Travis: Add 2.4.0, use jruby-9.1.7.0; don't trap QUIT on JRuby since it's not supported

.travis.yml

@@ -3,11 +3,12 @@ cache: bundler
 before_install: gem i bundler
 matrix:
   include:
+    - rvm: 2.4.0
     - rvm: 2.3.3
     - rvm: 2.2
     - rvm: 2.1
     - rvm: 2.0
-    - rvm: jruby-9.1.6.0
+    - rvm: jruby-9.1.7.0
       jdk: oraclejdk8
       env:
         - JRUBY_OPTS='--debug'

lib/hutch/waiter.rb

@@ -12,7 +12,9 @@ class ContinueProcessingSignals < RuntimeError
     end
 
     def self.supported_signals_of(list)
-      list.keep_if { |s| Signal.list.keys.include? s }
+      list.keep_if { |s| Signal.list.keys.include?(s) }.tap do |result|
+        result.delete('QUIT') if defined?(JRUBY_VERSION)
+      end
     end
 
     SHUTDOWN_SIGNALS = supported_signals_of(%w(QUIT TERM INT)).freeze

spec/hutch/waiter_spec.rb

@@ -12,25 +12,39 @@ def start_kill_thread(signal)
       end
     end
 
-    described_class::SHUTDOWN_SIGNALS.each do |signal|
-      # JRuby does not support QUIT:
-      # The signal QUIT is in use by the JVM and will not work correctly on this platform
-      next if signal == 'QUIT' && defined?(JRUBY_VERSION)
-
-      context "a #{signal} signal is received" do
-        it "logs that hutch is stopping" do
-          expect(Hutch::Logging.logger).to receive(:info)
-            .with("caught SIG#{signal}, stopping hutch...")
-
-          start_kill_thread(signal)
-          described_class.wait_until_signaled
-        end
+    context 'a QUIT signal is received', if: RSpec::Support::Ruby.mri? do
+      it 'logs that hutch is stopping' do
+        expect(Hutch::Logging.logger).to receive(:info)
+          .with('caught SIGQUIT, stopping hutch...')
+
+        start_kill_thread('QUIT')
+        described_class.wait_until_signaled
+      end
+    end
+
+    context 'a TERM signal is received' do
+      it 'logs that hutch is stopping' do
+        expect(Hutch::Logging.logger).to receive(:info)
+          .with('caught SIGTERM, stopping hutch...')
+
+        start_kill_thread('TERM')
+        described_class.wait_until_signaled
+      end
+    end
+
+    context 'a INT signal is received' do
+      it 'logs that hutch is stopping' do
+        expect(Hutch::Logging.logger).to receive(:info)
+          .with('caught SIGINT, stopping hutch...')
+
+        start_kill_thread('INT')
+        described_class.wait_until_signaled
       end
     end
   end
 
   describe described_class::SHUTDOWN_SIGNALS do
-    it "includes only things in Signal.list.keys" do
+    it 'includes only things in Signal.list.keys' do
       expect(described_class).to eq(described_class & Signal.list.keys)
     end
   end