add script to validate nothing was changed that needed to re-run go generate

Signed-off-by: Jessica Frazelle <acidburn@docker.com>

scripts/validate-html-generation

@@ -0,0 +1,28 @@
+#!/bin/bash
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+source "${DIR}/.validate"
+
+IFS=$'\n'
+files=( $(validate_diff --diff-filter=ACMR --name-only -- 'static/index.html' || true) )
+unset IFS
+
+if [ ${#files[@]} -gt 0 ]; then
+	# We run go generate to and see if we have a diff afterwards
+	go generate >/dev/null
+	# Let see if the working directory is clean
+	diffs="$(git status --porcelain -- static.go 2>/dev/null)"
+	if [ "$diffs" ]; then
+		{
+			echo 'The result of go generate differs'
+			echo
+			echo "$diffs"
+			echo
+			echo 'Please re-run go generate'
+			echo
+		} >&2
+		false
+	else
+		echo 'Congratulations! File generation is done correctly.'
+	fi
+fi