diff --git a/analysis_options.yaml b/analysis_options.yaml
index 2c9d809..d74c8fe 100644
--- a/analysis_options.yaml
+++ b/analysis_options.yaml
@@ -33,3 +33,4 @@ linter:
      - slash_for_doc_comments
      - type_init_formals
      - unnecessary_new
+     - prefer_single_quotes
diff --git a/example/main.dart b/example/main.dart
index a722833..7a4500c 100644
--- a/example/main.dart
+++ b/example/main.dart
@@ -6,12 +6,12 @@ void main() async {
 
   // RSS feed
   var response = await client
-      .get("https://developer.apple.com/news/releases/rss/releases.rss");
+      .get('https://developer.apple.com/news/releases/rss/releases.rss');
   var channel = RssFeed.parse(response.body);
   print(channel);
 
   // Atom feed
-  response = await client.get("https://www.theverge.com/rss/index.xml");
+  response = await client.get('https://www.theverge.com/rss/index.xml');
   var feed = AtomFeed.parse(response.body);
   print(feed);
 
diff --git a/lib/domain/atom_category.dart b/lib/domain/atom_category.dart
index 22c6a97..acd5b58 100644
--- a/lib/domain/atom_category.dart
+++ b/lib/domain/atom_category.dart
@@ -8,9 +8,9 @@ class AtomCategory {
   AtomCategory(this.term, this.scheme, this.label);
 
   factory AtomCategory.parse(XmlElement element) {
-    var term = element.getAttribute("term");
-    var scheme = element.getAttribute("scheme");
-    var label = element.getAttribute("label");
+    var term = element.getAttribute('term');
+    var scheme = element.getAttribute('scheme');
+    var label = element.getAttribute('label');
     return AtomCategory(term, scheme, label);
   }
 }
diff --git a/lib/domain/atom_feed.dart b/lib/domain/atom_feed.dart
index 06d1b2c..8a4f75e 100644
--- a/lib/domain/atom_feed.dart
+++ b/lib/domain/atom_feed.dart
@@ -43,36 +43,36 @@ class AtomFeed {
     var document = XmlDocument.parse(xmlString);
     XmlElement feedElement;
     try {
-      feedElement = document.findElements("feed").first;
+      feedElement = document.findElements('feed').first;
     } on StateError {
-      throw ArgumentError("feed not found");
+      throw ArgumentError('feed not found');
     }
 
     return AtomFeed(
-      id: findElementOrNull(feedElement, "id")?.text,
-      title: findElementOrNull(feedElement, "title")?.text,
-      updated: parseDateTime(findElementOrNull(feedElement, "updated")?.text),
-      items: feedElement.findElements("entry").map((element) {
+      id: findElementOrNull(feedElement, 'id')?.text,
+      title: findElementOrNull(feedElement, 'title')?.text,
+      updated: parseDateTime(findElementOrNull(feedElement, 'updated')?.text),
+      items: feedElement.findElements('entry').map((element) {
         return AtomItem.parse(element);
       }).toList(),
-      links: feedElement.findElements("link").map((element) {
+      links: feedElement.findElements('link').map((element) {
         return AtomLink.parse(element);
       }).toList(),
-      authors: feedElement.findElements("author").map((element) {
+      authors: feedElement.findElements('author').map((element) {
         return AtomPerson.parse(element);
       }).toList(),
-      contributors: feedElement.findElements("contributor").map((element) {
+      contributors: feedElement.findElements('contributor').map((element) {
         return AtomPerson.parse(element);
       }).toList(),
-      categories: feedElement.findElements("category").map((element) {
+      categories: feedElement.findElements('category').map((element) {
         return AtomCategory.parse(element);
       }).toList(),
       generator:
-          AtomGenerator.parse(findElementOrNull(feedElement, "generator")),
-      icon: findElementOrNull(feedElement, "icon")?.text,
-      logo: findElementOrNull(feedElement, "logo")?.text,
-      rights: findElementOrNull(feedElement, "rights")?.text,
-      subtitle: findElementOrNull(feedElement, "subtitle")?.text,
+          AtomGenerator.parse(findElementOrNull(feedElement, 'generator')),
+      icon: findElementOrNull(feedElement, 'icon')?.text,
+      logo: findElementOrNull(feedElement, 'logo')?.text,
+      rights: findElementOrNull(feedElement, 'rights')?.text,
+      subtitle: findElementOrNull(feedElement, 'subtitle')?.text,
     );
   }
 }
diff --git a/lib/domain/atom_generator.dart b/lib/domain/atom_generator.dart
index 14eb70d..b3a0b5f 100644
--- a/lib/domain/atom_generator.dart
+++ b/lib/domain/atom_generator.dart
@@ -11,8 +11,8 @@ class AtomGenerator {
     if (element == null) {
       return null;
     }
-    var uri = element.getAttribute("uri");
-    var version = element.getAttribute("version");
+    var uri = element.getAttribute('uri');
+    var version = element.getAttribute('version');
     var value = element.text;
     return AtomGenerator(uri, version, value);
   }
diff --git a/lib/domain/atom_item.dart b/lib/domain/atom_item.dart
index f04181f..2b93ccc 100644
--- a/lib/domain/atom_item.dart
+++ b/lib/domain/atom_item.dart
@@ -41,26 +41,26 @@ class AtomItem {
 
   factory AtomItem.parse(XmlElement element) {
     return AtomItem(
-      id: findElementOrNull(element, "id")?.text,
-      title: findElementOrNull(element, "title")?.text,
-      updated: parseDateTime(findElementOrNull(element, "updated")?.text),
-      authors: element.findElements("author").map((element) {
+      id: findElementOrNull(element, 'id')?.text,
+      title: findElementOrNull(element, 'title')?.text,
+      updated: parseDateTime(findElementOrNull(element, 'updated')?.text),
+      authors: element.findElements('author').map((element) {
         return AtomPerson.parse(element);
       }).toList(),
-      links: element.findElements("link").map((element) {
+      links: element.findElements('link').map((element) {
         return AtomLink.parse(element);
       }).toList(),
-      categories: element.findElements("category").map((element) {
+      categories: element.findElements('category').map((element) {
         return AtomCategory.parse(element);
       }).toList(),
-      contributors: element.findElements("contributor").map((element) {
+      contributors: element.findElements('contributor').map((element) {
         return AtomPerson.parse(element);
       }).toList(),
-      source: AtomSource.parse(findElementOrNull(element, "source")),
-      published: findElementOrNull(element, "published")?.text,
-      content: findElementOrNull(element, "content")?.text,
-      summary: findElementOrNull(element, "summary")?.text,
-      rights: findElementOrNull(element, "rights")?.text,
+      source: AtomSource.parse(findElementOrNull(element, 'source')),
+      published: findElementOrNull(element, 'published')?.text,
+      content: findElementOrNull(element, 'content')?.text,
+      summary: findElementOrNull(element, 'summary')?.text,
+      rights: findElementOrNull(element, 'rights')?.text,
       media: Media.parse(element),
     );
   }
diff --git a/lib/domain/atom_link.dart b/lib/domain/atom_link.dart
index 3b570f2..9b68ac2 100644
--- a/lib/domain/atom_link.dart
+++ b/lib/domain/atom_link.dart
@@ -18,14 +18,14 @@ class AtomLink {
   );
 
   factory AtomLink.parse(XmlElement element) {
-    var href = element.getAttribute("href");
-    var rel = element.getAttribute("rel");
-    var type = element.getAttribute("type");
-    var title = element.getAttribute("title");
-    var hreflang = element.getAttribute("hreflang");
+    var href = element.getAttribute('href');
+    var rel = element.getAttribute('rel');
+    var type = element.getAttribute('type');
+    var title = element.getAttribute('title');
+    var hreflang = element.getAttribute('hreflang');
     var length = 0;
-    if (element.getAttribute("length") != null) {
-      length = int.parse(element.getAttribute("length"));
+    if (element.getAttribute('length') != null) {
+      length = int.parse(element.getAttribute('length'));
     }
     return AtomLink(href, rel, type, hreflang, title, length);
   }
diff --git a/lib/domain/atom_person.dart b/lib/domain/atom_person.dart
index c68fe45..1d84e6c 100644
--- a/lib/domain/atom_person.dart
+++ b/lib/domain/atom_person.dart
@@ -9,9 +9,9 @@ class AtomPerson {
   AtomPerson(this.name, this.uri, this.email);
 
   factory AtomPerson.parse(XmlElement element) {
-    var name = findElementOrNull(element, "name")?.text;
-    var uri = findElementOrNull(element, "uri")?.text;
-    var email = findElementOrNull(element, "email")?.text;
+    var name = findElementOrNull(element, 'name')?.text;
+    var uri = findElementOrNull(element, 'uri')?.text;
+    var email = findElementOrNull(element, 'email')?.text;
     return AtomPerson(name, uri, email);
   }
 }
diff --git a/lib/domain/atom_source.dart b/lib/domain/atom_source.dart
index d632d5a..9f1b34b 100644
--- a/lib/domain/atom_source.dart
+++ b/lib/domain/atom_source.dart
@@ -12,9 +12,9 @@ class AtomSource {
     if (element == null) {
       return null;
     }
-    var id = findElementOrNull(element, "id")?.text;
-    var title = findElementOrNull(element, "title")?.text;
-    var updated = findElementOrNull(element, "updated")?.text;
+    var id = findElementOrNull(element, 'id')?.text;
+    var title = findElementOrNull(element, 'title')?.text;
+    var updated = findElementOrNull(element, 'updated')?.text;
 
     return AtomSource(id, title, updated);
   }
diff --git a/lib/domain/dublin_core/dublin_core.dart b/lib/domain/dublin_core/dublin_core.dart
index 53a496c..b36c004 100644
--- a/lib/domain/dublin_core/dublin_core.dart
+++ b/lib/domain/dublin_core/dublin_core.dart
@@ -46,23 +46,23 @@ class DublinCore {
       return null;
     }
     return DublinCore(
-      title: findElementOrNull(element, "dc:title")?.text,
-      description: findElementOrNull(element, "dc:description")?.text,
-      creator: findElementOrNull(element, "dc:creator")?.text,
-      subject: findElementOrNull(element, "dc:subject")?.text,
-      publisher: findElementOrNull(element, "dc:publisher")?.text,
-      contributor: findElementOrNull(element, "dc:contributor")?.text,
-      date: parseDateTime(findElementOrNull(element, "dc:date")?.text),
-      created: parseDateTime(findElementOrNull(element, "dc:created")?.text),
-      modified: parseDateTime(findElementOrNull(element, "dc:modified")?.text),
-      type: findElementOrNull(element, "dc:type")?.text,
-      format: findElementOrNull(element, "dc:format")?.text,
-      identifier: findElementOrNull(element, "dc:identifier")?.text,
-      source: findElementOrNull(element, "dc:source")?.text,
-      language: findElementOrNull(element, "dc:language")?.text,
-      relation: findElementOrNull(element, "dc:relation")?.text,
-      coverage: findElementOrNull(element, "dc:coverage")?.text,
-      rights: findElementOrNull(element, "dc:rights")?.text,
+      title: findElementOrNull(element, 'dc:title')?.text,
+      description: findElementOrNull(element, 'dc:description')?.text,
+      creator: findElementOrNull(element, 'dc:creator')?.text,
+      subject: findElementOrNull(element, 'dc:subject')?.text,
+      publisher: findElementOrNull(element, 'dc:publisher')?.text,
+      contributor: findElementOrNull(element, 'dc:contributor')?.text,
+      date: parseDateTime(findElementOrNull(element, 'dc:date')?.text),
+      created: parseDateTime(findElementOrNull(element, 'dc:created')?.text),
+      modified: parseDateTime(findElementOrNull(element, 'dc:modified')?.text),
+      type: findElementOrNull(element, 'dc:type')?.text,
+      format: findElementOrNull(element, 'dc:format')?.text,
+      identifier: findElementOrNull(element, 'dc:identifier')?.text,
+      source: findElementOrNull(element, 'dc:source')?.text,
+      language: findElementOrNull(element, 'dc:language')?.text,
+      relation: findElementOrNull(element, 'dc:relation')?.text,
+      coverage: findElementOrNull(element, 'dc:coverage')?.text,
+      rights: findElementOrNull(element, 'dc:rights')?.text,
     );
   }
 }
diff --git a/lib/domain/media/category.dart b/lib/domain/media/category.dart
index 9029738..967e0a2 100644
--- a/lib/domain/media/category.dart
+++ b/lib/domain/media/category.dart
@@ -16,8 +16,8 @@ class Category {
       return null;
     }
     return Category(
-      scheme: element.getAttribute("scheme"),
-      label: element.getAttribute("label"),
+      scheme: element.getAttribute('scheme'),
+      label: element.getAttribute('label'),
       value: element.text,
     );
   }
diff --git a/lib/domain/media/community.dart b/lib/domain/media/community.dart
index 6f1c685..fcbbf8a 100644
--- a/lib/domain/media/community.dart
+++ b/lib/domain/media/community.dart
@@ -21,13 +21,13 @@ class Community {
     }
     return Community(
       starRating: StarRating.parse(
-        findElementOrNull(element, "media:starRating"),
+        findElementOrNull(element, 'media:starRating'),
       ),
       statistics: Statistics.parse(
-        findElementOrNull(element, "media:statistics"),
+        findElementOrNull(element, 'media:statistics'),
       ),
       tags: Tags.parse(
-        findElementOrNull(element, "media:tags"),
+        findElementOrNull(element, 'media:tags'),
       ),
     );
   }
diff --git a/lib/domain/media/content.dart b/lib/domain/media/content.dart
index e580e5f..061119c 100644
--- a/lib/domain/media/content.dart
+++ b/lib/domain/media/content.dart
@@ -35,22 +35,22 @@ class Content {
 
