fix(blog): apply trailing slash to blog feed (#9920)

Co-authored-by: sebastien <lorber.sebastien@gmail.com>

packages/docusaurus-plugin-content-blog/src/__tests__/__snapshots__/feed.test.ts.snap

@@ -220,6 +220,134 @@ exports[`atom has feed item for each post 1`] = `
 ]
 `;
 
+exports[`atom has feed item for each post - with trailing slash 1`] = `
+[
+  "<?xml version="1.0" encoding="utf-8"?>
+<feed xmlns="http://www.w3.org/2005/Atom">
+    <id>https://docusaurus.io/myBaseUrl/blog/</id>
+    <title>Hello Blog</title>
+    <updated>2023-07-23T00:00:00.000Z</updated>
+    <generator>https://github.com/jpmonette/feed</generator>
+    <link rel="alternate" href="https://docusaurus.io/myBaseUrl/blog/"/>
+    <subtitle>Hello Blog</subtitle>
+    <icon>https://docusaurus.io/myBaseUrl/image/favicon.ico</icon>
+    <rights>Copyright</rights>
+    <entry>
+        <title type="html"><![CDATA[test links]]></title>
+        <id>https://docusaurus.io/myBaseUrl/blog/blog-with-links/</id>
+        <link href="https://docusaurus.io/myBaseUrl/blog/blog-with-links/"/>
+        <updated>2023-07-23T00:00:00.000Z</updated>
+        <summary type="html"><![CDATA[absolute full url]]></summary>
+        <content type="html"><![CDATA[<p><a href="https://github.com/facebook/docusaurus" target="_blank" rel="noopener noreferrer">absolute full url</a></p>
+<p><a href="https://docusaurus.io/blog/heading-as-title">absolute pathname</a></p>
+<p><a href="https://docusaurus.io/blog/heading-as-title">relative pathname</a></p>
+<p><a href="https://docusaurus.io/blog/heading-as-title">md link</a></p>
+<p><a href="https://docusaurus.io/myBaseUrl/blog/blog-with-links/#title">anchor</a></p>
+<p><a href="https://docusaurus.io/blog/heading-as-title#title">relative pathname + anchor</a></p>
+<p><img loading="lazy" src="https://docusaurus.io/assets/images/test-image-742d39e51f41482e8132e79c09ad4eea.png" width="760" height="160" class="img_yGFe"></p>
+<p><img loading="lazy" src="https://docusaurus.io/assets/images/slash-introducing-411a16dd05086935b8e9ddae38ae9b45.svg" alt="" class="img_yGFe"></p>
+<img srcset="https://docusaurus.io/img/test-image.png 300w, https://docusaurus.io/img/docusaurus-social-card.png 500w">
+<img src="https://docusaurus.io/img/test-image.png">]]></content>
+    </entry>
+    <entry>
+        <title type="html"><![CDATA[MDX Blog Sample with require calls]]></title>
+        <id>https://docusaurus.io/myBaseUrl/blog/mdx-require-blog-post/</id>
+        <link href="https://docusaurus.io/myBaseUrl/blog/mdx-require-blog-post/"/>
+        <updated>2021-03-06T00:00:00.000Z</updated>
+        <summary type="html"><![CDATA[Test MDX with require calls]]></summary>
+        <content type="html"><![CDATA[<p>Test MDX with require calls</p>
+<!-- -->
+<!-- -->
+<img src="https://docusaurus.io/img/test-image.png">
+<img src="https://docusaurus.io/assets/images/test-image-742d39e51f41482e8132e79c09ad4eea.png">
+<img src="https://docusaurus.io/assets/images/test-image-742d39e51f41482e8132e79c09ad4eea.png">]]></content>
+    </entry>
+    <entry>
+        <title type="html"><![CDATA[Full Blog Sample]]></title>
+        <id>https://docusaurus.io/myBaseUrl/blog/mdx-blog-post/</id>
+        <link href="https://docusaurus.io/myBaseUrl/blog/mdx-blog-post/"/>
+        <updated>2021-03-05T00:00:00.000Z</updated>
+        <summary type="html"><![CDATA[HTML Heading 1]]></summary>
+        <content type="html"><![CDATA[<h1>HTML Heading 1</h1>
+<h2>HTML Heading 2</h2>
+<p>HTML Paragraph</p>
+<!-- -->
+<!-- -->
+<p>Import DOM</p>
+<h1>Heading 1</h1>
+<h2 class="anchor anchorWithHideOnScrollNavbar_G5V2" id="heading-2">Heading 2<a href="https://docusaurus.io/myBaseUrl/blog/mdx-blog-post/#heading-2" class="hash-link" aria-label="Direct link to Heading 2" title="Direct link to Heading 2">​</a></h2>
