[Spec] Verify explicit `use_frameworks!` exception

lib/cocoapods/installer.rb

@@ -380,7 +380,7 @@ module Pod
           if pod_targets.any?(&:uses_swift?)
             raise Informative, 'Pods written in Swift can only be integrated as frameworks; this ' \
               'feature is still in beta. Add `use_frameworks!` to your Podfile or target to opt ' \
-              'in to using it.'
+              'into using it.'
           end
         end
       end

spec/unit/installer_spec.rb

@@ -194,6 +194,25 @@ module Pod
 
     #-------------------------------------------------------------------------#
 
+    describe '#verify_framework_usage' do
+      it 'raises when Swift pods are used without explicit `use_frameworks!`' do
+        fixture_path = ROOT + 'spec/fixtures'
+        config.repos_dir = fixture_path + 'spec-repos'
+        podfile = Pod::Podfile.new do
+          platform :ios, '8.0'
+          xcodeproj 'SampleProject/SampleProject'
+          pod 'OrangeFramework', :path => (fixture_path + 'orange-framework').to_s
+        end
+        lockfile = generate_lockfile
+        config.integrate_targets = false
+
+        @installer = Installer.new(config.sandbox, podfile, lockfile)
+        should.raise(Informative) { @installer.install! }.message.should.match /use_frameworks/
+      end
+    end
+
+    #-------------------------------------------------------------------------#
+
     describe 'Dependencies Resolution' do
       describe '#analyze' do
         it 'prints a warning if the version of the Lockfile is higher than the one of the executable' do