Fix iTunes extension writing

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## 2.x.x - Unreleased
 
+- Fix iTunes extension writing [`#151`](https://github.com/rust-syndication/rss/pull/151)
+
 ## 2.0.3 - 2023-03-27
 
 - Upgrade `quick_xml` to `0.28` [`#146`](https://github.com/rust-syndication/rss/pull/146)

src/extension/itunes/itunes_channel_extension.rs

@@ -12,7 +12,7 @@ use quick_xml::events::{BytesStart, Event};
 use quick_xml::Error as XmlError;
 use quick_xml::Writer;
 
-use super::{parse_categories, parse_image, parse_owner};
+use super::{parse_categories, parse_image, parse_owner, NAMESPACE};
 use crate::extension::itunes::{ITunesCategory, ITunesOwner};
 use crate::extension::util::remove_extension_value;
 use crate::extension::Extension;
@@ -553,6 +553,12 @@ impl ToXml for ITunesChannelExtension {
 
         Ok(())
     }
+
+    fn used_namespaces(&self) -> BTreeMap<String, String> {
+        let mut namespaces = BTreeMap::new();
+        namespaces.insert("itunes".to_owned(), NAMESPACE.to_owned());
+        namespaces
+    }
 }
 
 #[cfg(feature = "builders")]

tests/write.rs

@@ -1,8 +1,9 @@
 extern crate rss;
 
 use rss::{
-    extension, CategoryBuilder, Channel, ChannelBuilder, CloudBuilder, EnclosureBuilder,
-    GuidBuilder, ImageBuilder, Item, ItemBuilder, SourceBuilder, TextInputBuilder,
+    extension, extension::itunes::ITunesChannelExtensionBuilder, CategoryBuilder, Channel,
+    ChannelBuilder, CloudBuilder, EnclosureBuilder, GuidBuilder, ImageBuilder, Item, ItemBuilder,
+    SourceBuilder, TextInputBuilder,
 };
 use std::collections::BTreeMap;
 
@@ -105,6 +106,33 @@ fn write_itunes() {
     test_write!(channel);
 }
 
+#[test]
+fn write_itunes_namespace() {
+    let itunes_extention = ITunesChannelExtensionBuilder::default()
+        .author(Some("author".to_string()))
+        .build();
+    let channel = rss::ChannelBuilder::default()
+        .title("Channel Title")
+        .link("http://example.com")
+        .description("Channel Description")
+        .itunes_ext(itunes_extention)
+        .build();
+
+    let xml = String::from_utf8(channel.pretty_write_to(Vec::new(), b' ', 4).unwrap()).unwrap();
+    assert_eq!(
+        xml,
+        r##"<?xml version="1.0" encoding="utf-8"?>
+<rss version="2.0" xmlns:itunes="http://www.itunes.com/dtds/podcast-1.0.dtd">
+    <channel>
+        <title>Channel Title</title>
+        <link>http://example.com</link>
+        <description>Channel Description</description>
+        <itunes:author>author</itunes:author>
+    </channel>
+</rss>"##
+    );
+}
+
 #[test]
 fn write_dublincore() {
     let input = include_str!("data/dublincore.xml");