switch to using a gemfile and calling via bundle

Gemfile

@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+source 'https://rubygems.org'
+
+gem 'cocoapods', '1.2.0'
+gem 'xcpretty'

Gemfile.lock

@@ -0,0 +1,77 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    CFPropertyList (2.3.5)
+    activesupport (4.2.8)
+      i18n (~> 0.7)
+      minitest (~> 5.1)
+      thread_safe (~> 0.3, >= 0.3.4)
+      tzinfo (~> 1.1)
+    claide (1.0.1)
+    cocoapods (1.2.0)
+      activesupport (>= 4.0.2, < 5)
+      claide (>= 1.0.1, < 2.0)
+      cocoapods-core (= 1.2.0)
+      cocoapods-deintegrate (>= 1.0.1, < 2.0)
+      cocoapods-downloader (>= 1.1.3, < 2.0)
+      cocoapods-plugins (>= 1.0.0, < 2.0)
+      cocoapods-search (>= 1.0.0, < 2.0)
+      cocoapods-stats (>= 1.0.0, < 2.0)
+      cocoapods-trunk (>= 1.1.2, < 2.0)
+      cocoapods-try (>= 1.1.0, < 2.0)
+      colored (~> 1.2)
+      escape (~> 0.0.4)
+      fourflusher (~> 2.0.1)
+      gh_inspector (~> 1.0)
+      molinillo (~> 0.5.5)
+      nap (~> 1.0)
+      ruby-macho (~> 0.2.5)
+      xcodeproj (>= 1.4.1, < 2.0)
+    cocoapods-core (1.2.0)
+      activesupport (>= 4.0.2, < 5)
+      fuzzy_match (~> 2.0.4)
+      nap (~> 1.0)
+    cocoapods-deintegrate (1.0.1)
+    cocoapods-downloader (1.1.3)
+    cocoapods-plugins (1.0.0)
+      nap
+    cocoapods-search (1.0.0)
+    cocoapods-stats (1.0.0)
+    cocoapods-trunk (1.1.2)
+      nap (>= 0.8, < 2.0)
+      netrc (= 0.7.8)
+    cocoapods-try (1.1.0)
+    colored (1.2)
+    escape (0.0.4)
+    fourflusher (2.0.1)
+    fuzzy_match (2.0.4)
+    gh_inspector (1.0.3)
+    i18n (0.8.1)
+    minitest (5.10.1)
+    molinillo (0.5.6)
+    nanaimo (0.2.3)
+    nap (1.1.0)
+    netrc (0.7.8)
+    rouge (1.11.1)
+    ruby-macho (0.2.6)
+    thread_safe (0.3.6)
+    tzinfo (1.2.2)
+      thread_safe (~> 0.1)
+    xcodeproj (1.4.2)
+      CFPropertyList (~> 2.3.3)
+      activesupport (>= 3)
+      claide (>= 1.0.1, < 2.0)
+      colored (~> 1.2)
+      nanaimo (~> 0.2.3)
+    xcpretty (0.2.4)
+      rouge (~> 1.8)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  cocoapods (= 1.2.0)
+  xcpretty
+
+BUNDLED WITH
+   1.13.7

circle.yml

@@ -3,8 +3,7 @@ machine:
     version: 8.2
 
 dependencies:
-  pre:
-    - gem install xcpretty --no-rdoc --no-ri --no-document --quiet
+  post:
     - rake lint:install
     - curl -sS https://cocoapods-specs.circleci.com/fetch-cocoapods-repo-from-s3.sh | bash
 

rakelib/pod.rake

@@ -2,6 +2,6 @@ namespace :pod do
   desc 'Lint the Pod'
   task :lint do |task|
     Utils.print_info 'Linting the pod spec'
-    Utils.run(%Q(pod lib lint "#{POD_NAME}.podspec" --quick), task)
+    Utils.run(%Q(bundle exec pod lib lint "#{POD_NAME}.podspec" --quick), task)
   end
 end

rakelib/utils.rake

@@ -29,9 +29,9 @@ class Utils
     command = [*cmd].join(' && ')
 
     if ENV['CI']
-      Rake.sh "set -o pipefail && (#{command}) | tee \"#{ENV['CIRCLE_ARTIFACTS']}/#{name}_raw.log\" | xcpretty --color --report junit --output \"#{ENV['CIRCLE_TEST_REPORTS']}/xcode/#{name}.xml\""
+      Rake.sh "set -o pipefail && (#{command}) | tee \"#{ENV['CIRCLE_ARTIFACTS']}/#{name}_raw.log\" | bundle exec xcpretty --color --report junit --output \"#{ENV['CIRCLE_TEST_REPORTS']}/xcode/#{name}.xml\""
     elsif system('which xcpretty > /dev/null')
-      Rake.sh "set -o pipefail && (#{command}) | xcpretty -c"
+      Rake.sh "set -o pipefail && (#{command}) | bundle exec xcpretty -c"
     else
       Rake.sh command
     end