Command now implements an ICommand interface.

src/Cully/ICommand.php

@@ -0,0 +1,53 @@
+<?php
+
+namespace Cully;
+
+interface ICommand {
+    /**
+     * @return bool
+     */
+    public function hasRun();
+    /**
+     * Whether the last command succeeded.  Will return FALSE if no
+     * command has been executed (we haven't succeeded because we
+     * haven't tried).
+     *
+     * A successful command is one that has an exit code of 0.
+     *
+     * @return bool
+     */
+    public function success();
+    /**
+     * Whether the last command failed.  This will return FALSE if no
+     * command has been executed (we haven't failed because we haven't
+     * tried).
+     *
+     * @return bool
+     */
+    public function failure();
+    /**
+     * The last command executed.
+     *
+     * @return string
+     */
+    public function getCommand();
+    /**
+     * Will be null if a command hasn't been executed, or if the
+     * last executed command didn't return an exit code.
+     *
+     * @return int|null
+     */
+    public function getExitStatus();
+    /**
+     * Standard output from command.
+     *
+     * @return string
+     */
+    public function getOutput();
+    /**
+     * Standard error from the command.
+     *
+     * @return string
+     */
+    public function getError();
+}

src/Cully/Local/Command.php

@@ -2,7 +2,9 @@
 
 namespace Cully\Local;
 
-class Command {
+use Cully\ICommand;
+
+class Command implements ICommand {
     /**
      * @var string
      */