+<h3 class="anchor anchorWithHideOnScrollNavbar_G5V2" id="heading-3">Heading 3<a href="https://docusaurus.io/myBaseUrl/blog/mdx-blog-post/#heading-3" class="hash-link" aria-label="Direct link to Heading 3" title="Direct link to Heading 3">​</a></h3>
+<h4 class="anchor anchorWithHideOnScrollNavbar_G5V2" id="heading-4">Heading 4<a href="https://docusaurus.io/myBaseUrl/blog/mdx-blog-post/#heading-4" class="hash-link" aria-label="Direct link to Heading 4" title="Direct link to Heading 4">​</a></h4>
+<h5 class="anchor anchorWithHideOnScrollNavbar_G5V2" id="heading-5">Heading 5<a href="https://docusaurus.io/myBaseUrl/blog/mdx-blog-post/#heading-5" class="hash-link" aria-label="Direct link to Heading 5" title="Direct link to Heading 5">​</a></h5>
+<ul>
+<li>list1</li>
+<li>list2</li>
+<li>list3</li>
+</ul>
+<ul>
+<li>list1</li>
+<li>list2</li>
+<li>list3</li>
+</ul>
+<p>Normal Text <em>Italics Text</em> <strong>Bold Text</strong></p>
+<p><a href="https://v2.docusaurus.io/" target="_blank" rel="noopener noreferrer">link</a> <img loading="lazy" src="https://v2.docusaurus.io/" alt="image" class="img_yGFe"></p>]]></content>
+    </entry>
+    <entry>
+        <title type="html"><![CDATA[Complex Slug]]></title>
+        <id>https://docusaurus.io/myBaseUrl/blog/hey/my super path/héllô/</id>
+        <link href="https://docusaurus.io/myBaseUrl/blog/hey/my super path/héllô/"/>
+        <updated>2020-08-16T00:00:00.000Z</updated>
+        <summary type="html"><![CDATA[complex url slug]]></summary>
+        <content type="html"><![CDATA[<p>complex url slug</p>]]></content>
+        <category label="date" term="date"/>
+        <category label="complex" term="complex"/>
+    </entry>
+    <entry>
+        <title type="html"><![CDATA[Simple Slug]]></title>
+        <id>https://docusaurus.io/myBaseUrl/blog/simple/slug/</id>
+        <link href="https://docusaurus.io/myBaseUrl/blog/simple/slug/"/>
+        <updated>2020-08-15T00:00:00.000Z</updated>
+        <summary type="html"><![CDATA[simple url slug]]></summary>
+        <content type="html"><![CDATA[<p>simple url slug</p>]]></content>
+        <author>
+            <name>Sébastien Lorber</name>
+            <uri>https://sebastienlorber.com</uri>
+        </author>
+    </entry>
+    <entry>
+        <title type="html"><![CDATA[some heading]]></title>
+        <id>https://docusaurus.io/myBaseUrl/blog/heading-as-title/</id>
+        <link href="https://docusaurus.io/myBaseUrl/blog/heading-as-title/"/>
+        <updated>2019-01-02T00:00:00.000Z</updated>
+    </entry>
+    <entry>
+        <title type="html"><![CDATA[date-matter]]></title>
+        <id>https://docusaurus.io/myBaseUrl/blog/date-matter/</id>
+        <link href="https://docusaurus.io/myBaseUrl/blog/date-matter/"/>
+        <updated>2019-01-01T00:00:00.000Z</updated>
+        <summary type="html"><![CDATA[date inside front matter]]></summary>
+        <content type="html"><![CDATA[<p>date inside front matter</p>]]></content>
+        <category label="date" term="date"/>
+    </entry>
+    <entry>
+        <title type="html"><![CDATA[Happy 1st Birthday Slash! (translated)]]></title>
+        <id>https://docusaurus.io/myBaseUrl/blog/2018/12/14/Happy-First-Birthday-Slash/</id>
+        <link href="https://docusaurus.io/myBaseUrl/blog/2018/12/14/Happy-First-Birthday-Slash/"/>
+        <updated>2018-12-14T00:00:00.000Z</updated>
+        <summary type="html"><![CDATA[Happy birthday! (translated)]]></summary>
+        <content type="html"><![CDATA[<p>Happy birthday! (translated)</p>]]></content>
+        <author>
+            <name>Yangshun Tay (translated)</name>
+        </author>
+        <author>
+            <name>Sébastien Lorber (translated)</name>
