Added Worker#shell_run method.

lib/queue_stick/worker.rb

@@ -1,5 +1,7 @@
 module QueueStick
   class Worker
+    class ShellCommandError < StandardError; end
+
     # TODO(dbalatero): configurable?
     MAX_ERRORS = 5
 
@@ -22,6 +24,24 @@ def get_message_from_queue
     def delete_message_from_queue(message)
       raise NotImplementedError, "#delete_message_from_queue needs to be implemented in a subclass."
     end
+
+    # This method will run a shell command, and return the
+    # output of the command's run.
+    #
+    # It will loudly raise an error if the shell command fails,
+    # which, if raised in your process() method, will be 
+    # guaranteed to hit your recover() method.
+    def shell_run(cmd)
+      result = `#{cmd}`
+      process_status = $?
+
+      if !process_status.success?
+        # TODO(dbalatero): get the stderr output.
+        raise ShellCommandError, "Error running shell command: #{cmd}"
+      end
+
+      result
+    end
 
     def run_loop
       # Exit the run loop if we get a shutdown request.

spec/queue_stick/worker_spec.rb

@@ -10,6 +10,30 @@
     end
   end
 
+  describe "shell_run" do
+    before(:all) do
+      @worker = QueueStick::Worker.new
+    end
+
+    it "should raise an error if a process fails" do
+      lambda {
+        @worker.shell_run("ls -l /fds8aufj92njkdsajfdslafjdsafdsa 2>/dev/null")
+      }.should raise_error(QueueStick::Worker::ShellCommandError)
+    end
+
+    it "should not raise an error if a process doesn't fail" do
+      lambda {
+        @worker.shell_run("ls -l /")
+      }.should_not raise_error
+    end
+
+    it "should return its output" do
+      result = @worker.shell_run("ls -l /")
+      result.should_not be_empty
+      result.should =~ /bin/  # is this a bad assumption?
+    end
+  end
+
   describe "run_loop" do
     class RunLoopTestWorker < QueueStick::Worker
     end