   factory Content.parse(XmlElement element) {
     return Content(
-      url: element.getAttribute("url"),
-      type: element.getAttribute("type"),
-      fileSize: int.tryParse(element.getAttribute("fileSize") ?? "0"),
-      medium: element.getAttribute("medium"),
-      isDefault: element.getAttribute("isDefault") == "true",
-      expression: element.getAttribute("expression"),
-      bitrate: int.tryParse(element.getAttribute("bitrate") ?? "0"),
-      framerate: double.tryParse(element.getAttribute("framerate") ?? "0"),
+      url: element.getAttribute('url'),
+      type: element.getAttribute('type'),
+      fileSize: int.tryParse(element.getAttribute('fileSize') ?? '0'),
+      medium: element.getAttribute('medium'),
+      isDefault: element.getAttribute('isDefault') == 'true',
+      expression: element.getAttribute('expression'),
+      bitrate: int.tryParse(element.getAttribute('bitrate') ?? '0'),
+      framerate: double.tryParse(element.getAttribute('framerate') ?? '0'),
       samplingrate: double.tryParse(
-        element.getAttribute("samplingrate") ?? "0",
+        element.getAttribute('samplingrate') ?? '0',
       ),
-      channels: int.tryParse(element.getAttribute("channels") ?? "0"),
-      duration: int.tryParse(element.getAttribute("duration") ?? "0"),
-      height: int.tryParse(element.getAttribute("height") ?? "0"),
-      width: int.tryParse(element.getAttribute("width") ?? "0"),
-      lang: element.getAttribute("lang"),
+      channels: int.tryParse(element.getAttribute('channels') ?? '0'),
+      duration: int.tryParse(element.getAttribute('duration') ?? '0'),
+      height: int.tryParse(element.getAttribute('height') ?? '0'),
+      width: int.tryParse(element.getAttribute('width') ?? '0'),
+      lang: element.getAttribute('lang'),
     );
   }
 }
diff --git a/lib/domain/media/copyright.dart b/lib/domain/media/copyright.dart
index f4b5b8b..e40c4c7 100644
--- a/lib/domain/media/copyright.dart
+++ b/lib/domain/media/copyright.dart
@@ -14,7 +14,7 @@ class Copyright {
       return null;
     }
     return Copyright(
-      url: element.getAttribute("url"),
+      url: element.getAttribute('url'),
       value: element.text,
     );
   }
diff --git a/lib/domain/media/credit.dart b/lib/domain/media/credit.dart
index 212dac1..3f0838b 100644
--- a/lib/domain/media/credit.dart
+++ b/lib/domain/media/credit.dart
@@ -13,8 +13,8 @@ class Credit {
 
   factory Credit.parse(XmlElement element) {
     return Credit(
-      role: element.getAttribute("role"),
-      scheme: element.getAttribute("scheme"),
+      role: element.getAttribute('role'),
+      scheme: element.getAttribute('scheme'),
       value: element.text,
     );
   }
diff --git a/lib/domain/media/description.dart b/lib/domain/media/description.dart
index 17bb1cb..29866d0 100644
--- a/lib/domain/media/description.dart
+++ b/lib/domain/media/description.dart
@@ -14,7 +14,7 @@ class Description {
       return null;
     }
     return Description(
-      type: element.getAttribute("type"),
+      type: element.getAttribute('type'),
       value: element.text,
     );
   }
diff --git a/lib/domain/media/embed.dart b/lib/domain/media/embed.dart
index 6fc84ea..81555be 100644
--- a/lib/domain/media/embed.dart
+++ b/lib/domain/media/embed.dart
@@ -19,10 +19,10 @@ class Embed {
       return null;
     }
     return Embed(
-      url: element.getAttribute("url"),
-      width: int.tryParse(element.getAttribute("width") ?? "0"),
-      height: int.tryParse(element.getAttribute("height") ?? "0"),
-      params: element.findElements("media:param").map((e) {
+      url: element.getAttribute('url'),
+      width: int.tryParse(element.getAttribute('width') ?? '0'),
+      height: int.tryParse(element.getAttribute('height') ?? '0'),
+      params: element.findElements('media:param').map((e) {
         return Param.parse(e);
       }).toList(),
     );
diff --git a/lib/domain/media/group.dart b/lib/domain/media/group.dart
index 2be5efd..7f656a9 100644
--- a/lib/domain/media/group.dart
+++ b/lib/domain/media/group.dart
@@ -23,17 +23,17 @@ class Group {
       return null;
     }
     return Group(
-      contents: element.findElements("media:content").map((e) {
+      contents: element.findElements('media:content').map((e) {
         return Content.parse(e);
       }).toList(),
-      credits: element.findElements("media:credit").map((e) {
+      credits: element.findElements('media:credit').map((e) {
         return Credit.parse(e);
       }).toList(),
       category: Category.parse(
-        findElementOrNull(element, "media:category"),
+        findElementOrNull(element, 'media:category'),
       ),
       rating: Rating.parse(
-        findElementOrNull(element, "media:rating"),
+        findElementOrNull(element, 'media:rating'),
       ),
     );
   }
diff --git a/lib/domain/media/hash.dart b/lib/domain/media/hash.dart
index 01ad1c3..bfcbd72 100644
--- a/lib/domain/media/hash.dart
+++ b/lib/domain/media/hash.dart
@@ -14,7 +14,7 @@ class Hash {
       return null;
     }
     return Hash(
-      algo: element.getAttribute("algo"),
+      algo: element.getAttribute('algo'),
       value: element.text,
     );
   }
diff --git a/lib/domain/media/license.dart b/lib/domain/media/license.dart
index 75db98e..e3990db 100644
--- a/lib/domain/media/license.dart
+++ b/lib/domain/media/license.dart
@@ -16,8 +16,8 @@ class License {
       return null;
     }
     return License(
-      type: element.getAttribute("type"),
-      href: element.getAttribute("href"),
+      type: element.getAttribute('type'),
+      href: element.getAttribute('href'),
       value: element.text,
     );
   }
diff --git a/lib/domain/media/media.dart b/lib/domain/media/media.dart
index fc37773..c5655a2 100644
--- a/lib/domain/media/media.dart
+++ b/lib/domain/media/media.dart
@@ -80,86 +80,86 @@ class Media {
   factory Media.parse(XmlElement element) {
     return Media(
       group: Group.parse(
-        findElementOrNull(element, "media:group"),
+        findElementOrNull(element, 'media:group'),
       ),
-      contents: element.findElements("media:content").map((e) {
+      contents: element.findElements('media:content').map((e) {
         return Content.parse(e);
       }).toList(),
-      credits: element.findElements("media:credit").map((e) {
+      credits: element.findElements('media:credit').map((e) {
         return Credit.parse(e);
       }).toList(),
       category: Category.parse(
-        findElementOrNull(element, "media:category"),
+        findElementOrNull(element, 'media:category'),
       ),
       rating: Rating.parse(
-        findElementOrNull(element, "media:rating"),
+        findElementOrNull(element, 'media:rating'),
       ),
       title: Title.parse(
-        findElementOrNull(element, "media:title"),
+        findElementOrNull(element, 'media:title'),
       ),
       description: Description.parse(
-        findElementOrNull(element, "media:description"),
+        findElementOrNull(element, 'media:description'),
       ),
-      keywords: findElementOrNull(element, "media:keywords")?.text,
-      thumbnails: element.findElements("media:thumbnail").map((e) {
+      keywords: findElementOrNull(element, 'media:keywords')?.text,
+      thumbnails: element.findElements('media:thumbnail').map((e) {
         return Thumbnail.parse(e);
       }).toList(),
       hash: Hash.parse(
-        findElementOrNull(element, "media:hash"),
+        findElementOrNull(element, 'media:hash'),
       ),
       player: Player.parse(
-        findElementOrNull(element, "media:player"),
+        findElementOrNull(element, 'media:player'),
       ),
       copyright: Copyright.parse(
-        findElementOrNull(element, "media:copyright"),
+        findElementOrNull(element, 'media:copyright'),
       ),
       text: Text.parse(
-        findElementOrNull(element, "media:text"),
+        findElementOrNull(element, 'media:text'),
       ),
       restriction: Restriction.parse(
-        findElementOrNull(element, "media:restriction"),
+        findElementOrNull(element, 'media:restriction'),
       ),
       community: Community.parse(
-        findElementOrNull(element, "media:community"),
+        findElementOrNull(element, 'media:community'),
       ),
-      comments: findElementOrNull(element, "media:comments")
-              ?.findElements("media:comment")
+      comments: findElementOrNull(element, 'media:comments')
+              ?.findElements('media:comment')
               ?.map((e) {
             return e.text;
           })?.toList() ??
           [],
       embed: Embed.parse(
-        findElementOrNull(element, "media:embed"),
+        findElementOrNull(element, 'media:embed'),
       ),
-      responses: findElementOrNull(element, "media:responses")
-              ?.findElements("media:response")
+      responses: findElementOrNull(element, 'media:responses')
+              ?.findElements('media:response')
               ?.map((e) {
             return e.text;
           })?.toList() ??
           [],
-      backLinks: findElementOrNull(element, "media:backLinks")
-              ?.findElements("media:backLink")
+      backLinks: findElementOrNull(element, 'media:backLinks')
+              ?.findElements('media:backLink')
               ?.map((e) {
             return e.text;
           })?.toList() ??
           [],
       status: Status.parse(
-        findElementOrNull(element, "media:status"),
+        findElementOrNull(element, 'media:status'),
       ),
-      prices: element.findElements("media:price").map((e) {
+      prices: element.findElements('media:price').map((e) {
         return Price.parse(e);
       }).toList(),
       license: License.parse(
-        findElementOrNull(element, "media:license"),
+        findElementOrNull(element, 'media:license'),
       ),
       peerLink: PeerLink.parse(
-        findElementOrNull(element, "media:peerLink"),
+        findElementOrNull(element, 'media:peerLink'),
       ),
       rights: Rights.parse(
-        findElementOrNull(element, "media:rights"),
+        findElementOrNull(element, 'media:rights'),
       ),
-      scenes: findElementOrNull(element, "media:scenes")
-              ?.findElements("media:scene")
+      scenes: findElementOrNull(element, 'media:scenes')
+              ?.findElements('media:scene')
               ?.map((e) {
             return Scene.parse(e);
           })?.toList() ??
diff --git a/lib/domain/media/param.dart b/lib/domain/media/param.dart
index f6299c8..ac42675 100644
--- a/lib/domain/media/param.dart
+++ b/lib/domain/media/param.dart
@@ -14,7 +14,7 @@ class Param {
       return null;
     }
     return Param(
-      name: element.getAttribute("name"),
+      name: element.getAttribute('name'),
       value: element.text,
     );
   }
diff --git a/lib/domain/media/peer_link.dart b/lib/domain/media/peer_link.dart
index dd06d90..08a5524 100644
--- a/lib/domain/media/peer_link.dart
+++ b/lib/domain/media/peer_link.dart
@@ -16,8 +16,8 @@ class PeerLink {
       return null;
     }
     return PeerLink(
-      type: element.getAttribute("type"),
-      href: element.getAttribute("href"),
+      type: element.getAttribute('type'),
+      href: element.getAttribute('href'),
       value: element.text,
     );
   }
diff --git a/lib/domain/media/player.dart b/lib/domain/media/player.dart
index 14b2a54..2036445 100644
--- a/lib/domain/media/player.dart
+++ b/lib/domain/media/player.dart
@@ -18,9 +18,9 @@ class Player {
       return null;
     }
     return Player(
-      url: element.getAttribute("url"),
-      width: int.tryParse(element.getAttribute("width") ?? "0"),
-      height: int.tryParse(element.getAttribute("height") ?? "0"),
+      url: element.getAttribute('url'),
+      width: int.tryParse(element.getAttribute('width') ?? '0'),
+      height: int.tryParse(element.getAttribute('height') ?? '0'),
       value: element.text,
     );
   }
diff --git a/lib/domain/media/price.dart b/lib/domain/media/price.dart
index 6b930ce..4ac9059 100644
--- a/lib/domain/media/price.dart
+++ b/lib/domain/media/price.dart
@@ -15,10 +15,10 @@ class Price {
 
