start a lint script

.travis.yml

@@ -2,4 +2,5 @@ language: go
 go:
 - 1.11.1
 script:
+- ./script/lint
 - go test -v ./...

script/lint

@@ -0,0 +1,5 @@
+#!/bin/bash -ex
+
+# Ensure the repository is clean after code generation.
+./script/generate
+test -z "$(git status --porcelain)"