+            <email>lorber.sebastien@gmail.com</email>
+        </author>
+    </entry>
+</feed>",
+]
+`;
+
 exports[`json filters to the first two entries 1`] = `
 [
   "{
@@ -378,6 +506,102 @@ exports[`json has feed item for each post 1`] = `
 ]
 `;
 
+exports[`json has feed item for each post - with trailing slash 1`] = `
+[
+  "{
+    "version": "https://jsonfeed.org/version/1",
+    "title": "Hello Blog",
+    "home_page_url": "https://docusaurus.io/myBaseUrl/blog/",
+    "description": "Hello Blog",
+    "items": [
+        {
+            "id": "https://docusaurus.io/myBaseUrl/blog/blog-with-links/",
+            "content_html": "<p><a href=\\"https://github.com/facebook/docusaurus\\" target=\\"_blank\\" rel=\\"noopener noreferrer\\">absolute full url</a></p>/n<p><a href=\\"https://docusaurus.io/blog/heading-as-title\\">absolute pathname</a></p>/n<p><a href=\\"https://docusaurus.io/blog/heading-as-title\\">relative pathname</a></p>/n<p><a href=\\"https://docusaurus.io/blog/heading-as-title\\">md link</a></p>/n<p><a href=\\"https://docusaurus.io/myBaseUrl/blog/blog-with-links/#title\\">anchor</a></p>/n<p><a href=\\"https://docusaurus.io/blog/heading-as-title#title\\">relative pathname + anchor</a></p>/n<p><img loading=\\"lazy\\" src=\\"https://docusaurus.io/assets/images/test-image-742d39e51f41482e8132e79c09ad4eea.png\\" width=\\"760\\" height=\\"160\\" class=\\"img_yGFe\\"></p>/n<p><img loading=\\"lazy\\" src=\\"https://docusaurus.io/assets/images/slash-introducing-411a16dd05086935b8e9ddae38ae9b45.svg\\" alt=\\"\\" class=\\"img_yGFe\\"></p>/n<img srcset=\\"https://docusaurus.io/img/test-image.png 300w, https://docusaurus.io/img/docusaurus-social-card.png 500w\\">/n<img src=\\"https://docusaurus.io/img/test-image.png\\">",
+            "url": "https://docusaurus.io/myBaseUrl/blog/blog-with-links/",
+            "title": "test links",
+            "summary": "absolute full url",
+            "date_modified": "2023-07-23T00:00:00.000Z",
+            "tags": []
+        },
+        {
+            "id": "https://docusaurus.io/myBaseUrl/blog/mdx-require-blog-post/",
+            "content_html": "<p>Test MDX with require calls</p>/n<!-- -->/n<!-- -->/n<img src=\\"https://docusaurus.io/img/test-image.png\\">/n<img src=\\"https://docusaurus.io/assets/images/test-image-742d39e51f41482e8132e79c09ad4eea.png\\">/n<img src=\\"https://docusaurus.io/assets/images/test-image-742d39e51f41482e8132e79c09ad4eea.png\\">",
+            "url": "https://docusaurus.io/myBaseUrl/blog/mdx-require-blog-post/",
+            "title": "MDX Blog Sample with require calls",
+            "summary": "Test MDX with require calls",
+            "date_modified": "2021-03-06T00:00:00.000Z",
+            "tags": []
+        },
+        {
+            "id": "https://docusaurus.io/myBaseUrl/blog/mdx-blog-post/",
+            "content_html": "<h1>HTML Heading 1</h1>/n<h2>HTML Heading 2</h2>/n<p>HTML Paragraph</p>/n<!-- -->/n<!-- -->/n<p>Import DOM</p>/n<h1>Heading 1</h1>/n<h2 class=\\"anchor anchorWithHideOnScrollNavbar_G5V2\\" id=\\"heading-2\\">Heading 2<a href=\\"https://docusaurus.io/myBaseUrl/blog/mdx-blog-post/#heading-2\\" class=\\"hash-link\\" aria-label=\\"Direct link to Heading 2\\" title=\\"Direct link to Heading 2\\">​</a></h2>/n<h3 class=\\"anchor anchorWithHideOnScrollNavbar_G5V2\\" id=\\"heading-3\\">Heading 3<a href=\\"https://docusaurus.io/myBaseUrl/blog/mdx-blog-post/#heading-3\\" class=\\"hash-link\\" aria-label=\\"Direct link to Heading 3\\" title=\\"Direct link to Heading 3\\">​</a></h3>/n<h4 class=\\"anchor anchorWithHideOnScrollNavbar_G5V2\\" id=\\"heading-4\\">Heading 4<a href=\\"https://docusaurus.io/myBaseUrl/blog/mdx-blog-post/#heading-4\\" class=\\"hash-link\\" aria-label=\\"Direct link to Heading 4\\" title=\\"Direct link to Heading 4\\">​</a></h4>/n<h5 