   factory Price.parse(XmlElement element) {
     return Price(
-      price: double.tryParse(element.getAttribute("price") ?? "0"),
-      type: element.getAttribute("type"),
-      info: element.getAttribute("info"),
-      currency: element.getAttribute("currency"),
+      price: double.tryParse(element.getAttribute('price') ?? '0'),
+      type: element.getAttribute('type'),
+      info: element.getAttribute('info'),
+      currency: element.getAttribute('currency'),
     );
   }
 }
diff --git a/lib/domain/media/rating.dart b/lib/domain/media/rating.dart
index 5a53f88..7924cdd 100644
--- a/lib/domain/media/rating.dart
+++ b/lib/domain/media/rating.dart
@@ -14,7 +14,7 @@ class Rating {
       return null;
     }
     return Rating(
-      scheme: element.getAttribute("scheme"),
+      scheme: element.getAttribute('scheme'),
       value: element.text,
     );
   }
diff --git a/lib/domain/media/restriction.dart b/lib/domain/media/restriction.dart
index 59a5339..cc896e9 100644
--- a/lib/domain/media/restriction.dart
+++ b/lib/domain/media/restriction.dart
@@ -16,8 +16,8 @@ class Restriction {
       return null;
     }
     return Restriction(
-      relationship: element.getAttribute("relationship"),
-      type: element.getAttribute("type"),
+      relationship: element.getAttribute('relationship'),
+      type: element.getAttribute('type'),
       value: element.text,
     );
   }
diff --git a/lib/domain/media/rights.dart b/lib/domain/media/rights.dart
index 38feed3..2dfd20b 100644
--- a/lib/domain/media/rights.dart
+++ b/lib/domain/media/rights.dart
@@ -12,7 +12,7 @@ class Rights {
       return null;
     }
     return Rights(
-      status: element.getAttribute("status"),
+      status: element.getAttribute('status'),
     );
   }
 }
diff --git a/lib/domain/media/scene.dart b/lib/domain/media/scene.dart
index 1336dc9..19e730e 100644
--- a/lib/domain/media/scene.dart
+++ b/lib/domain/media/scene.dart
@@ -19,10 +19,10 @@ class Scene {
       return null;
     }
     return Scene(
-      title: findElementOrNull(element, "sceneTitle")?.text,
-      description: findElementOrNull(element, "sceneDescription")?.text,
-      startTime: findElementOrNull(element, "sceneStartTime")?.text,
-      endTime: findElementOrNull(element, "sceneEndTime")?.text,
+      title: findElementOrNull(element, 'sceneTitle')?.text,
+      description: findElementOrNull(element, 'sceneDescription')?.text,
+      startTime: findElementOrNull(element, 'sceneStartTime')?.text,
+      endTime: findElementOrNull(element, 'sceneEndTime')?.text,
     );
   }
 }
diff --git a/lib/domain/media/star_rating.dart b/lib/domain/media/star_rating.dart
index 9fc456b..9348a5a 100644
--- a/lib/domain/media/star_rating.dart
+++ b/lib/domain/media/star_rating.dart
@@ -15,10 +15,10 @@ class StarRating {
 
   factory StarRating.parse(XmlElement element) {
     return StarRating(
-      average: double.tryParse(element.getAttribute("average") ?? "0"),
-      count: int.tryParse(element.getAttribute("count") ?? "0"),
-      min: int.tryParse(element.getAttribute("min") ?? "0"),
-      max: int.tryParse(element.getAttribute("max") ?? "0"),
+      average: double.tryParse(element.getAttribute('average') ?? '0'),
+      count: int.tryParse(element.getAttribute('count') ?? '0'),
+      min: int.tryParse(element.getAttribute('min') ?? '0'),
+      max: int.tryParse(element.getAttribute('max') ?? '0'),
     );
   }
 }
diff --git a/lib/domain/media/statistics.dart b/lib/domain/media/statistics.dart
index d30b025..01ade1e 100644
--- a/lib/domain/media/statistics.dart
+++ b/lib/domain/media/statistics.dart
@@ -11,8 +11,8 @@ class Statistics {
 
   factory Statistics.parse(XmlElement element) {
     return Statistics(
-      views: int.tryParse(element.getAttribute("views") ?? "0"),
-      favorites: int.tryParse(element.getAttribute("favorites") ?? "0"),
+      views: int.tryParse(element.getAttribute('views') ?? '0'),
+      favorites: int.tryParse(element.getAttribute('favorites') ?? '0'),
     );
   }
 }
diff --git a/lib/domain/media/status.dart b/lib/domain/media/status.dart
index 17200ac..a5f0b15 100644
--- a/lib/domain/media/status.dart
+++ b/lib/domain/media/status.dart
@@ -14,8 +14,8 @@ class Status {
       return null;
     }
     return Status(
-      state: element.getAttribute("state"),
-      reason: element.getAttribute("reason"),
+      state: element.getAttribute('state'),
+      reason: element.getAttribute('reason'),
     );
   }
 }
diff --git a/lib/domain/media/tags.dart b/lib/domain/media/tags.dart
index 3617a0a..b3f747d 100644
--- a/lib/domain/media/tags.dart
+++ b/lib/domain/media/tags.dart
@@ -15,7 +15,7 @@ class Tags {
     }
     return Tags(
       tags: element.text,
-      weight: int.tryParse(element.getAttribute("weight") ?? "1"),
+      weight: int.tryParse(element.getAttribute('weight') ?? '1'),
     );
   }
 }
diff --git a/lib/domain/media/text.dart b/lib/domain/media/text.dart
index 702e934..58e8d21 100644
--- a/lib/domain/media/text.dart
+++ b/lib/domain/media/text.dart
@@ -20,10 +20,10 @@ class Text {
       return null;
     }
     return Text(
-      type: element.getAttribute("type"),
-      lang: element.getAttribute("lang"),
-      start: element.getAttribute("start"),
-      end: element.getAttribute("end"),
+      type: element.getAttribute('type'),
+      lang: element.getAttribute('lang'),
+      start: element.getAttribute('start'),
+      end: element.getAttribute('end'),
       value: element.text,
     );
   }
diff --git a/lib/domain/media/thumbnail.dart b/lib/domain/media/thumbnail.dart
index 0c3f31c..85d81e7 100644
--- a/lib/domain/media/thumbnail.dart
+++ b/lib/domain/media/thumbnail.dart
@@ -15,10 +15,10 @@ class Thumbnail {
 
   factory Thumbnail.parse(XmlElement element) {
     return Thumbnail(
-      url: element.getAttribute("url"),
-      width: element.getAttribute("width"),
-      height: element.getAttribute("height"),
-      time: element.getAttribute("time"),
+      url: element.getAttribute('url'),
+      width: element.getAttribute('width'),
+      height: element.getAttribute('height'),
+      time: element.getAttribute('time'),
     );
   }
 }
diff --git a/lib/domain/media/title.dart b/lib/domain/media/title.dart
index 49482d6..9968bce 100644
--- a/lib/domain/media/title.dart
+++ b/lib/domain/media/title.dart
@@ -14,7 +14,7 @@ class Title {
       return null;
     }
     return Title(
-      type: element.getAttribute("type"),
+      type: element.getAttribute('type'),
       value: element.text,
     );
   }
diff --git a/lib/domain/rss_category.dart b/lib/domain/rss_category.dart
index 845a837..a3ca7d7 100644
--- a/lib/domain/rss_category.dart
+++ b/lib/domain/rss_category.dart
@@ -10,7 +10,7 @@ class RssCategory {
     if (element == null) {
       return null;
     }
-    var domain = element.getAttribute("domain");
+    var domain = element.getAttribute('domain');
     var value = element.text;
 
     return RssCategory(domain, value);
diff --git a/lib/domain/rss_cloud.dart b/lib/domain/rss_cloud.dart
index 74d8b6a..73f3c32 100644
--- a/lib/domain/rss_cloud.dart
+++ b/lib/domain/rss_cloud.dart
@@ -19,11 +19,11 @@ class RssCloud {
     if (node == null) {
       return null;
     }
-    var domain = node.getAttribute("domain");
-    var port = node.getAttribute("port");
-    var path = node.getAttribute("path");
-    var registerProcedure = node.getAttribute("registerProcedure");
-    var protocol = node.getAttribute("protocol");
+    var domain = node.getAttribute('domain');
+    var port = node.getAttribute('port');
+    var path = node.getAttribute('path');
+    var registerProcedure = node.getAttribute('registerProcedure');
+    var protocol = node.getAttribute('protocol');
     return RssCloud(domain, port, path, registerProcedure, protocol);
   }
 }
diff --git a/lib/domain/rss_enclosure.dart b/lib/domain/rss_enclosure.dart
index 4b125e2..dd303c7 100644
--- a/lib/domain/rss_enclosure.dart
+++ b/lib/domain/rss_enclosure.dart
@@ -11,9 +11,9 @@ class RssEnclosure {
     if (element == null) {
       return null;
     }
-    var url = element.getAttribute("url");
-    var type = element.getAttribute("type");
-    var length = int.tryParse(element.getAttribute("length") ?? "0");
+    var url = element.getAttribute('url');
+    var type = element.getAttribute('type');
+    var length = int.tryParse(element.getAttribute('length') ?? '0');
     return RssEnclosure(url, type, length);
   }
 }
diff --git a/lib/domain/rss_feed.dart b/lib/domain/rss_feed.dart
index 880f8e3..2235fe4 100644
--- a/lib/domain/rss_feed.dart
+++ b/lib/domain/rss_feed.dart
@@ -62,45 +62,45 @@ class RssFeed {
     var document = XmlDocument.parse(xmlString);
     XmlElement channelElement;
     try {
-      channelElement = document.findAllElements("channel").first;
+      channelElement = document.findAllElements('channel').first;
     } on StateError {
-      throw ArgumentError("channel not found");
+      throw ArgumentError('channel not found');
     }
 
