Catch uncommitted build output automatically in Travis

Connects-To: #573
Change-Type: patch

.travis.yml

@@ -7,7 +7,7 @@ matrix:
     - CAN_DEPLOY=true
 before_install:
 - npm -g install npm
-script: echo 'TODO Write some tests'
+script: ./automation/catch-uncommitted-output
 notifications:
   email: false
 deploy:

automation/catch-uncommitted-output

@@ -0,0 +1,15 @@
+#!/bin/sh
+
+npm run build
+
+if ! git diff HEAD --exit-code ; then
+	echo '\n** Uncommitted changes found after build - FAIL **'
+	exit 1
+elif test -n "$(git ls-files --exclude-standard --others)" ; then
+	echo '\n** Untracked uncommitted files found after build: **'
+	git ls-files --exclude-standard --others
+	echo '** FAIL **'
+	exit 2
+else
+	echo '\nNo unexpected changes after build, all good.'
+fi