travis: log detailed test output on failure
diff --git a/.travis.yml b/.travis.yml
index f2a7dbc..1a8415b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -35,4 +35,7 @@
   - ./travis/scancode.sh
 
 script:
-  - npm test -- -v
+  - npm test
+
+after_failure:
+  - cat build/mocha.test.log