ExtUtils::Installed's files method expects you to pass it the "main" module of a dist. For Catalyst, this is Catalyst::Runtime.

$ perl -MExtUtils::Installed -le 'print for ExtUtils::Installed->new->
+files("Catalyst::Runtime")'
.../bin/catalyst.pl
.../lib/perl5/Catalyst/Exception/Detach.pm
.../lib/perl5/Catalyst/Script/CGI.pm
.../lib/perl5/Catalyst/Exception/Basic.pm
.../lib/perl5/Catalyst/Base.pm
.../lib/perl5/Catalyst/ActionContainer.pm
.../lib/perl5/Catalyst/Test.pm
.../lib/perl5/Catalyst/PSGI.pod
.../lib/perl5/Catalyst/ActionChain.pm
.../lib/perl5/Catalyst/Delta.pod
.../lib/perl5/Catalyst/Component.pm
.../lib/perl5/Catalyst.pm
.../lib/perl5/Catalyst/Stats.pm
.../lib/perl5/Catalyst/Component/ApplicationAttribute.pm
.../lib/perl5/Catalyst/Engine.pm
.../lib/perl5/Catalyst/Exception.pm
.../lib/perl5/Catalyst/Dispatcher.pm
.../lib/perl5/Catalyst/Runtime.pm
.../lib/perl5/Catalyst/DispatchType.pm
.../lib/perl5/Catalyst/Contributing.pod
.../lib/perl5/Catalyst/Controller.pm
.../lib/perl5/Catalyst/ActionRole/QueryMatching.pm
.../lib/perl5/Catalyst/Script/Test.pm
.../lib/perl5/Catalyst/UTF8.pod
.../lib/perl5/Catalyst/Engine/HTTP.pm
.../lib/perl5/Catalyst/ActionRole/ConsumesContent.pm
.../lib/perl5/Catalyst/Script/FastCGI.pm
.../lib/perl5/Catalyst/ActionRole/Scheme.pm
.../lib/perl5/Catalyst/RouteMatching.pod
.../lib/perl5/Catalyst/Response/Writer.pm
.../lib/perl5/Catalyst/EngineLoader.pm
.../lib/perl5/Catalyst/Script/Server.pm
.../lib/perl5/Catalyst/Script/Create.pm
.../lib/perl5/Catalyst/DispatchType/Index.pm
.../lib/perl5/Catalyst/Request/Upload.pm
.../lib/perl5/Catalyst/ActionRole/HTTPMethods.pm
.../lib/perl5/Catalyst/Action.pm
.../lib/perl5/Catalyst/DispatchType/Path.pm
.../lib/perl5/Catalyst/DispatchType/Default.pm
.../lib/perl5/Catalyst/Model.pm
.../lib/perl5/Catalyst/Exception/Go.pm
.../lib/perl5/Catalyst/Middleware/Stash.pm
.../lib/perl5/Catalyst/Response.pm
.../lib/perl5/Catalyst/ScriptRole.pm
.../lib/perl5/Catalyst/View.pm
.../lib/perl5/Catalyst/Component/ContextClosure.pm
.../lib/perl5/Catalyst/Exception/Interface.pm
.../lib/perl5/Catalyst/DispatchType/Chained.pm
.../lib/perl5/Catalyst/Upgrading.pod
.../lib/perl5/Catalyst/Utils.pm
.../lib/perl5/Catalyst/Log.pm
.../lib/perl5/Catalyst/Request/PartData.pm
.../lib/perl5/Catalyst/ScriptRunner.pm
.../lib/perl5/Catalyst/Plugin/Unicode/Encoding.pm
.../lib/perl5/Catalyst/Request.pm
.../lib/perl5/Catalyst/ClassData.pm
[download]