prevent failures when caching non-existing rhsm_identity

Author: vchepkov

lib/facter/rhsm_identity.rb

@@ -29,7 +29,7 @@ module Facter::Util::RhsmIdentity
   module_function
 
   def rhsm_identity
-    value = nil
+    value = ''
     begin
       output = Facter::Core::Execution.execute(
         '/usr/sbin/subscription-manager identity',

spec/facter/util/rhsm_identity_spec.rb

@@ -46,17 +46,17 @@
   end
   it 'returns the nothing for no data' do
     expect(Facter::Core::Execution).to receive(:execute).and_return('')
-    expect(Facter::Util::RhsmIdentity.rhsm_identity).to eq(nil)
+    expect(Facter::Util::RhsmIdentity.rhsm_identity).to eq('')
   end
   it 'returns the nothing for no command' do
     expect(Facter::Core::Execution).to receive(:execute).and_return(nil)
-    expect(Facter::Util::RhsmIdentity.rhsm_identity).to eq(nil)
+    expect(Facter::Util::RhsmIdentity.rhsm_identity).to eq('')
   end
   it 'returns the nothing for an error' do
     expect(Facter::Core::Execution).to receive(:execute) {
       throw Facter::Core::Execution::ExecutionFailure
     }
     expect(Facter).to receive(:debug)
-    expect(Facter::Util::RhsmIdentity.rhsm_identity).to eq(nil)
+    expect(Facter::Util::RhsmIdentity.rhsm_identity).to eq('')
   end
 end