     return RssFeed(
-      title: findElementOrNull(channelElement, "title")?.text,
-      author: findElementOrNull(channelElement, "author")?.text,
-      description: findElementOrNull(channelElement, "description")?.text,
-      link: findElementOrNull(channelElement, "link")?.text,
-      items: channelElement.findElements("item").map((element) {
+      title: findElementOrNull(channelElement, 'title')?.text,
+      author: findElementOrNull(channelElement, 'author')?.text,
+      description: findElementOrNull(channelElement, 'description')?.text,
+      link: findElementOrNull(channelElement, 'link')?.text,
+      items: channelElement.findElements('item').map((element) {
         return RssItem.parse(element);
       }).toList(),
-      image: RssImage.parse(findElementOrNull(channelElement, "image")),
-      cloud: RssCloud.parse(findElementOrNull(channelElement, "cloud")),
-      categories: channelElement.findElements("category").map((element) {
+      image: RssImage.parse(findElementOrNull(channelElement, 'image')),
+      cloud: RssCloud.parse(findElementOrNull(channelElement, 'cloud')),
+      categories: channelElement.findElements('category').map((element) {
         return RssCategory.parse(element);
       }).toList(),
-      skipDays: findElementOrNull(channelElement, "skipDays")
-              ?.findAllElements("day")
+      skipDays: findElementOrNull(channelElement, 'skipDays')
+              ?.findAllElements('day')
               ?.map((element) {
             return element.text;
           })?.toList() ??
           [],
-      skipHours: findElementOrNull(channelElement, "skipHours")
-              ?.findAllElements("hour")
+      skipHours: findElementOrNull(channelElement, 'skipHours')
+              ?.findAllElements('hour')
               ?.map((element) {
-            return int.tryParse(element.text ?? "0");
+            return int.tryParse(element.text ?? '0');
           })?.toList() ??
           [],
-      lastBuildDate: findElementOrNull(channelElement, "lastBuildDate")?.text,
-      language: findElementOrNull(channelElement, "language")?.text,
-      generator: findElementOrNull(channelElement, "generator")?.text,
-      copyright: findElementOrNull(channelElement, "copyright")?.text,
-      docs: findElementOrNull(channelElement, "docs")?.text,
-      managingEditor: findElementOrNull(channelElement, "managingEditor")?.text,
-      rating: findElementOrNull(channelElement, "rating")?.text,
-      webMaster: findElementOrNull(channelElement, "webMaster")?.text,
-      ttl: int.tryParse(findElementOrNull(channelElement, "ttl")?.text ?? "0"),
+      lastBuildDate: findElementOrNull(channelElement, 'lastBuildDate')?.text,
+      language: findElementOrNull(channelElement, 'language')?.text,
+      generator: findElementOrNull(channelElement, 'generator')?.text,
+      copyright: findElementOrNull(channelElement, 'copyright')?.text,
+      docs: findElementOrNull(channelElement, 'docs')?.text,
+      managingEditor: findElementOrNull(channelElement, 'managingEditor')?.text,
+      rating: findElementOrNull(channelElement, 'rating')?.text,
+      webMaster: findElementOrNull(channelElement, 'webMaster')?.text,
+      ttl: int.tryParse(findElementOrNull(channelElement, 'ttl')?.text ?? '0'),
       dc: DublinCore.parse(channelElement),
       itunes: RssItunes.parse(channelElement),
     );
diff --git a/lib/domain/rss_image.dart b/lib/domain/rss_image.dart
index 447b628..9ed4e33 100644
--- a/lib/domain/rss_image.dart
+++ b/lib/domain/rss_image.dart
@@ -12,9 +12,9 @@ class RssImage {
     if (element == null) {
       return null;
     }
-    var title = findElementOrNull(element, "title")?.text;
-    var url = findElementOrNull(element, "url")?.text;
-    var link = findElementOrNull(element, "link")?.text;
+    var title = findElementOrNull(element, 'title')?.text;
+    var url = findElementOrNull(element, 'url')?.text;
+    var link = findElementOrNull(element, 'link')?.text;
 
     return RssImage(title, url, link);
   }
diff --git a/lib/domain/rss_item.dart b/lib/domain/rss_item.dart
index edecd9b..534399e 100644
--- a/lib/domain/rss_item.dart
+++ b/lib/domain/rss_item.dart
@@ -45,20 +45,20 @@ class RssItem {
 
   factory RssItem.parse(XmlElement element) {
     return RssItem(
-      title: findElementOrNull(element, "title")?.text,
-      description: findElementOrNull(element, "description")?.text,
-      link: findElementOrNull(element, "link")?.text,
-      categories: element.findElements("category").map((element) {
+      title: findElementOrNull(element, 'title')?.text,
+      description: findElementOrNull(element, 'description')?.text,
+      link: findElementOrNull(element, 'link')?.text,
+      categories: element.findElements('category').map((element) {
         return RssCategory.parse(element);
       }).toList(),
-      guid: findElementOrNull(element, "guid")?.text,
-      pubDate: parseDateTime(findElementOrNull(element, "pubDate")?.text),
-      author: findElementOrNull(element, "author")?.text,
-      comments: findElementOrNull(element, "comments")?.text,
-      source: RssSource.parse(findElementOrNull(element, "source")),
-      content: RssContent.parse(findElementOrNull(element, "content:encoded")),
+      guid: findElementOrNull(element, 'guid')?.text,
+      pubDate: parseDateTime(findElementOrNull(element, 'pubDate')?.text),
+      author: findElementOrNull(element, 'author')?.text,
+      comments: findElementOrNull(element, 'comments')?.text,
+      source: RssSource.parse(findElementOrNull(element, 'source')),
+      content: RssContent.parse(findElementOrNull(element, 'content:encoded')),
       media: Media.parse(element),
-      enclosure: RssEnclosure.parse(findElementOrNull(element, "enclosure")),
+      enclosure: RssEnclosure.parse(findElementOrNull(element, 'enclosure')),
       dc: DublinCore.parse(element),
       itunes: RssItemItunes.parse(element),
     );
diff --git a/lib/domain/rss_item_itunes.dart b/lib/domain/rss_item_itunes.dart
index 19f1c12..0c94044 100644
--- a/lib/domain/rss_item_itunes.dart
+++ b/lib/domain/rss_item_itunes.dart
@@ -40,31 +40,31 @@ class RssItemItunes {
     if (element == null) {
       return null;
     }
-    var episodeStr = findElementOrNull(element, "itunes:episode")?.text?.trim();
-    var seasonStr = findElementOrNull(element, "itunes:season")?.text?.trim();
+    var episodeStr = findElementOrNull(element, 'itunes:episode')?.text?.trim();
+    var seasonStr = findElementOrNull(element, 'itunes:season')?.text?.trim();
     var durationStr =
-        findElementOrNull(element, "itunes:duration")?.text?.trim();
+        findElementOrNull(element, 'itunes:duration')?.text?.trim();
 
     return RssItemItunes(
-      title: findElementOrNull(element, "itunes:title")?.text?.trim(),
+      title: findElementOrNull(element, 'itunes:title')?.text?.trim(),
       episode: episodeStr == null ? null : int.parse(episodeStr),
       season: seasonStr == null ? null : int.parse(seasonStr),
       duration: durationStr == null ? null : parseDuration(durationStr),
       episodeType: newRssItunesEpisodeType(
-          findElementOrNull(element, "itunes:episodeType")),
-      author: findElementOrNull(element, "itunes:author")?.text?.trim(),
-      summary: findElementOrNull(element, "itunes:summary")?.text?.trim(),
-      explicit: parseBoolLiteral(element, "itunes:explicit"),
-      subtitle: findElementOrNull(element, "itunes:subtitle")?.text?.trim(),
-      keywords: findElementOrNull(element, "itunes:keywords")
+          findElementOrNull(element, 'itunes:episodeType')),
+      author: findElementOrNull(element, 'itunes:author')?.text?.trim(),
+      summary: findElementOrNull(element, 'itunes:summary')?.text?.trim(),
+      explicit: parseBoolLiteral(element, 'itunes:explicit'),
+      subtitle: findElementOrNull(element, 'itunes:subtitle')?.text?.trim(),
+      keywords: findElementOrNull(element, 'itunes:keywords')
           ?.text
-          ?.split(",")
+          ?.split(',')
           ?.map((keyword) => keyword.trim())
           ?.toList(),
-      image: RssItunesImage.parse(findElementOrNull(element, "itunes:image")),
+      image: RssItunesImage.parse(findElementOrNull(element, 'itunes:image')),
       category: RssItunesCategory.parse(
-          findElementOrNull(element, "itunes:category")),
-      block: parseBoolLiteral(element, "itunes:block"),
+          findElementOrNull(element, 'itunes:category')),
+      block: parseBoolLiteral(element, 'itunes:block'),
     );
   }
 }
diff --git a/lib/domain/rss_itunes.dart b/lib/domain/rss_itunes.dart
index e4e7685..af0b9e9 100644
--- a/lib/domain/rss_itunes.dart
+++ b/lib/domain/rss_itunes.dart
@@ -42,26 +42,26 @@ class RssItunes {
       return null;
     }
     return RssItunes(
-      author: findElementOrNull(element, "itunes:author")?.text?.trim(),
-      summary: findElementOrNull(element, "itunes:summary")?.text?.trim(),
-      explicit: parseBoolLiteral(element, "itunes:explicit"),
-      title: findElementOrNull(element, "itunes:title")?.text?.trim(),
-      subtitle: findElementOrNull(element, "itunes:subtitle")?.text?.trim(),
-      owner: RssItunesOwner.parse(findElementOrNull(element, "itunes:owner")),
-      keywords: findElementOrNull(element, "itunes:keywords")
+      author: findElementOrNull(element, 'itunes:author')?.text?.trim(),
+      summary: findElementOrNull(element, 'itunes:summary')?.text?.trim(),
+      explicit: parseBoolLiteral(element, 'itunes:explicit'),
+      title: findElementOrNull(element, 'itunes:title')?.text?.trim(),
+      subtitle: findElementOrNull(element, 'itunes:subtitle')?.text?.trim(),
+      owner: RssItunesOwner.parse(findElementOrNull(element, 'itunes:owner')),
+      keywords: findElementOrNull(element, 'itunes:keywords')
           ?.text
-          ?.split(",")
+          ?.split(',')
           ?.map((keyword) => keyword.trim())
           ?.toList(),
-      image: RssItunesImage.parse(findElementOrNull(element, "itunes:image")),
-      categories: findAllDirectElementsOrNull(element, "itunes:category")
+      image: RssItunesImage.parse(findElementOrNull(element, 'itunes:image')),
+      categories: findAllDirectElementsOrNull(element, 'itunes:category')
           .map((ele) => RssItunesCategory.parse(ele))
           .toList(),
-      type: newRssItunesType(findElementOrNull(element, "itunes:type")),
+      type: newRssItunesType(findElementOrNull(element, 'itunes:type')),
       newFeedUrl:
-          findElementOrNull(element, "itunes:new-feed-url")?.text?.trim(),
-      block: parseBoolLiteral(element, "itunes:block"),
-      complete: parseBoolLiteral(element, "itunes:complete"),
+          findElementOrNull(element, 'itunes:new-feed-url')?.text?.trim(),
+      block: parseBoolLiteral(element, 'itunes:block'),
+      complete: parseBoolLiteral(element, 'itunes:complete'),
     );
   }
 }
diff --git a/lib/domain/rss_itunes_category.dart b/lib/domain/rss_itunes_category.dart
index b79f339..f6b7334 100644
--- a/lib/domain/rss_itunes_category.dart
+++ b/lib/domain/rss_itunes_category.dart
@@ -11,14 +11,15 @@ class RssItunesCategory {
 
