Added test to verify tags when used with deferred. (#65)

* Added test to verify tags when used with deferred.

* allow skip

* Require tag-interop

composer.json

@@ -23,7 +23,8 @@
     ],
     "require":     {
         "php":       "^5.4|^7",
-        "psr/cache": "~1.0"
+        "psr/cache": "~1.0",
+        "cache/tag-interop": "^1.0"
     },
     "require-dev": {
         "phpunit/phpunit": "^4.0|^5.0",

src/TaggableCachePoolTest.php

@@ -11,7 +11,7 @@
 
 namespace Cache\IntegrationTests;
 
-use Cache\Adapter\Common\TaggableCacheItemPoolInterface;
+use Cache\TagInterop\TaggableCacheItemPoolInterface;
 
 /**
  * @author Tobias Nyholm <[email protected]>
@@ -99,6 +99,25 @@ public function testPreviousTag()
         $this->assertCount(1, $item->getPreviousTags());
     }
 
+    public function testPreviousTagDeferred()
+    {
+        if (isset($this->skippedTests[__FUNCTION__])) {
+            $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
+
+            return;
+        }
+
+        $item = $this->cache->getItem('key')->set('value');
+        $item->setTags(['tag0']);
+        $this->assertCount(0, $item->getPreviousTags());
+
+        $this->cache->saveDeferred($item);
+        $this->assertCount(0, $item->getPreviousTags());
+
+        $item = $this->cache->getItem('key');
+        $this->assertCount(1, $item->getPreviousTags());
+    }
+
     /**
      * @expectedException \Psr\Cache\InvalidArgumentException
      */
@@ -260,6 +279,12 @@ public function testInvalidateTags()
      */
     public function testTagsAreCleanedOnSave()
     {
+        if (isset($this->skippedTests[__FUNCTION__])) {
+            $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
+
+            return;
+        }
+
         $pool = $this->cache;
         $i    = $pool->getItem('key')->set('value');
         $pool->save($i->setTags(['foo']));