Add a new "test" Makefile target

Dockerfile.build

@@ -5,6 +5,6 @@ RUN apt-get update && apt-get install -y make nasm && rm -rf /var/lib/apt/lists/
 WORKDIR /usr/src/hello
 COPY . /usr/src/hello
 
-RUN make clean hello
+RUN make clean hello test
 
 CMD ["./hello"]

Makefile

@@ -5,3 +5,7 @@ hello: hello.asm
 .PHONY: clean
 clean:
 	-rm -vf hello
+
+.PHONY: test
+test: hello
+	./hello