     Iterable<XmlElement> subCategories;
     try {
-      subCategories = element.findElements("itunes:category");
+      subCategories = element.findElements('itunes:category');
     } on StateError {
       subCategories = null;
     }
     return RssItunesCategory(
-      category: element.getAttribute("text")?.trim(),
-      subCategories:
-          subCategories?.map((ele) => ele.getAttribute("text")?.trim())?.toList(),
+      category: element.getAttribute('text')?.trim(),
+      subCategories: subCategories
+          ?.map((ele) => ele.getAttribute('text')?.trim())
+          ?.toList(),
     );
   }
 }
diff --git a/lib/domain/rss_itunes_episode_type.dart b/lib/domain/rss_itunes_episode_type.dart
index 30e639d..ffbf960 100644
--- a/lib/domain/rss_itunes_episode_type.dart
+++ b/lib/domain/rss_itunes_episode_type.dart
@@ -1,17 +1,17 @@
 import 'package:xml/xml.dart';
 
-enum RssItunesEpisodeType {full, trailer, bonus}
+enum RssItunesEpisodeType { full, trailer, bonus }
 
 RssItunesEpisodeType newRssItunesEpisodeType(XmlElement element) {
   // "full" is default type
   if (element == null) return RssItunesEpisodeType.full;
 
   switch (element.text) {
-    case "full":
+    case 'full':
       return RssItunesEpisodeType.full;
-    case "trailer":
+    case 'trailer':
       return RssItunesEpisodeType.trailer;
-    case "bonus":
+    case 'bonus':
       return RssItunesEpisodeType.bonus;
     default:
       return null;
diff --git a/lib/domain/rss_itunes_image.dart b/lib/domain/rss_itunes_image.dart
index 7b2ef2f..8328979 100644
--- a/lib/domain/rss_itunes_image.dart
+++ b/lib/domain/rss_itunes_image.dart
@@ -8,7 +8,7 @@ class RssItunesImage {
   factory RssItunesImage.parse(XmlElement element) {
     if (element == null) return null;
     return RssItunesImage(
-      href: element.getAttribute("href")?.trim(),
+      href: element.getAttribute('href')?.trim(),
     );
   }
 }
diff --git a/lib/domain/rss_itunes_owner.dart b/lib/domain/rss_itunes_owner.dart
index 2d72294..e0bc605 100644
--- a/lib/domain/rss_itunes_owner.dart
+++ b/lib/domain/rss_itunes_owner.dart
@@ -11,8 +11,8 @@ class RssItunesOwner {
   factory RssItunesOwner.parse(XmlElement element) {
     if (element == null) return null;
     return RssItunesOwner(
-      name: findElementOrNull(element, "itunes:name")?.text?.trim(),
-      email: findElementOrNull(element, "itunes:email")?.text?.trim(),
+      name: findElementOrNull(element, 'itunes:name')?.text?.trim(),
+      email: findElementOrNull(element, 'itunes:email')?.text?.trim(),
     );
   }
 }
diff --git a/lib/domain/rss_itunes_type.dart b/lib/domain/rss_itunes_type.dart
index b2cb031..b5c846f 100644
--- a/lib/domain/rss_itunes_type.dart
+++ b/lib/domain/rss_itunes_type.dart
@@ -3,13 +3,13 @@ import 'package:xml/xml.dart';
 enum RssItunesType { episodic, serial }
 
 RssItunesType newRssItunesType(XmlElement element) {
-  // "episodic" is default type
+  // 'episodic' is default type
   if (element == null) return RssItunesType.episodic;
 
   switch (element.text) {
-    case "episodic":
+    case 'episodic':
       return RssItunesType.episodic;
-    case "serial":
+    case 'serial':
       return RssItunesType.serial;
     default:
       return null;
diff --git a/lib/domain/rss_source.dart b/lib/domain/rss_source.dart
index 6d82be8..056fe7b 100644
--- a/lib/domain/rss_source.dart
+++ b/lib/domain/rss_source.dart
@@ -10,7 +10,7 @@ class RssSource {
     if (element == null) {
       return null;
     }
-    var url = element.getAttribute("url");
+    var url = element.getAttribute('url');
     var value = element.text;
 
     return RssSource(url, value);
diff --git a/lib/util/xml.dart b/lib/util/xml.dart
index 179926c..113a8c1 100644
--- a/lib/util/xml.dart
+++ b/lib/util/xml.dart
@@ -23,6 +23,5 @@ List<XmlElement> findAllDirectElementsOrNull(XmlElement element, String name,
 bool parseBoolLiteral(XmlElement element, String tagName) {
   var v = findElementOrNull(element, tagName)?.text?.toLowerCase()?.trim();
   if (v == null) return null;
-  return ["yes", "true"].contains(v);
+  return ['yes', 'true'].contains(v);
 }
-
diff --git a/test/atom_test.dart b/test/atom_test.dart
index f3b9c12..1cd24fc 100644
--- a/test/atom_test.dart
+++ b/test/atom_test.dart
@@ -5,95 +5,95 @@ import 'package:test/test.dart';
 import 'package:webfeed/webfeed.dart';
 
 void main() {
-  test("parse Invalid.xml", () {
-    var xmlString = File("test/xml/Invalid.xml").readAsStringSync();
+  test('parse Invalid.xml', () {
+    var xmlString = File('test/xml/Invalid.xml').readAsStringSync();
 
     try {
       AtomFeed.parse(xmlString);
-      fail("Should throw Argument Error");
+      fail('Should throw Argument Error');
     } on ArgumentError {}
   });
 
-  test("parse Atom.xml", () {
-    var xmlString = File("test/xml/Atom.xml").readAsStringSync();
+  test('parse Atom.xml', () {
+    var xmlString = File('test/xml/Atom.xml').readAsStringSync();
 
     var feed = AtomFeed.parse(xmlString);
 
-    expect(feed.id, "foo-bar-id");
-    expect(feed.title, "Foo bar news");
+    expect(feed.id, 'foo-bar-id');
+    expect(feed.title, 'Foo bar news');
     expect(feed.updated, DateTime.utc(2018, 4, 6, 13, 2, 46));
 
     expect(feed.links.length, 2);
-    expect(feed.links.first.rel, "foo");
-    expect(feed.links.first.type, "text/html");
-    expect(feed.links.first.hreflang, "en");
-    expect(feed.links.first.href, "http://foo.bar.news/");
-    expect(feed.links.first.title, "Foo bar news html");
+    expect(feed.links.first.rel, 'foo');
+    expect(feed.links.first.type, 'text/html');
+    expect(feed.links.first.hreflang, 'en');
+    expect(feed.links.first.href, 'http://foo.bar.news/');
+    expect(feed.links.first.title, 'Foo bar news html');
     expect(feed.links.first.length, 1000);
 
     expect(feed.authors.length, 2);
-    expect(feed.authors.first.name, "Alice");
-    expect(feed.authors.first.uri, "http://foo.bar.news/people/alice");
-    expect(feed.authors.first.email, "alice@foo.bar.news");
+    expect(feed.authors.first.name, 'Alice');
+    expect(feed.authors.first.uri, 'http://foo.bar.news/people/alice');
+    expect(feed.authors.first.email, 'alice@foo.bar.news');
 
     expect(feed.contributors.length, 2);
-    expect(feed.contributors.first.name, "Charlie");
-    expect(feed.contributors.first.uri, "http://foo.bar.news/people/charlie");
-    expect(feed.contributors.first.email, "charlie@foo.bar.news");
+    expect(feed.contributors.first.name, 'Charlie');
+    expect(feed.contributors.first.uri, 'http://foo.bar.news/people/charlie');
+    expect(feed.contributors.first.email, 'charlie@foo.bar.news');
 
     expect(feed.categories.length, 2);
-    expect(feed.categories.first.term, "foo category");
-    expect(feed.categories.first.scheme, "this-is-foo-scheme");
-    expect(feed.categories.first.label, "this is foo label");
+    expect(feed.categories.first.term, 'foo category');
+    expect(feed.categories.first.scheme, 'this-is-foo-scheme');
+    expect(feed.categories.first.label, 'this is foo label');
 
-    expect(feed.generator.uri, "http://foo.bar.news/generator");
-    expect(feed.generator.version, "1.0");
-    expect(feed.generator.value, "Foo bar generator");
+    expect(feed.generator.uri, 'http://foo.bar.news/generator');
+    expect(feed.generator.version, '1.0');
+    expect(feed.generator.value, 'Foo bar generator');
 
-    expect(feed.icon, "http://foo.bar.news/icon.png");
-    expect(feed.logo, "http://foo.bar.news/logo.png");
-    expect(feed.subtitle, "This is subtitle");
+    expect(feed.icon, 'http://foo.bar.news/icon.png');
+    expect(feed.logo, 'http://foo.bar.news/logo.png');
+    expect(feed.subtitle, 'This is subtitle');
 
     expect(feed.items.length, 2);
     var item = feed.items.first;
-    expect(item.id, "foo-bar-entry-id-1");
-    expect(item.title, "Foo bar item 1");
+    expect(item.id, 'foo-bar-entry-id-1');
+    expect(item.title, 'Foo bar item 1');
     expect(item.updated, DateTime.utc(2018, 4, 6, 13, 2, 40));
 
     expect(item.authors.length, 2);
-    expect(item.authors.first.name, "Ellie");
-    expect(item.authors.first.uri, "http://foo.bar.news/people/ellie");
-    expect(item.authors.first.email, "ellie@foo.bar.news");
+    expect(item.authors.first.name, 'Ellie');
+    expect(item.authors.first.uri, 'http://foo.bar.news/people/ellie');
+    expect(item.authors.first.email, 'ellie@foo.bar.news');
 
     expect(item.links.length, 2);
-    expect(item.links.first.rel, "foo entry");
-    expect(item.links.first.type, "text/html");
-    expect(item.links.first.hreflang, "en");
-    expect(item.links.first.href, "http://foo.bar.news/entry");
-    expect(item.links.first.title, "Foo bar news html");
+    expect(item.links.first.rel, 'foo entry');
+    expect(item.links.first.type, 'text/html');
+    expect(item.links.first.hreflang, 'en');
+    expect(item.links.first.href, 'http://foo.bar.news/entry');
+    expect(item.links.first.title, 'Foo bar news html');
     expect(item.links.first.length, 1000);
 
     expect(item.categories.length, 2);
-    expect(item.categories.first.term, "foo entry category");
-    expect(item.categories.first.scheme, "this-is-foo-entry-scheme");
-    expect(item.categories.first.label, "this is foo entry label");
+    expect(item.categories.first.term, 'foo entry category');
+    expect(item.categories.first.scheme, 'this-is-foo-entry-scheme');
+    expect(item.categories.first.label, 'this is foo entry label');
 
     expect(item.contributors.length, 2);
-    expect(item.contributors.first.name, "Gin");
-    expect(item.contributors.first.uri, "http://foo.bar.news/people/gin");
-    expect(item.contributors.first.email, "gin@foo.bar.news");
-
-    expect(item.published, "2018-04-06T13:02:49Z");
-    expect(item.summary, "This is summary 1");
-    expect(item.content, "This is content 1");
-    expect(item.rights, "This is rights 1");
+    expect(item.contributors.first.name, 'Gin');
+    expect(item.contributors.first.uri, 'http://foo.bar.news/people/gin');
+    expect(item.contributors.first.email, 'gin@foo.bar.news');
+
+    expect(item.published, '2018-04-06T13:02:49Z');
+    expect(item.summary, 'This is summary 1');
+    expect(item.content, 'This is content 1');
+    expect(item.rights, 'This is rights 1');
   });
-  test("parse Atom-Media.xml", () {
-    var xmlString = File("test/xml/Atom-Media.xml").readAsStringSync();
+  test('parse Atom-Media.xml', () {
+    var xmlString = File('test/xml/Atom-Media.xml').readAsStringSync();
 
