modify test file and enable GO111MODULE

Change commands ran and their order in ./scripts/test to prevent source
code from dependencies being pulled in on each build, while still
verifying required dependencies. Also enable
GO111MODULE in the Dockerfile to allow use of modules while in the
$GOPATH.

Author: Jusshersmith

Dockerfile

@@ -7,6 +7,7 @@ FROM golang:1.11 AS build
 
 ENV GOFLAGS='-ldflags=-s -ldflags=-w'
 ENV CGO_ENABLED=0
+ENV GO111MODULE=on
 
 WORKDIR /go/src/github.com/buzzfeed/sso
 

scripts/test

@@ -11,18 +11,20 @@ if [ -n "$res" ]; then
   exit 1
 fi
 
-git diff --exit-code 
-if [ "$?" -gt "0" ]; then
-  exit 1
-fi
+# where necessary attempts to add/remove modules from go.mod and go.sum.
+echo "running go mod tidy ..."
+go mod tidy
 
-echo "running go mod vendor ..."
-go mod vendor
 git diff --exit-code
 if [ "$?" -gt "0" ]; then
   exit 1
 fi
 
+# outputs any local suspect modules and, if found will exit
+# with a non-zero status.
+echo "running go mod verify ..."
+go mod verify
+
 echo "running golint ..."
 golint -set_exit_status cmd internal