class=\\"anchor anchorWithHideOnScrollNavbar_G5V2\\" id=\\"heading-5\\">Heading 5<a href=\\"https://docusaurus.io/myBaseUrl/blog/mdx-blog-post/#heading-5\\" class=\\"hash-link\\" aria-label=\\"Direct link to Heading 5\\" title=\\"Direct link to Heading 5\\">​</a></h5>/n<ul>/n<li>list1</li>/n<li>list2</li>/n<li>list3</li>/n</ul>/n<ul>/n<li>list1</li>/n<li>list2</li>/n<li>list3</li>/n</ul>/n<p>Normal Text <em>Italics Text</em> <strong>Bold Text</strong></p>/n<p><a href=\\"https://v2.docusaurus.io/\\" target=\\"_blank\\" rel=\\"noopener noreferrer\\">link</a> <img loading=\\"lazy\\" src=\\"https://v2.docusaurus.io/\\" alt=\\"image\\" class=\\"img_yGFe\\"></p>",
+            "url": "https://docusaurus.io/myBaseUrl/blog/mdx-blog-post/",
+            "title": "Full Blog Sample",
+            "summary": "HTML Heading 1",
+            "date_modified": "2021-03-05T00:00:00.000Z",
+            "tags": []
+        },
+        {
+            "id": "https://docusaurus.io/myBaseUrl/blog/hey/my super path/héllô/",
+            "content_html": "<p>complex url slug</p>",
+            "url": "https://docusaurus.io/myBaseUrl/blog/hey/my super path/héllô/",
+            "title": "Complex Slug",
+            "summary": "complex url slug",
+            "date_modified": "2020-08-16T00:00:00.000Z",
+            "tags": [
+                "date",
+                "complex"
+            ]
+        },
+        {
+            "id": "https://docusaurus.io/myBaseUrl/blog/simple/slug/",
+            "content_html": "<p>simple url slug</p>",
+            "url": "https://docusaurus.io/myBaseUrl/blog/simple/slug/",
+            "title": "Simple Slug",
+            "summary": "simple url slug",
+            "date_modified": "2020-08-15T00:00:00.000Z",
+            "author": {
+                "name": "Sébastien Lorber",
+                "url": "https://sebastienlorber.com"
+            },
+            "tags": []
+        },
+        {
+            "id": "https://docusaurus.io/myBaseUrl/blog/heading-as-title/",
+            "content_html": "",
+            "url": "https://docusaurus.io/myBaseUrl/blog/heading-as-title/",
+            "title": "some heading",
+            "date_modified": "2019-01-02T00:00:00.000Z",
+            "tags": []
+        },
+        {
+            "id": "https://docusaurus.io/myBaseUrl/blog/date-matter/",
+            "content_html": "<p>date inside front matter</p>",
+            "url": "https://docusaurus.io/myBaseUrl/blog/date-matter/",
+            "title": "date-matter",
+            "summary": "date inside front matter",
+            "date_modified": "2019-01-01T00:00:00.000Z",
+            "tags": [
+                "date"
+            ]
+        },
+        {
+            "id": "https://docusaurus.io/myBaseUrl/blog/2018/12/14/Happy-First-Birthday-Slash/",
+            "content_html": "<p>Happy birthday! (translated)</p>",
+            "url": "https://docusaurus.io/myBaseUrl/blog/2018/12/14/Happy-First-Birthday-Slash/",
+            "title": "Happy 1st Birthday Slash! (translated)",
+            "summary": "Happy birthday! (translated)",
+            "date_modified": "2018-12-14T00:00:00.000Z",
+            "author": {
+                "name": "Yangshun Tay (translated)"
+            },
+            "tags": []
+        }
+    ]
+}",
+]
+`;
+
 exports[`rss filters to the first two entries 1`] = `
 [
   "<?xml version="1.0" encoding="utf-8"?>
@@ -593,3 +817,123 @@ exports[`rss has feed item for each post 1`] = `
 </rss>",
 ]
 `;
+
+exports[`rss has feed item for each post - with trailing slash 1`] = `
+[
+  "<?xml version="1.0" encoding="utf-8"?>
+<rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:content="http://purl.org/rss/1.0/modules/content/">
+    <channel>
+        <title>Hello Blog</title>
