Add before run method (#33)

* Updated example

Ref #30

* Add before run method

* Add unit test to before function and remove job instance parameter

README.md

@@ -285,14 +285,15 @@ For example you might want to add an entry to you logs, ping a url etc...
 By default, the job will be forced to run in foreground (because the output is injected to the function), if you don't need the output, you can pass `true` as a second parameter to allow the execution in background (in this case `$output` will be empty).
 
 ```php
+// $logger and $messenger here are your own implementation
 $scheduler->php('script.php')->then(function ($output) use ($logger, $messenger) {
     $logger->info($output);
 
     $messenger->ping('myurl.com', $output);
 });
 
-$scheduler->php('script.php')->then(function ($output) {
-    log('Job executed!');
+$scheduler->php('script.php')->then(function ($output) use ($logger) {
+    $logger->info('Job executed!');
 }, true);
 ```
 

src/GO/Job.php

@@ -109,6 +109,13 @@ class Job
      */
     private $emailConfig = [];
 
+    /**
+     * A function to execute before the job is executed.
+     *
+     * @var callable
+     */
+    private $before;
+
     /**
      * A function to execute after the job is executed.
      *
@@ -365,6 +372,10 @@ public function run()
         // Write lock file if necessary
         $this->createLockFile();
 
+        if (is_callable($this->before)) {
+            call_user_func($this->before);
+        }
+
         if (is_callable($compiled)) {
             $this->output = $this->exec($compiled);
         } else {
@@ -519,6 +530,20 @@ private function emailOutput()
         return true;
     }
 
+    /**
+     * Set function to be called before job execution
+     * Job object is injected as a parameter to callable function.
+     *
+     * @param callable $fn
+     * @return self
+     */
+    public function before(callable $fn)
+    {
+        $this->before = $fn;
+
+        return $this;
+    }
+
     /**
      * Set a function to be called after job execution.
      * By default this will force the job to run in foreground

tests/GO/JobTest.php

@@ -353,6 +353,24 @@ public function testShouldReturnOutputOfJobExecution()
         $this->assertEquals(['hi'], $job3->getOutput());
     }
 
+    public function testShouldRunCallbackBeforeJobExecution()
+    {
+        $job = new Job(function () {
+            return 'Job for testing before function';
+        });
+
+        $callbackWasExecuted = false;
+        $outputWasSet = false;
+
+        $job->before(function () use ($job, &$callbackWasExecuted, &$outputWasSet) {
+            $callbackWasExecuted = true;
+            $outputWasSet = ! is_null($job->getOutput());
+        })->run();
+
+        $this->assertTrue($callbackWasExecuted);
+        $this->assertFalse($outputWasSet);
+    }
+
     public function testShouldRunCallbackAfterJobExecution()
     {
         $job = new Job(function () {