fix linux user spec

Author: h00die

lib/msf/core/post/linux/user.rb

@@ -4,6 +4,7 @@ module Msf
   class Post
     module Linux
       module User
+        include ::Msf::Post::Common
         #
         # Returns a string of the user's home directory
         #

spec/lib/msf/core/post/linux/user_spec.rb

@@ -13,22 +13,22 @@
 
     context 'when the user exists' do
       it 'returns the home directory path from /etc/passwd' do
-        expect(tester).to receive(:cmd_exec)
+        expect(subject).to receive(:cmd_exec)
           .with(expected_command)
           .and_return("/home/testuser\n")
 
-        result = tester.get_home_dir(user)
+        result = subject.get_home_dir(user)
         expect(result).to eq('/home/testuser')
       end
     end
 
     context 'when the user does not exist in /etc/passwd' do
       it 'returns an empty string' do
-        expect(tester).to receive(:cmd_exec)
+        expect(subject).to receive(:cmd_exec)
           .with(expected_command)
           .and_return("\n")
 
-        result = tester.get_home_dir(user)
+        result = subject.get_home_dir(user)
         expect(result).to eq('')
       end
     end