Adding chain able jobs.

This adds a simple mechanism to dispatch a new job if the previous job
is successful.

src/Illuminate/Bus/Queueable.php

@@ -25,6 +25,13 @@ trait Queueable
      */
     public $delay;
 
+    /**
+     * The jobs that should run if this job is successful.
+     *
+     * @var array
+     */
+    public $chained = [];
+
     /**
      * Set the desired connection for the job.
      *
@@ -63,4 +70,31 @@ public function delay($delay)
 
         return $this;
     }
+
+    /**
+     * Set the jobs that should run if this job is successful.
+     *
+     * @param  array  $chain
+     * @return $this
+     */
+    public function then($chain)
+    {
+        $this->chained = collect($chain)->map(function ($job) {
+            return serialize($job);
+        })->all();
+
+        return $this;
+    }
+
+    /**
+     * Dispatch the next job on the chain.
+     *
+     * @return void
+     */
+    public function dispatchNextJobInChain()
+    {
+        if (! empty($this->chained)) {
+            dispatch(unserialize(array_shift($this->chained))->then($this->chained));
+        }
+    }
 }

src/Illuminate/Foundation/Bus/PendingDispatch.php

@@ -54,6 +54,19 @@ public function delay($delay)
         return $this;
     }
 
+    /**
+     * Set the jobs that should run if this job is successful.
+     *
+     * @param  array  $chain
+     * @return $this
+     */
+    public function then($chain)
+    {
+        $this->job->then($chain);
+
+        return $this;
+    }
+
     /**
      * Handle the object's destruction.
      *

src/Illuminate/Queue/CallQueuedHandler.php

@@ -43,6 +43,8 @@ public function call(Job $job, array $data)
         );
 
         if (! $job->isDeletedOrReleased()) {
+            $this->ensureNextJobIsChainIsDispatched($command);
+
             $job->delete();
         }
     }
@@ -81,6 +83,19 @@ protected function setJobInstanceIfNecessary(Job $job, $instance)
         return $instance;
     }
 
+    /**
+     * Ensure the next job in the chain is dispatched if applicable.
+     *
+     * @param  mixed  $command
+     * @return void
+     */
+    protected function ensureNextJobIsChainIsDispatched($command)
+    {
+        if (method_exists($command, 'dispatchNextJobInChain')) {
+            $command->dispatchNextJobInChain();
+        }
+    }
+
     /**
      * Call the failed method on the job instance.
      *

tests/Integration/IntegrationTest.php

@@ -1,11 +1,12 @@
 <?php
 
+use Orchestra\Testbench\TestCase;
 use Illuminate\Support\Facades\Route;
 
 /**
  * @group integration
  */
-class IntegrationTest extends Orchestra\Testbench\TestCase
+class IntegrationTest extends TestCase
 {
     public function test_simple_route_through_the_framework()
     {

tests/Integration/Queue/JobChainingTest.php

@@ -0,0 +1,55 @@
+<?php
+
+use Illuminate\Bus\Queueable;
+use Orchestra\Testbench\TestCase;
+use Illuminate\Foundation\Bus\Dispatchable;
+use Illuminate\Contracts\Queue\ShouldQueue;
+
+/**
+ * @group integration
+ */
+class JobChainingTest extends TestCase
+{
+    public function tearDown()
+    {
+        JobChainingTestFirstJob::$ran = false;
+        JobChainingTestSecondJob::$ran = false;
+    }
+
+
+    public function test_jobs_can_be_chained_on_success()
+    {
+        JobChainingTestFirstJob::dispatch()->then([
+            new JobChainingTestSecondJob
+        ]);
+
+        $this->assertTrue(JobChainingTestFirstJob::$ran);
+        $this->assertTrue(JobChainingTestSecondJob::$ran);
+    }
+}
+
+
+class JobChainingTestFirstJob implements ShouldQueue
+{
+    use Dispatchable, Queueable;
+
+    public static $ran = false;
+
+    public function handle()
+    {
+        static::$ran = true;
+    }
+}
+
+
+class JobChainingTestSecondJob implements ShouldQueue
+{
+    use Dispatchable, Queueable;
+
+    public static $ran = false;
+
+    public function handle()
+    {
+        static::$ran = true;
+    }
+}