Merge pull request #104 from sfgeorge/patch-1

[CI] Add CI builds against C-Ruby 2.4, 2.5 and 2.6

Author: bklang

.travis.yml

@@ -1,6 +1,10 @@
+dist: xenial
 language: ruby
 rvm:
-  - 2.3.0
+  - 2.3.8
+  - 2.4.5
+  - 2.5.3
+  - 2.6.3
   - jruby-19mode
   - rbx-19mode
   - ruby-head
@@ -11,6 +15,6 @@ matrix:
     - rvm: ruby-head
 notifications:
   irc: "irc.freenode.org#adhearsion"
-sudo: true
 before_install:
+  - rvm list
   - sudo apt-get install libpcap-dev -y

spec/sippy_cup/runner_spec.rb

@@ -534,7 +534,7 @@ def active_thread_count
         end
 
         it "proxies stderr to the terminal" do
-          expect(capture(:stderr) { subject.run }.strip).to eq(error_string)
+          expect(capture(:stderr) { subject.run }.strip).to include(error_string)
         end
 
         it "does not leak threads" do