Add method to attach result at specific index

src/Result.php

@@ -277,9 +277,32 @@ public function addRows(array $rows)
         return $this;
     }
 
+    /**
+     * Append this result to the list of results.
+     *
+     * @return self
+     */
     public function attach()
     {
         $this->wye()->addResult($this);
         return $this;
     }
+
+    /**
+     * Attach this result at the specified index. Without an index the result
+     * will be appended to the list of results.
+     *
+     * @param  integer|null $index
+     * @return self
+     */
+    public function attachAtIndex($index = null)
+    {
+        if (is_null($index)) {
+            return $this->attach();
+        }
+
+        $this->getWye()->addResultAtIndex($this, $index);
+
+        return $this;
+    }
 }

tests/Unit/Result/AttachAtIndexTest.php

@@ -0,0 +1,32 @@
+<?php
+
+namespace Tests\Unit\Result;
+
+use Stratedge\Wye\Wye;
+
+class AttachAtIndexTest extends \Tests\TestCase
+{
+    public function testAppendsWithoutIndex()
+    {
+        $result = Wye::makeResult()->attach();
+        $new_result = Wye::makeResult()->attachAtIndex();
+
+        $this->assertSame([$result, $new_result], Wye::getResults());
+    }
+
+    public function testAddsResultAtIndex()
+    {
+        $result = Wye::makeResult()->attach();
+        $new_result = Wye::makeResult()->attachAtIndex(3);
+
+        $this->assertSame([0 => $result, 3 => $new_result], Wye::getResults());
+    }
+
+    public function testOverwritesResultAtIndex()
+    {
+        $result = Wye::makeResult()->attach();
+        $new_result = Wye::makeResult()->attachAtIndex(0);
+
+        $this->assertSame([$new_result], Wye::getResults());
+    }
+}

tests/Unit/Result/AttachTest.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace Tests\Unit\Result;
+
+use Stratedge\Wye\Wye;
+
+class AttachTest extends \Tests\TestCase
+{
+    public function testAppendsResult()
+    {
+        $result = Wye::makeResult()->attach();
+        $new_result = Wye::makeResult()->attach();
+
+        $this->assertSame([$result, $new_result], Wye::getResults());
+    }
+}