Throw different exception for failed test op

Having this additional exception type allows users to distinguish
between apply() errors due to the patch not being applicable and failed
test operations.

Author: jakobw

src/JsonPatch.php

@@ -170,7 +170,7 @@ public function apply(&$original, $stopOnError = true)
                         $diff = new JsonDiff($operation->value, $value,
                             JsonDiff::STOP_ON_DIFF);
                         if ($diff->getDiffCnt() !== 0) {
-                            throw new Exception('Test operation ' . json_encode($operation, JSON_UNESCAPED_SLASHES)
+                            throw new PatchTestOperationFailedException('Test operation ' . json_encode($operation, JSON_UNESCAPED_SLASHES)
                                 . ' failed: ' . json_encode($value));
                         }
                         break;

src/PatchTestConditionFailedException.php

@@ -0,0 +1,8 @@
+<?php
+
+namespace Swaggest\JsonDiff;
+
+
+class PatchTestOperationFailedException extends Exception
+{
+}

tests/src/JsonPatchTest.php

@@ -5,6 +5,7 @@
 use Swaggest\JsonDiff\Exception;
 use Swaggest\JsonDiff\JsonDiff;
 use Swaggest\JsonDiff\JsonPatch;
+use Swaggest\JsonDiff\PatchTestOperationFailedException;
 
 class JsonPatchTest extends \PHPUnit_Framework_TestCase
 {
@@ -142,4 +143,13 @@ public function testApplyNonExistentLevelOne()
         $this->assertEquals((object)array('some' => 22), $data);
     }
 
+    public function testTestOperationFailed()
+    {
+        $data = array('abc' => 'xyz');
+        $p = new JsonPatch();
+        $p->op(new JsonPatch\Test('/abc', 'def'));
+        $errors = $p->apply($data, false);
+        $this->assertInstanceOf(PatchTestOperationFailedException::class, $errors[0]);
+    }
+
 }