Add git diff check to travis

.travis.yml

@@ -6,6 +6,10 @@ node_js:
   - "lts/*"
   - "9"
   - "10"
+matrix:
+  include:
+    - node_js: "lts/*"
+      env: TEST_SUITE=gitdiff:ci
 env:
   - TEST_SUITE=test
 script: npm run-script $TEST_SUITE

package.json

@@ -10,6 +10,7 @@
     "coverage": "nyc --branches 100 --functions 100 --check-coverage npm run unit",
     "format": "npm run prettier -- --write",
     "format:ci": "npm run prettier -- --check",
+    "gitdiff:ci": "npm run build && git diff --exit-code",
     "lint": "tslint -p tsconfig.json -c tslint.json",
     "prettier": "prettier 'ts_src/**/*.ts' --ignore-path ./.prettierignore",
     "test": "npm run build && npm run format:ci && npm run lint && npm run unit",