[Travis] Only run on OS X for the examples

.travis.yml

-osx_image: xcode7.3
-language: objective-c
 cache: bundler
+
+matrix:
+  include:
+  - rvm: system
+    env: COCOAPODS_CI_TASKS=EXAMPLES
+    osx_image: xcode7.3
+    language: objective-c
+  - rvm: 2.3.1
+    env: COCOAPODS_CI_TASKS=LINT
+    git:
+      submodules: false
+
 rvm:
   # OS X 10.9.5-10.10.0 (2.0.0-p481)
-  - system
+  - 2.0.0-p481
   # OS X 10.9.3-10.9.4
   - 2.0.0-p451
   # OS X 10.9.0-10.9.2
@@ -11,6 +21,9 @@ rvm:
   # - 2.0.0-p247
   - 2.3.1
 
+env:
+  - COCOAPODS_CI_TASKS=SPECS
+
 branches:
   only:
     - master
@@ -19,16 +32,15 @@ branches:
 before_install:
   # There is a bug in travis. When using system ruby, bundler is not
   # installed and causes the default install action to fail.
-  - sudo gem install bundler
+  - if [ "$TRAVIS_RUBY_VERSION" = "system" ]; then sudo gem install "bundler:~> 1.13"; else gem install "bundler:~> 1.13"; fi
   # RubyGems 2.0.14 isn't a fun time on 2.0.0p648
-  - if [ "$(ruby -v | cut -d ' ' -f2)" = "2.0.0p648" ]; then sudo gem update --system; fi
+  - if [ "$TRAVIS_RUBY_VERSION" = "system" ]; then sudo gem update --system; fi
 
 before_script:
-  - bundle exec pod repo update --silent
   - bundle exec pod env
 
 script:
-  - bundle exec rake
+  - bundle exec rake spec:all
   - bundle exec danger
 
 addons:

Rakefile

@@ -136,25 +136,40 @@ begin
     # to be run separately.
     #
     task :all => 'fixture_tarballs:unpack' do
+      tasks = ENV.fetch('COCOAPODS_CI_TASKS') { 'ALL' }.upcase.split(/\s+/)
+      if %w(ALL SPECS EXAMPLES LINT).&(tasks).empty?
+        raise "Unknown tasks #{tasks} -- supported options for COCOAPODS_CI_TASKS are " \
+              'ALL, SPECS, EXAMPLES, LINT'
+      end
+      specs = %w(ALL SPECS).&(tasks).any?
+      examples = %w(ALL EXAMPLES).&(tasks).any?
+      lint = %w(ALL LINT).&(tasks).any?
+
       # Forcing colored to be included on String before Term::ANSIColor, so that Inch will work correctly.
       require 'colored'
       ENV['GENERATE_COVERAGE'] = 'true'
       puts "\033[0;32mUsing #{`ruby --version`}\033[0m"
 
-      title 'Running the specs'
-      sh "bundle exec bacon #{specs('**/*')}"
+      if specs
+        title 'Running the specs'
+        sh "bundle exec bacon #{specs('**/*')}"
 
-      title 'Running Integration tests'
-      sh 'bundle exec bacon spec/integration.rb'
+        title 'Running Integration tests'
+        sh 'bundle exec bacon spec/integration.rb'
+      end
 
-      title 'Running examples'
-      Rake::Task['examples:build'].invoke
+      if examples
+        title 'Running examples'
+        Rake::Task['examples:build'].invoke
+      end
 
-      title 'Running RuboCop'
-      Rake::Task['rubocop'].invoke
+      if lint
+        title 'Running RuboCop'
+        Rake::Task['rubocop'].invoke
 
-      title 'Running Inch'
-      Rake::Task['inch'].invoke
+        title 'Running Inch'
+        Rake::Task['inch'].invoke
+      end
     end
 
     namespace :fixture_tarballs do