[Outdated] Friendly error when no podspec present for external source deps

lib/cocoapods/command/outdated.rb

@@ -52,6 +52,7 @@ module Pod
 
       def updates
         @updates ||= begin
+          ensure_external_podspecs_present!
           spec_sets.map do |set|
             spec = set.specification
             source_version = set.versions.first
@@ -111,6 +112,17 @@ module Pod
           config.lockfile
         end
       end
+
+      def ensure_external_podspecs_present!
+        return unless config.podfile
+        config.podfile.dependencies.each do |dep|
+          next if dep.external_source.nil?
+          unless config.sandbox.specification(dep.root_name)
+            raise Informative, 'You must run `pod install` first to ensure that the ' \
+              "podspec for `#{dep.root_name}` has been fetched."
+          end
+        end
+      end
     end
   end
 end

spec/functional/command/outdated_spec.rb

@@ -78,5 +78,18 @@ module Pod
       SourcesManager.expects(:update).never
       run_command('outdated', '--no-repo-update')
     end
+
+    it 'tells the user to run `pod install` when external sources need to be fetched' do
+      lockfile = mock('Lockfile')
+      lockfile.stubs(:version).returns(Version.new('1.0'))
+      lockfile.stubs(:pod_names).returns(%w(AFNetworking))
+      config.stubs(:lockfile).returns(lockfile)
+      podfile = Podfile.new do
+        pod 'AFNetworking', :git => 'https://github.com/AFNetworking/AFNetworking.git'
+      end
+      config.stubs(:podfile).returns(podfile)
+      exception = lambda { run_command('outdated', '--no-repo-update') }.should.raise Informative
+      exception.message.should.include 'You must run `pod install` first to ensure that the podspec for `AFNetworking` has been fetched.'
+    end
   end
 end