.travis.yml in method-not-implemented-1.0.0 vs .travis.yml in method-not-implemented-1.0.1

- old
+ new

@@ -1,6 +1,22 @@
 language: ruby
 
 rvm:
-  - 2.4.0
+  - 2.0
+  - 2.1
+  - 2.2
+  - 2.3
+  - 2.4
 
 cache: bundler
+
+env:
+  - RAKE_ENV=test BUNDLE_PATH=vendor/bundle
+
+before_install:
+  - gem install bundler
+
+install:
+  - bundle install
+
+script:
+  - bundle exec rake test