CocoaPodsでアプリ側ターゲットのbuild_settingsを変更する方法 ref: http://qiita.com/roothybrid7/items/403b2fb453b1674102a4

file0.txt

#ifndef APP_TESTING
    // テスト以外のときだけ実行する処理
    // 広告SDKとかが勝手にブラウザへ飛ばす処理とか
#endif

Podfile

TESTING_TARGETS = %w[AppTests AppIntegrationTests]
post_install do |installer|
  # アプリ側のxcode projectを開く
  Xcodeproj::Project.open('App.xcodeproj').tap do |project|
    targets = project.targets.find_all do |target|
      TESTING_TARGETS.include?(target.name)
    end
    # Test用macro定義
    targets.each do |target|
      target.build_configurations.each do |config|
        if config.name == "Debug"
          preprocessor_definitions = config.build_settings['GCC_PREPROCESSOR_DEFINITIONS'] || ['$(inherited)']
          preprocessor_definitions = [preprocessor_definitions] unless preprocessor_definitions.instance_of?(Array)
          preprocessor_definitions.push('APP_TESTING=1').uniq!

          config.build_settings['GCC_PREPROCESSOR_DEFINITIONS'] = preprocessor_definitions
        end
      end
    end

    project.save
  end
end