     var feed = AtomFeed.parse(xmlString);
-    expect(feed.id, "foo-bar-id");
-    expect(feed.title, "Foo bar news");
+    expect(feed.id, 'foo-bar-id');
+    expect(feed.title, 'Foo bar news');
     expect(feed.updated, DateTime.utc(2018, 4, 6, 13, 2, 46));
 
     expect(feed.items.length, 1);
@@ -101,17 +101,17 @@ void main() {
     var item = feed.items.first;
     expect(item.media.group.contents.length, 5);
     expect(item.media.group.credits.length, 2);
-    expect(item.media.group.category.value, "music/artist name/album/song");
-    expect(item.media.group.rating.value, "nonadult");
+    expect(item.media.group.category.value, 'music/artist name/album/song');
+    expect(item.media.group.rating.value, 'nonadult');
 
     expect(item.media.contents.length, 2);
     var mediaContent = item.media.contents.first;
-    expect(mediaContent.url, "http://www.foo.com/video.mov");
-    expect(mediaContent.type, "video/quicktime");
+    expect(mediaContent.url, 'http://www.foo.com/video.mov');
+    expect(mediaContent.type, 'video/quicktime');
     expect(mediaContent.fileSize, 2000);
-    expect(mediaContent.medium, "video");
+    expect(mediaContent.medium, 'video');
     expect(mediaContent.isDefault, true);
-    expect(mediaContent.expression, "full");
+    expect(mediaContent.expression, 'full');
     expect(mediaContent.bitrate, 128);
     expect(mediaContent.framerate, 25);
     expect(mediaContent.samplingrate, 44.1);
@@ -119,54 +119,54 @@ void main() {
 
     expect(item.media.credits.length, 2);
     var mediaCredit = item.media.credits.first;
-    expect(mediaCredit.role, "owner1");
-    expect(mediaCredit.scheme, "urn:yvs");
-    expect(mediaCredit.value, "copyright holder of the entity");
+    expect(mediaCredit.role, 'owner1');
+    expect(mediaCredit.scheme, 'urn:yvs');
+    expect(mediaCredit.value, 'copyright holder of the entity');
 
     expect(item.media.category.scheme,
-        "http://search.yahoo.com/mrss/category_ schema");
-    expect(item.media.category.label, "Music");
-    expect(item.media.category.value, "music/artist/album/song");
+        'http://search.yahoo.com/mrss/category_ schema');
+    expect(item.media.category.label, 'Music');
+    expect(item.media.category.value, 'music/artist/album/song');
 
-    expect(item.media.rating.scheme, "urn:simple");
-    expect(item.media.rating.value, "adult");
+    expect(item.media.rating.scheme, 'urn:simple');
+    expect(item.media.rating.value, 'adult');
 
-    expect(item.media.title.type, "plain");
+    expect(item.media.title.type, 'plain');
     expect(item.media.title.value, "The Judy's -- The Moo Song");
 
-    expect(item.media.description.type, "plain");
+    expect(item.media.description.type, 'plain');
     expect(item.media.description.value,
-        "This was some really bizarre band I listened to as a young lad.");
+        'This was some really bizarre band I listened to as a young lad.');
 
-    expect(item.media.keywords, "kitty, cat, big dog, yarn, fluffy");
+    expect(item.media.keywords, 'kitty, cat, big dog, yarn, fluffy');
 
     expect(item.media.thumbnails.length, 2);
     var mediaThumbnail = item.media.thumbnails.first;
-    expect(mediaThumbnail.url, "http://www.foo.com/keyframe1.jpg");
-    expect(mediaThumbnail.width, "75");
-    expect(mediaThumbnail.height, "50");
-    expect(mediaThumbnail.time, "12:05:01.123");
+    expect(mediaThumbnail.url, 'http://www.foo.com/keyframe1.jpg');
+    expect(mediaThumbnail.width, '75');
+    expect(mediaThumbnail.height, '50');
+    expect(mediaThumbnail.time, '12:05:01.123');
 
-    expect(item.media.hash.algo, "md5");
-    expect(item.media.hash.value, "dfdec888b72151965a34b4b59031290a");
+    expect(item.media.hash.algo, 'md5');
+    expect(item.media.hash.value, 'dfdec888b72151965a34b4b59031290a');
 
-    expect(item.media.player.url, "http://www.foo.com/player?id=1111");
+    expect(item.media.player.url, 'http://www.foo.com/player?id=1111');
     expect(item.media.player.width, 400);
     expect(item.media.player.height, 200);
-    expect(item.media.player.value, "");
+    expect(item.media.player.value, '');
 
-    expect(item.media.copyright.url, "http://blah.com/additional-info.html");
-    expect(item.media.copyright.value, "2005 FooBar Media");
+    expect(item.media.copyright.url, 'http://blah.com/additional-info.html');
+    expect(item.media.copyright.value, '2005 FooBar Media');
 
-    expect(item.media.text.type, "plain");
-    expect(item.media.text.lang, "en");
-    expect(item.media.text.start, "00:00:03.000");
-    expect(item.media.text.end, "00:00:10.000");
-    expect(item.media.text.value, " Oh, say, can you see");
+    expect(item.media.text.type, 'plain');
+    expect(item.media.text.lang, 'en');
+    expect(item.media.text.start, '00:00:03.000');
+    expect(item.media.text.end, '00:00:10.000');
+    expect(item.media.text.value, ' Oh, say, can you see');
 
-    expect(item.media.restriction.relationship, "allow");
-    expect(item.media.restriction.type, "country");
-    expect(item.media.restriction.value, "au us");
+    expect(item.media.restriction.relationship, 'allow');
+    expect(item.media.restriction.type, 'country');
+    expect(item.media.restriction.value, 'au us');
 
     expect(item.media.community.starRating.average, 3.5);
     expect(item.media.community.starRating.count, 20);
@@ -174,58 +174,58 @@ void main() {
     expect(item.media.community.starRating.max, 10);
     expect(item.media.community.statistics.views, 5);
     expect(item.media.community.statistics.favorites, 4);
-    expect(item.media.community.tags.tags, "news: 5, abc:3");
+    expect(item.media.community.tags.tags, 'news: 5, abc:3');
     expect(item.media.community.tags.weight, 1);
 
     expect(item.media.comments.length, 2);
-    expect(item.media.comments.first, "comment1");
-    expect(item.media.comments.last, "comment2");
+    expect(item.media.comments.first, 'comment1');
+    expect(item.media.comments.last, 'comment2');
 
-    expect(item.media.embed.url, "http://www.foo.com/player.swf");
+    expect(item.media.embed.url, 'http://www.foo.com/player.swf');
     expect(item.media.embed.width, 512);
     expect(item.media.embed.height, 323);
     expect(item.media.embed.params.length, 5);
-    expect(item.media.embed.params.first.name, "type");
+    expect(item.media.embed.params.first.name, 'type');
     expect(
-        item.media.embed.params.first.value, "application/x-shockwave-flash");
+        item.media.embed.params.first.value, 'application/x-shockwave-flash');
 
     expect(item.media.responses.length, 2);
-    expect(item.media.responses.first, "http://www.response1.com");
-    expect(item.media.responses.last, "http://www.response2.com");
+    expect(item.media.responses.first, 'http://www.response1.com');
+    expect(item.media.responses.last, 'http://www.response2.com');
 
     expect(item.media.backLinks.length, 2);
-    expect(item.media.backLinks.first, "http://www.backlink1.com");
-    expect(item.media.backLinks.last, "http://www.backlink2.com");
+    expect(item.media.backLinks.first, 'http://www.backlink1.com');
+    expect(item.media.backLinks.last, 'http://www.backlink2.com');
 
-    expect(item.media.status.state, "active");
+    expect(item.media.status.state, 'active');
     expect(item.media.status.reason, null);
 
     expect(item.media.prices.length, 2);
     expect(item.media.prices.first.price, 19.99);
-    expect(item.media.prices.first.type, "rent");
+    expect(item.media.prices.first.type, 'rent');
     expect(
-        item.media.prices.first.info, "http://www.dummy.jp/package_info.html");
-    expect(item.media.prices.first.currency, "EUR");
+        item.media.prices.first.info, 'http://www.dummy.jp/package_info.html');
+    expect(item.media.prices.first.currency, 'EUR');
 
-    expect(item.media.license.type, "text/html");
-    expect(item.media.license.href, "http://www.licensehost.com/license");
-    expect(item.media.license.value, " Sample license for a video");
+    expect(item.media.license.type, 'text/html');
+    expect(item.media.license.href, 'http://www.licensehost.com/license');
+    expect(item.media.license.value, ' Sample license for a video');
 
-    expect(item.media.peerLink.type, "application/x-bittorrent");
-    expect(item.media.peerLink.href, "http://www.foo.org/sampleFile.torrent");
-    expect(item.media.peerLink.value, "");
+    expect(item.media.peerLink.type, 'application/x-bittorrent');
+    expect(item.media.peerLink.href, 'http://www.foo.org/sampleFile.torrent');
+    expect(item.media.peerLink.value, '');
 
-    expect(item.media.rights.status, "official");
+    expect(item.media.rights.status, 'official');
 
     expect(item.media.scenes.length, 2);
-    expect(item.media.scenes.first.title, "sceneTitle1");
-    expect(item.media.scenes.first.description, "sceneDesc1");
-    expect(item.media.scenes.first.startTime, "00:15");
-    expect(item.media.scenes.first.endTime, "00:45");
+    expect(item.media.scenes.first.title, 'sceneTitle1');
+    expect(item.media.scenes.first.description, 'sceneDesc1');
+    expect(item.media.scenes.first.startTime, '00:15');
+    expect(item.media.scenes.first.endTime, '00:45');
   });
 
-  test("parse Atom-Empty.xml", () {
-    var xmlString = File("test/xml/Atom-Empty.xml").readAsStringSync();
+  test('parse Atom-Empty.xml', () {
+    var xmlString = File('test/xml/Atom-Empty.xml').readAsStringSync();
 
     var feed = AtomFeed.parse(xmlString);
 
diff --git a/test/rss_test.dart b/test/rss_test.dart
index 16fc91e..8fa729f 100644
--- a/test/rss_test.dart
+++ b/test/rss_test.dart
@@ -7,54 +7,54 @@ import 'package:webfeed/domain/rss_itunes_type.dart';
 import 'package:webfeed/webfeed.dart';
 
 void main() {
-  test("parse Invalid.xml", () {
-    var xmlString = File("test/xml/Invalid.xml").readAsStringSync();
+  test('parse Invalid.xml', () {
+    var xmlString = File('test/xml/Invalid.xml').readAsStringSync();
 
     try {
       RssFeed.parse(xmlString);
-      fail("Should throw Argument Error");
+      fail('Should throw Argument Error');
     } on ArgumentError {}
   });
-  test("parse RSS.xml", () {
-    var xmlString = File("test/xml/RSS.xml").readAsStringSync();
+  test('parse RSS.xml', () {
+    var xmlString = File('test/xml/RSS.xml').readAsStringSync();
 
     var feed = RssFeed.parse(xmlString);
 
