Add some tests

Also, retrieve tag from the request instead of the query (which will be the same but it's more easy to test).

Moved down `deleteTagAction` because it conflicted with the new action:

  api_delete_tag => /api/tags/{tag}.{_format}
  api_delete_tags_label => /api/tags/label.{_format}

And finally, throw exception when a tag is not found before removing it.

tests/Wallabag/ApiBundle/Controller/WallabagRestControllerTest.php

@@ -3,6 +3,7 @@
 namespace Tests\Wallabag\ApiBundle\Controller;
 
 use Tests\Wallabag\ApiBundle\WallabagApiTestCase;
+use Wallabag\CoreBundle\Entity\Tag;
 
 class WallabagRestControllerTest extends WallabagApiTestCase
 {
@@ -359,7 +360,7 @@ class WallabagRestControllerTest extends WallabagApiTestCase
         $entry = $this->client->getContainer()
             ->get('doctrine.orm.entity_manager')
             ->getRepository('WallabagCoreBundle:Entry')
-            ->findOneWithTags(1);
+            ->findOneWithTags($this->user->getId());
 
         $entry = $entry[0];
 
@@ -421,7 +422,7 @@ class WallabagRestControllerTest extends WallabagApiTestCase
         $entry = $this->client->getContainer()
             ->get('doctrine.orm.entity_manager')
             ->getRepository('WallabagCoreBundle:Entry')
-            ->findOneWithTags(1);
+            ->findOneWithTags($this->user->getId());
         $entry = $entry[0];
 
         if (!$entry) {
@@ -472,7 +473,7 @@ class WallabagRestControllerTest extends WallabagApiTestCase
         $this->assertEquals($tag['label'], $content['label']);
         $this->assertEquals($tag['slug'], $content['slug']);
 
-        $entries = $entry = $this->client->getContainer()
+        $entries = $this->client->getContainer()
             ->get('doctrine.orm.entity_manager')
             ->getRepository('WallabagCoreBundle:Entry')
             ->findAllByTagId($this->user->getId(), $tag['id']);
@@ -480,6 +481,112 @@ class WallabagRestControllerTest extends WallabagApiTestCase
         $this->assertCount(0, $entries);
     }
 
+    public function testDeleteTagByLabel()
+    {
+        $em = $this->client->getContainer()->get('doctrine.orm.entity_manager');
+        $entry = $this->client->getContainer()
+            ->get('doctrine.orm.entity_manager')
+            ->getRepository('WallabagCoreBundle:Entry')
+            ->findOneWithTags($this->user->getId());
+
+        $entry = $entry[0];
+
+        $tag = new Tag();
+        $tag->setLabel('Awesome tag for test');
+        $em->persist($tag);
+
+        $entry->addTag($tag);
+
+        $em->persist($entry);
+        $em->flush();
+
+        $this->client->request('DELETE', '/api/tag/label.json', ['tag' => $tag->getLabel()]);
+
+        $this->assertEquals(200, $this->client->getResponse()->getStatusCode());
+
+        $content = json_decode($this->client->getResponse()->getContent(), true);
+
+        $this->assertArrayHasKey('label', $content);
+        $this->assertEquals($tag->getLabel(), $content['label']);
+        $this->assertEquals($tag->getSlug(), $content['slug']);
+
+        $entries = $this->client->getContainer()
+            ->get('doctrine.orm.entity_manager')
+            ->getRepository('WallabagCoreBundle:Entry')
+            ->findAllByTagId($this->user->getId(), $tag->getId());
+
+        $this->assertCount(0, $entries);
+    }
+
+    public function testDeleteTagByLabelNotFound()
+    {
+        $this->client->request('DELETE', '/api/tag/label.json', ['tag' => 'does not exist']);
+
+        $this->assertEquals(404, $this->client->getResponse()->getStatusCode());
+    }
+
+    public function testDeleteTagsByLabel()
+    {
+        $em = $this->client->getContainer()->get('doctrine.orm.entity_manager');
+        $entry = $this->client->getContainer()
+            ->get('doctrine.orm.entity_manager')
+            ->getRepository('WallabagCoreBundle:Entry')
+            ->findOneWithTags($this->user->getId());
+
+        $entry = $entry[0];
+
+        $tag = new Tag();
+        $tag->setLabel('Awesome tag for tagsLabel');
+        $em->persist($tag);
+
+        $tag2 = new Tag();
+        $tag2->setLabel('Awesome tag for tagsLabel 2');
+        $em->persist($tag2);
+
+        $entry->addTag($tag);
+        $entry->addTag($tag2);
+
+        $em->persist($entry);
+        $em->flush();
+
+        $this->client->request('DELETE', '/api/tags/label.json', ['tags' => $tag->getLabel().','.$tag2->getLabel()]);
+
+        $this->assertEquals(200, $this->client->getResponse()->getStatusCode());
+
+        $content = json_decode($this->client->getResponse()->getContent(), true);
+
+        $this->assertCount(2, $content);
+
+        $this->assertArrayHasKey('label', $content[0]);
+        $this->assertEquals($tag->getLabel(), $content[0]['label']);
+        $this->assertEquals($tag->getSlug(), $content[0]['slug']);
+
+        $this->assertArrayHasKey('label', $content[1]);
+        $this->assertEquals($tag2->getLabel(), $content[1]['label']);
+        $this->assertEquals($tag2->getSlug(), $content[1]['slug']);
+
+        $entries = $this->client->getContainer()
+            ->get('doctrine.orm.entity_manager')
+            ->getRepository('WallabagCoreBundle:Entry')
+            ->findAllByTagId($this->user->getId(), $tag->getId());
+
+        $this->assertCount(0, $entries);
+
+        $entries = $this->client->getContainer()
+            ->get('doctrine.orm.entity_manager')
+            ->getRepository('WallabagCoreBundle:Entry')
+            ->findAllByTagId($this->user->getId(), $tag2->getId());
+
+        $this->assertCount(0, $entries);
+    }
+
+    public function testDeleteTagsByLabelNotFound()
+    {
+        $this->client->request('DELETE', '/api/tags/label.json', ['tags' => 'does not exist']);
+
+        $this->assertEquals(404, $this->client->getResponse()->getStatusCode());
+    }
+
     public function testGetVersion()
     {
         $this->client->request('GET', '/api/version');