feat: add Go example (#10)

Author: alexeagle

MODULE.bazel

@@ -50,3 +50,5 @@ pip.parse(
     requirements_lock = "//examples/lang_toolchains:requirements.txt",
 )
 use_repo(pip, "pypi")
+
+bazel_dep(name = "rules_go", version = "0.48.0")

examples/BUILD

@@ -1,5 +1,6 @@
 load("@rules_proto//proto:defs.bzl", "proto_library")
 load("@rules_python//python:proto.bzl", "py_proto_library")
+load("@rules_go//proto:def.bzl", "go_proto_library")
 
 package(default_visibility = ["//visibility:public"])
 
@@ -18,3 +19,9 @@ java_proto_library(
     name = "foo_java_proto",
     deps = [":foo_proto"],
 )
+
+go_proto_library(
+    name = "foo_go_proto",
+    importpath = "example.com/foo_proto",
+    proto = ":foo_proto",
+)

examples/foo.proto

@@ -2,6 +2,7 @@ syntax = "proto3";
 
 import "google/protobuf/any.proto";
 
+option go_package = "example.com/foo_proto";
 option java_package = "proto";
 
 message Foo {

examples/go/BUILD

@@ -0,0 +1,7 @@
+load("@rules_go//go:def.bzl", "go_test")
+
+go_test(
+    name = "foo_proto_test",
+    srcs = ["foo_proto_test.go"],
+    deps = ["//examples:foo_go_proto"],
+)

examples/go/foo_proto_test.go

@@ -0,0 +1,16 @@
+package proto_test
+
+import (
+	"testing"
+
+	"example.com/foo_proto"
+)
+
+func TestFoo(t *testing.T) {
+	msg := &foo_proto.Foo{
+		Msg: "hello world",
+	}
+	if msg.Msg != "hello world" {
+		t.Fail()
+	}
+}