bugfix: handle empty processes result

lib/resources/processes.rb

@@ -31,6 +31,7 @@ class Processes < Inspec.resource(1)
     # get all running processes
     cmd = inspec.command('ps aux')
     all = cmd.stdout.split("\n")[1..-1]
+    return [] if all.nil?
 
     lines = all.map do |line|
       # user   32296  0.0  0.0  42592  7972 pts/15   Ss+  Apr06   0:00 zsh

test/unit/resources/processes_test.rb

@@ -6,6 +6,11 @@ require 'helper'
 require 'inspec/resource'
 
 describe 'Inspec::Resources::Processes' do
+  it 'handles empty process results' do
+    resource = load_resource('processes', 'nothing')
+    _(resource.list).must_equal []
+  end
+
   it 'verify processes resource' do
     resource = load_resource('processes', '/bin/bash')
     _(resource.list).must_equal [{