-    expect(feed.title, "News - Foo bar News");
+    expect(feed.title, 'News - Foo bar News');
     expect(feed.description,
-        "Foo bar News and Updates feed provided by Foo bar, Inc.");
-    expect(feed.link, "https://foo.bar.news/");
-    expect(feed.author, "hello@world.net");
-    expect(feed.language, "en-US");
-    expect(feed.lastBuildDate, "Mon, 26 Mar 2018 14:00:00 PDT");
-    expect(feed.generator, "Custom");
-    expect(feed.copyright, "Copyright 2018, Foo bar Inc.");
-    expect(feed.docs, "https://foo.bar.news/docs");
-    expect(feed.managingEditor, "alice@foo.bar.news");
-    expect(feed.rating, "The PICS rating of the feed");
-    expect(feed.webMaster, "webmaster@foo.bar.news");
+        'Foo bar News and Updates feed provided by Foo bar, Inc.');
+    expect(feed.link, 'https://foo.bar.news/');
+    expect(feed.author, 'hello@world.net');
+    expect(feed.language, 'en-US');
+    expect(feed.lastBuildDate, 'Mon, 26 Mar 2018 14:00:00 PDT');
+    expect(feed.generator, 'Custom');
+    expect(feed.copyright, 'Copyright 2018, Foo bar Inc.');
+    expect(feed.docs, 'https://foo.bar.news/docs');
+    expect(feed.managingEditor, 'alice@foo.bar.news');
+    expect(feed.rating, 'The PICS rating of the feed');
+    expect(feed.webMaster, 'webmaster@foo.bar.news');
     expect(feed.ttl, 60);
 
-    expect(feed.image.title, "Foo bar News");
-    expect(feed.image.url, "https://foo.bar.news/logo.gif");
-    expect(feed.image.link, "https://foo.bar.news/");
+    expect(feed.image.title, 'Foo bar News');
+    expect(feed.image.url, 'https://foo.bar.news/logo.gif');
+    expect(feed.image.link, 'https://foo.bar.news/');
 
-    expect(feed.cloud.domain, "radio.foo.bar.news");
-    expect(feed.cloud.port, "80");
-    expect(feed.cloud.path, "/RPC2");
-    expect(feed.cloud.registerProcedure, "foo.bar.rssPleaseNotify");
-    expect(feed.cloud.protocol, "xml-rpc");
+    expect(feed.cloud.domain, 'radio.foo.bar.news');
+    expect(feed.cloud.port, '80');
+    expect(feed.cloud.path, '/RPC2');
+    expect(feed.cloud.registerProcedure, 'foo.bar.rssPleaseNotify');
+    expect(feed.cloud.protocol, 'xml-rpc');
 
     expect(feed.categories.length, 2);
     expect(feed.categories[0].domain, null);
-    expect(feed.categories[0].value, "Ipsum");
-    expect(feed.categories[1].domain, "news");
-    expect(feed.categories[1].value, "Lorem Ipsum");
+    expect(feed.categories[0].value, 'Ipsum');
+    expect(feed.categories[1].domain, 'news');
+    expect(feed.categories[1].value, 'Lorem Ipsum');
 
     expect(feed.skipDays.length, 3);
-    expect(feed.skipDays.contains("Monday"), true);
-    expect(feed.skipDays.contains("Tuesday"), true);
-    expect(feed.skipDays.contains("Sunday"), true);
+    expect(feed.skipDays.contains('Monday'), true);
+    expect(feed.skipDays.contains('Tuesday'), true);
+    expect(feed.skipDays.contains('Sunday'), true);
 
     expect(feed.skipHours.length, 5);
     expect(feed.skipHours.contains(0), true);
@@ -66,58 +66,58 @@ void main() {
     expect(feed.items.length, 2);
 
     expect(feed.items.first.title,
-        "The standard Lorem Ipsum passage, used since the 1500s");
+        'The standard Lorem Ipsum passage, used since the 1500s');
     expect(feed.items.first.description,
-        "Lorem ipsum dolor sit amet, consectetur adipiscing elit");
-    expect(feed.items.first.link, "https://foo.bar.news/1");
-    expect(feed.items.first.guid, "https://foo.bar.news/1?guid");
+        'Lorem ipsum dolor sit amet, consectetur adipiscing elit');
+    expect(feed.items.first.link, 'https://foo.bar.news/1');
+    expect(feed.items.first.guid, 'https://foo.bar.news/1?guid');
     expect(feed.items.first.pubDate,
         DateTime(2018, 03, 26, 14)); //Mon, 26 Mar 2018 14:00:00 PDT
-    expect(feed.items.first.categories.first.domain, "news");
-    expect(feed.items.first.categories.first.value, "Lorem");
-    expect(feed.items.first.author, "alice@foo.bar.news");
-    expect(feed.items.first.source.url, "https://foo.bar.news/1?source");
-    expect(feed.items.first.source.value, "Foo Bar");
-    expect(feed.items.first.comments, "https://foo.bar.news/1/comments");
+    expect(feed.items.first.categories.first.domain, 'news');
+    expect(feed.items.first.categories.first.value, 'Lorem');
+    expect(feed.items.first.author, 'alice@foo.bar.news');
+    expect(feed.items.first.source.url, 'https://foo.bar.news/1?source');
+    expect(feed.items.first.source.value, 'Foo Bar');
+    expect(feed.items.first.comments, 'https://foo.bar.news/1/comments');
     expect(feed.items.first.enclosure.url,
-        "http://www.scripting.com/mp3s/weatherReportSuite.mp3");
+        'http://www.scripting.com/mp3s/weatherReportSuite.mp3');
     expect(feed.items.first.enclosure.length, 12216320);
-    expect(feed.items.first.enclosure.type, "audio/mpeg");
+    expect(feed.items.first.enclosure.type, 'audio/mpeg');
 
     expect(feed.items.first.content.value,
-        "<img width=\"1000\" height=\"690\" src=\"https://test.com/image_link\"/> Test content<br />");
+        '<img width="1000" height="690" src="https://test.com/image_link"/> Test content<br />');
     expect(
-        feed.items.first.content.images.first, "https://test.com/image_link");
+        feed.items.first.content.images.first, 'https://test.com/image_link');
   });
-  test("parse RSS-Media.xml", () {
-    var xmlString = File("test/xml/RSS-Media.xml").readAsStringSync();
+  test('parse RSS-Media.xml', () {
+    var xmlString = File('test/xml/RSS-Media.xml').readAsStringSync();
 
     var feed = RssFeed.parse(xmlString);
-    expect(feed.title, "Song Site");
+    expect(feed.title, 'Song Site');
     expect(
-        feed.description, "Media RSS example with new fields added in v1.5.0");
+        feed.description, 'Media RSS example with new fields added in v1.5.0');
 
     expect(feed.items.length, 1);
 
     var item = feed.items.first;
     expect(item.title, null);
-    expect(item.link, "http://www.foo.com");
+    expect(item.link, 'http://www.foo.com');
     expect(item.pubDate,
         DateTime(2001, 08, 27, 16, 08, 56)); //Mon, 27 Aug 2001 16:08:56 PST
 
     expect(item.media.group.contents.length, 5);
     expect(item.media.group.credits.length, 2);
-    expect(item.media.group.category.value, "music/artist name/album/song");
-    expect(item.media.group.rating.value, "nonadult");
+    expect(item.media.group.category.value, 'music/artist name/album/song');
+    expect(item.media.group.rating.value, 'nonadult');
 
     expect(item.media.contents.length, 2);
     var mediaContent = item.media.contents.first;
-    expect(mediaContent.url, "http://www.foo.com/video.mov");
-    expect(mediaContent.type, "video/quicktime");
+    expect(mediaContent.url, 'http://www.foo.com/video.mov');
+    expect(mediaContent.type, 'video/quicktime');
     expect(mediaContent.fileSize, 2000);
-    expect(mediaContent.medium, "video");
+    expect(mediaContent.medium, 'video');
     expect(mediaContent.isDefault, true);
-    expect(mediaContent.expression, "full");
+    expect(mediaContent.expression, 'full');
     expect(mediaContent.bitrate, 128);
     expect(mediaContent.framerate, 25);
     expect(mediaContent.samplingrate, 44.1);
@@ -125,54 +125,54 @@ void main() {
 
     expect(item.media.credits.length, 2);
     var mediaCredit = item.media.credits.first;
-    expect(mediaCredit.role, "owner1");
-    expect(mediaCredit.scheme, "urn:yvs");
-    expect(mediaCredit.value, "copyright holder of the entity");
+    expect(mediaCredit.role, 'owner1');
+    expect(mediaCredit.scheme, 'urn:yvs');
+    expect(mediaCredit.value, 'copyright holder of the entity');
 
     expect(item.media.category.scheme,
-        "http://search.yahoo.com/mrss/category_ schema");
-    expect(item.media.category.label, "Music");
-    expect(item.media.category.value, "music/artist/album/song");
+        'http://search.yahoo.com/mrss/category_ schema');
+    expect(item.media.category.label, 'Music');
+    expect(item.media.category.value, 'music/artist/album/song');
 
-    expect(item.media.rating.scheme, "urn:simple");
-    expect(item.media.rating.value, "adult");
+    expect(item.media.rating.scheme, 'urn:simple');
+    expect(item.media.rating.value, 'adult');
 
-    expect(item.media.title.type, "plain");
+    expect(item.media.title.type, 'plain');
     expect(item.media.title.value, "The Judy's -- The Moo Song");
 
-    expect(item.media.description.type, "plain");
+    expect(item.media.description.type, 'plain');
     expect(item.media.description.value,
-        "This was some really bizarre band I listened to as a young lad.");
+        'This was some really bizarre band I listened to as a young lad.');
 
-    expect(item.media.keywords, "kitty, cat, big dog, yarn, fluffy");
+    expect(item.media.keywords, 'kitty, cat, big dog, yarn, fluffy');
 
     expect(item.media.thumbnails.length, 2);
     var mediaThumbnail = item.media.thumbnails.first;
-    expect(mediaThumbnail.url, "http://www.foo.com/keyframe1.jpg");
-    expect(mediaThumbnail.width, "75");
-    expect(mediaThumbnail.height, "50");
-    expect(mediaThumbnail.time, "12:05:01.123");
+    expect(mediaThumbnail.url, 'http://www.foo.com/keyframe1.jpg');
+    expect(mediaThumbnail.width, '75');
+    expect(mediaThumbnail.height, '50');
+    expect(mediaThumbnail.time, '12:05:01.123');
 
-    expect(item.media.hash.algo, "md5");
-    expect(item.media.hash.value, "dfdec888b72151965a34b4b59031290a");
+    expect(item.media.hash.algo, 'md5');
+    expect(item.media.hash.value, 'dfdec888b72151965a34b4b59031290a');
 
-    expect(item.media.player.url, "http://www.foo.com/player?id=1111");
+    expect(item.media.player.url, 'http://www.foo.com/player?id=1111');
     expect(item.media.player.width, 400);
     expect(item.media.player.height, 200);
-    expect(item.media.player.value, "");
+    expect(item.media.player.value, '');
 
-    expect(item.media.copyright.url, "http://blah.com/additional-info.html");
-    expect(item.media.copyright.value, "2005 FooBar Media");
+    expect(item.media.copyright.url, 'http://blah.com/additional-info.html');
+    expect(item.media.copyright.value, '2005 FooBar Media');
 
-    expect(item.media.text.type, "plain");
-    expect(item.media.text.lang, "en");
-    expect(item.media.text.start, "00:00:03.000");
-    expect(item.media.text.end, "00:00:10.000");
-    expect(item.media.text.value, " Oh, say, can you see");
+    expect(item.media.text.type, 'plain');
+    expect(item.media.text.lang, 'en');
+    expect(item.media.text.start, '00:00:03.000');
+    expect(item.media.text.end, '00:00:10.000');
+    expect(item.media.text.value, ' Oh, say, can you see');
 
