add a lint script to verify that Ginkgo is not imported

.travis/no_ginkgo.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+# Verify that no non-test files import Ginkgo or Gomega.
+
+set -e
+
+HAS_TESTING=false
+
+cd ..
+for f in $(find . -name "*.go" ! -name "*_test.go"); do
+	if grep -q "github.com/onsi/ginkgo" $f; then
+    echo "$f imports github.com/onsi/ginkgo"
+    HAS_TESTING=true
+	fi
+	if grep -q "github.com/onsi/gomega" $f; then
+    echo "$f imports github.com/onsi/gomega"
+    HAS_TESTING=true
+	fi
+done
+
+if "$HAS_TESTING"; then
+	exit 1
+fi
+exit 0

.travis/script.sh

@@ -3,6 +3,7 @@
 set -ex
 
 if [ ${TESTMODE} == "lint" ]; then
+  .travis/no_ginkgo.sh
   ./bin/golangci-lint run ./...
 fi