@ echo "Images built; running complement with ${extra_test_args[@]} $@ ${test_pack
   cd "$COMPLEMENT_DIR"
 
   go test -v -tags "synapse_blacklist" -count=1 "${extra_test_args[@]}" "$@" "${test_packages[@]}"
+}
+
+main "$@"
+# For any non-zero exit code (indicating some sort of error happened), we want to exit
+# with that code.
+exit_code=$?
+if [ $exit_code -ne 0 ]; then
+    exit $exit_code
+fi