-    expect(item.media.restriction.relationship, "allow");
-    expect(item.media.restriction.type, "country");
-    expect(item.media.restriction.value, "au us");
+    expect(item.media.restriction.relationship, 'allow');
+    expect(item.media.restriction.type, 'country');
+    expect(item.media.restriction.value, 'au us');
 
     expect(item.media.community.starRating.average, 3.5);
     expect(item.media.community.starRating.count, 20);
@@ -180,97 +180,97 @@ void main() {
     expect(item.media.community.starRating.max, 10);
     expect(item.media.community.statistics.views, 5);
     expect(item.media.community.statistics.favorites, 4);
-    expect(item.media.community.tags.tags, "news: 5, abc:3");
+    expect(item.media.community.tags.tags, 'news: 5, abc:3');
     expect(item.media.community.tags.weight, 1);
 
     expect(item.media.comments.length, 2);
-    expect(item.media.comments.first, "comment1");
-    expect(item.media.comments.last, "comment2");
+    expect(item.media.comments.first, 'comment1');
+    expect(item.media.comments.last, 'comment2');
 
-    expect(item.media.embed.url, "http://www.foo.com/player.swf");
+    expect(item.media.embed.url, 'http://www.foo.com/player.swf');
     expect(item.media.embed.width, 512);
     expect(item.media.embed.height, 323);
     expect(item.media.embed.params.length, 5);
-    expect(item.media.embed.params.first.name, "type");
+    expect(item.media.embed.params.first.name, 'type');
     expect(
-        item.media.embed.params.first.value, "application/x-shockwave-flash");
+        item.media.embed.params.first.value, 'application/x-shockwave-flash');
 
     expect(item.media.responses.length, 2);
-    expect(item.media.responses.first, "http://www.response1.com");
-    expect(item.media.responses.last, "http://www.response2.com");
+    expect(item.media.responses.first, 'http://www.response1.com');
+    expect(item.media.responses.last, 'http://www.response2.com');
 
     expect(item.media.backLinks.length, 2);
-    expect(item.media.backLinks.first, "http://www.backlink1.com");
-    expect(item.media.backLinks.last, "http://www.backlink2.com");
+    expect(item.media.backLinks.first, 'http://www.backlink1.com');
+    expect(item.media.backLinks.last, 'http://www.backlink2.com');
 
-    expect(item.media.status.state, "active");
+    expect(item.media.status.state, 'active');
     expect(item.media.status.reason, null);
 
     expect(item.media.prices.length, 2);
     expect(item.media.prices.first.price, 19.99);
-    expect(item.media.prices.first.type, "rent");
+    expect(item.media.prices.first.type, 'rent');
     expect(
-        item.media.prices.first.info, "http://www.dummy.jp/package_info.html");
-    expect(item.media.prices.first.currency, "EUR");
+        item.media.prices.first.info, 'http://www.dummy.jp/package_info.html');
+    expect(item.media.prices.first.currency, 'EUR');
 
-    expect(item.media.license.type, "text/html");
-    expect(item.media.license.href, "http://www.licensehost.com/license");
-    expect(item.media.license.value, " Sample license for a video");
+    expect(item.media.license.type, 'text/html');
+    expect(item.media.license.href, 'http://www.licensehost.com/license');
+    expect(item.media.license.value, ' Sample license for a video');
 
-    expect(item.media.peerLink.type, "application/x-bittorrent");
-    expect(item.media.peerLink.href, "http://www.foo.org/sampleFile.torrent");
-    expect(item.media.peerLink.value, "");
+    expect(item.media.peerLink.type, 'application/x-bittorrent');
+    expect(item.media.peerLink.href, 'http://www.foo.org/sampleFile.torrent');
+    expect(item.media.peerLink.value, '');
 
-    expect(item.media.rights.status, "official");
+    expect(item.media.rights.status, 'official');
 
     expect(item.media.scenes.length, 2);
-    expect(item.media.scenes.first.title, "sceneTitle1");
-    expect(item.media.scenes.first.description, "sceneDesc1");
-    expect(item.media.scenes.first.startTime, "00:15");
-    expect(item.media.scenes.first.endTime, "00:45");
+    expect(item.media.scenes.first.title, 'sceneTitle1');
+    expect(item.media.scenes.first.description, 'sceneDesc1');
+    expect(item.media.scenes.first.startTime, '00:15');
+    expect(item.media.scenes.first.endTime, '00:45');
   });
-  test("parse RSS-DC.xml", () {
-    var xmlString = File("test/xml/RSS-DC.xml").readAsStringSync();
+  test('parse RSS-DC.xml', () {
+    var xmlString = File('test/xml/RSS-DC.xml').readAsStringSync();
 
     var feed = RssFeed.parse(xmlString);
 
-    expect(feed.dc.title, "title");
-    expect(feed.dc.creator, "creator");
-    expect(feed.dc.subject, "subject");
-    expect(feed.dc.description, "description");
-    expect(feed.dc.publisher, "publisher");
-    expect(feed.dc.contributor, "contributor");
+    expect(feed.dc.title, 'title');
+    expect(feed.dc.creator, 'creator');
+    expect(feed.dc.subject, 'subject');
+    expect(feed.dc.description, 'description');
+    expect(feed.dc.publisher, 'publisher');
+    expect(feed.dc.contributor, 'contributor');
     expect(feed.dc.date, DateTime.utc(2000, 1, 1, 12));
     expect(feed.dc.created, DateTime.utc(2000, 1, 1, 13));
     expect(feed.dc.modified, DateTime.utc(2000, 1, 1, 14));
-    expect(feed.dc.type, "type");
-    expect(feed.dc.format, "format");
-    expect(feed.dc.identifier, "identifier");
-    expect(feed.dc.source, "source");
-    expect(feed.dc.language, "language");
-    expect(feed.dc.relation, "relation");
-    expect(feed.dc.coverage, "coverage");
-    expect(feed.dc.rights, "rights");
-
-    expect(feed.items.first.dc.title, "title");
-    expect(feed.items.first.dc.creator, "creator");
-    expect(feed.items.first.dc.subject, "subject");
-    expect(feed.items.first.dc.description, "description");
-    expect(feed.items.first.dc.publisher, "publisher");
-    expect(feed.items.first.dc.contributor, "contributor");
+    expect(feed.dc.type, 'type');
+    expect(feed.dc.format, 'format');
+    expect(feed.dc.identifier, 'identifier');
+    expect(feed.dc.source, 'source');
+    expect(feed.dc.language, 'language');
+    expect(feed.dc.relation, 'relation');
+    expect(feed.dc.coverage, 'coverage');
+    expect(feed.dc.rights, 'rights');
+
+    expect(feed.items.first.dc.title, 'title');
+    expect(feed.items.first.dc.creator, 'creator');
+    expect(feed.items.first.dc.subject, 'subject');
+    expect(feed.items.first.dc.description, 'description');
+    expect(feed.items.first.dc.publisher, 'publisher');
+    expect(feed.items.first.dc.contributor, 'contributor');
     expect(feed.items.first.dc.date, DateTime.utc(2000, 1, 1, 12));
-    expect(feed.items.first.dc.type, "type");
-    expect(feed.items.first.dc.format, "format");
-    expect(feed.items.first.dc.identifier, "identifier");
-    expect(feed.items.first.dc.source, "source");
-    expect(feed.items.first.dc.language, "language");
-    expect(feed.items.first.dc.relation, "relation");
-    expect(feed.items.first.dc.coverage, "coverage");
-    expect(feed.items.first.dc.rights, "rights");
+    expect(feed.items.first.dc.type, 'type');
+    expect(feed.items.first.dc.format, 'format');
+    expect(feed.items.first.dc.identifier, 'identifier');
+    expect(feed.items.first.dc.source, 'source');
+    expect(feed.items.first.dc.language, 'language');
+    expect(feed.items.first.dc.relation, 'relation');
+    expect(feed.items.first.dc.coverage, 'coverage');
+    expect(feed.items.first.dc.rights, 'rights');
   });
 
-  test("parse RSS-Empty.xml", () {
-    var xmlString = File("test/xml/RSS-Empty.xml").readAsStringSync();
+  test('parse RSS-Empty.xml', () {
+    var xmlString = File('test/xml/RSS-Empty.xml').readAsStringSync();
 
     var feed = RssFeed.parse(xmlString);
 
@@ -313,39 +313,39 @@ void main() {
     expect(feed.items.first.content, null);
   });
 
-  test("parse RSS-Itunes.xml", () {
-    var xmlString = File("test/xml/RSS-Itunes.xml").readAsStringSync();
+  test('parse RSS-Itunes.xml', () {
+    var xmlString = File('test/xml/RSS-Itunes.xml').readAsStringSync();
 
     var feed = RssFeed.parse(xmlString);
 
-    expect(feed.itunes.author, "Changelog Media");
-    expect(feed.itunes.summary, "Foo");
+    expect(feed.itunes.author, 'Changelog Media');
+    expect(feed.itunes.summary, 'Foo');
     expect(feed.itunes.explicit, false);
     expect(feed.itunes.image.href,
-        "https://cdn.changelog.com/uploads/covers/go-time-original.png?v=63725770357");
+        'https://cdn.changelog.com/uploads/covers/go-time-original.png?v=63725770357');
     expect(feed.itunes.keywords,
-        "go,golang,open source,software,development".split(","));
-    expect(feed.itunes.owner.name, "Changelog Media");
-    expect(feed.itunes.owner.email, "editors@changelog.com");
+        'go,golang,open source,software,development'.split(','));
+    expect(feed.itunes.owner.name, 'Changelog Media');
+    expect(feed.itunes.owner.email, 'editors@changelog.com');
     expect(
         Set.from([
           feed.itunes.categories[0].category,
           feed.itunes.categories[1].category
         ]),
-        ["Technology", "Foo"]);
+        ['Technology', 'Foo']);
     for (var category in feed.itunes.categories) {
       switch (category.category) {
-        case "Foo":
-          expect(category.subCategories, ["Bar", "Baz"]);
+        case 'Foo':
+          expect(category.subCategories, ['Bar', 'Baz']);
           break;
-        case "Technology":
-          expect(category.subCategories, ["Software How-To", "Tech News"]);
+        case 'Technology':
+          expect(category.subCategories, ['Software How-To', 'Tech News']);
           break;
       }
     }
-    expect(feed.itunes.title, "Go Time");
+    expect(feed.itunes.title, 'Go Time');
     expect(feed.itunes.type, RssItunesType.serial);
-    expect(feed.itunes.newFeedUrl, "wubawuba");
+    expect(feed.itunes.newFeedUrl, 'wubawuba');
     expect(feed.itunes.block, true);
     expect(feed.itunes.complete, true);
 
@@ -354,17 +354,17 @@ void main() {
     expect(item.itunes.episode, 1);
     expect(item.itunes.season, 1);
     expect(item.itunes.image.href,
-        "https://cdn.changelog.com/uploads/covers/go-time-original.png?v=63725770357");
+        'https://cdn.changelog.com/uploads/covers/go-time-original.png?v=63725770357');
     expect(item.itunes.duration, Duration(minutes: 32, seconds: 30));
     expect(item.itunes.explicit, false);
     expect(item.itunes.keywords,
-        "go,golang,open source,software,development".split(","));
-    expect(item.itunes.subtitle, "with Erik, Carlisia, and Brian");
-    expect(item.itunes.summary, "Foo");
+        'go,golang,open source,software,development'.split(','));
+    expect(item.itunes.subtitle, 'with Erik, Carlisia, and Brian');
+    expect(item.itunes.summary, 'Foo');
     expect(item.itunes.author,
-        "Erik St. Martin, Carlisia Pinto, and Brian Ketelsen");
+        'Erik St. Martin, Carlisia Pinto, and Brian Ketelsen');
     expect(item.itunes.explicit, false);
-    expect(item.itunes.title, "awesome title");
+    expect(item.itunes.title, 'awesome title');
     expect(item.itunes.block, false);
   });
 }