add generic test verifier and use it instead of hard coding test ever…

…ywhere

lib/sprinkle/verifiers/directory.rb

@@ -9,7 +9,7 @@ module Directory
 
       # Tests that the directory <tt>dir</tt> exists.
       def has_directory(dir)
-        @commands << "test -d #{dir}"
+        test "-d #{dir}"
       end
     end
   end

lib/sprinkle/verifiers/executable.rb

@@ -26,7 +26,7 @@ def has_executable(path)
         # Be smart: If the path includes a forward slash, we're checking
         # an absolute path. Otherwise, we're checking a global executable
         if path.include?('/')
-          @commands << "test -x #{path}"
+          test "-x #{path}"
         else
           @commands << "[ -n \"`echo \\`which #{path}\\``\" ]"
         end

lib/sprinkle/verifiers/file.rb

@@ -15,11 +15,15 @@ module File
 
       # Checks to make sure <tt>path</tt> is a file on the remote server.
       def has_file(path)
-        @commands << "test -f #{path}"
+        test "-f #{path}"
       end
 
       def no_file(path)
-        @commands << "test ! -f #{path}"
+        test "! -f #{path}"
+      end
+
+      def md5_of_file(path, md5)
+        test "`md5sum #{path} | cut -f1 -d' '` == \"#{md5}\""
       end
 
       def file_contains(path, text)

lib/sprinkle/verifiers/symlink.rb

@@ -20,9 +20,9 @@ module Symlink
       # given, it checks that <tt>symlink</tt> points to <tt>file</tt>
       def has_symlink(symlink, file = nil)
         if file.nil?
-          @commands << "test -L #{symlink}"
+          test "-L #{symlink}"
         else
-          @commands << "test '#{file}' = `readlink #{symlink}`"
+          test "'#{file}' = `readlink #{symlink}`"
         end
       end
     end