add common unit test

Dockerfile

@@ -0,0 +1,12 @@
+FROM golang:1-alpine as builder
+WORKDIR /data
+COPY . .
+RUN apk add --no-cache build-base make && \
+  make test && \
+  make
+
+FROM alpine:latest
+WORKDIR /data
+COPY ./config/config.yml .
+COPY --from=builder /data/tcp-proxy /usr/bin/tcp-proxy
+CMD ["/usr/bin/tcp-proxy"]