I added a Makefile at the repo root with build, test and run targets. build is the default goal, all three are declared .PHONY, and the recipes are tab-indented. run runs cargo run -- $(ARGS), so you can pass arguments with make run ARGS="--shout Ada".
I ran make build, make test and make run ARGS=Ada. All three passed, and the run printed Hi, Ada!. I didn't try --shout or any other flags through ARGS.
No other files changed, so this shouldn't conflict with the open pull requests. I didn't open any issues or comment on other pull requests.