+        <link>https://docusaurus.io/myBaseUrl/blog/</link>
+        <description>Hello Blog</description>
+        <lastBuildDate>Sun, 23 Jul 2023 00:00:00 GMT</lastBuildDate>
+        <docs>https://validator.w3.org/feed/docs/rss2.html</docs>
+        <generator>https://github.com/jpmonette/feed</generator>
+        <language>en</language>
+        <copyright>Copyright</copyright>
+        <item>
+            <title><![CDATA[test links]]></title>
+            <link>https://docusaurus.io/myBaseUrl/blog/blog-with-links/</link>
+            <guid>https://docusaurus.io/myBaseUrl/blog/blog-with-links/</guid>
+            <pubDate>Sun, 23 Jul 2023 00:00:00 GMT</pubDate>
+            <description><![CDATA[absolute full url]]></description>
+            <content:encoded><![CDATA[<p><a href="https://github.com/facebook/docusaurus" target="_blank" rel="noopener noreferrer">absolute full url</a></p>
+<p><a href="https://docusaurus.io/blog/heading-as-title">absolute pathname</a></p>
+<p><a href="https://docusaurus.io/blog/heading-as-title">relative pathname</a></p>
+<p><a href="https://docusaurus.io/blog/heading-as-title">md link</a></p>
+<p><a href="https://docusaurus.io/myBaseUrl/blog/blog-with-links/#title">anchor</a></p>
+<p><a href="https://docusaurus.io/blog/heading-as-title#title">relative pathname + anchor</a></p>
+<p><img loading="lazy" src="https://docusaurus.io/assets/images/test-image-742d39e51f41482e8132e79c09ad4eea.png" width="760" height="160" class="img_yGFe"></p>
+<p><img loading="lazy" src="https://docusaurus.io/assets/images/slash-introducing-411a16dd05086935b8e9ddae38ae9b45.svg" alt="" class="img_yGFe"></p>
+<img srcset="https://docusaurus.io/img/test-image.png 300w, https://docusaurus.io/img/docusaurus-social-card.png 500w">
+<img src="https://docusaurus.io/img/test-image.png">]]></content:encoded>
+        </item>
+        <item>
+            <title><![CDATA[MDX Blog Sample with require calls]]></title>
+            <link>https://docusaurus.io/myBaseUrl/blog/mdx-require-blog-post/</link>
+            <guid>https://docusaurus.io/myBaseUrl/blog/mdx-require-blog-post/</guid>
+            <pubDate>Sat, 06 Mar 2021 00:00:00 GMT</pubDate>
+            <description><![CDATA[Test MDX with require calls]]></description>
+            <content:encoded><![CDATA[<p>Test MDX with require calls</p>
+<!-- -->
+<!-- -->
+<img src="https://docusaurus.io/img/test-image.png">
+<img src="https://docusaurus.io/assets/images/test-image-742d39e51f41482e8132e79c09ad4eea.png">
+<img src="https://docusaurus.io/assets/images/test-image-742d39e51f41482e8132e79c09ad4eea.png">]]></content:encoded>
+        </item>
+        <item>
+            <title><![CDATA[Full Blog Sample]]></title>
+            <link>https://docusaurus.io/myBaseUrl/blog/mdx-blog-post/</link>
+            <guid>https://docusaurus.io/myBaseUrl/blog/mdx-blog-post/</guid>
+            <pubDate>Fri, 05 Mar 2021 00:00:00 GMT</pubDate>
+            <description><![CDATA[HTML Heading 1]]></description>
+            <content:encoded><![CDATA[<h1>HTML Heading 1</h1>
+<h2>HTML Heading 2</h2>
+<p>HTML Paragraph</p>
+<!-- -->
+<!-- -->
+<p>Import DOM</p>
+<h1>Heading 1</h1>
+<h2 class="anchor anchorWithHideOnScrollNavbar_G5V2" id="heading-2">Heading 2<a href="https://docusaurus.io/myBaseUrl/blog/mdx-blog-post/#heading-2" class="hash-link" aria-label="Direct link to Heading 2" title="Direct link to Heading 2">​</a></h2>
+<h3 class="anchor anchorWithHideOnScrollNavbar_G5V2" id="heading-3">Heading 3<a href="https://docusaurus.io/myBaseUrl/blog/mdx-blog-post/#heading-3" class="hash-link" aria-label="Direct link to Heading 3" title="Direct link to Heading 3">​</a></h3>
+<h4 class="anchor anchorWithHideOnScrollNavbar_G5V2" id="heading-4">Heading 4<a href="https://docusaurus.io/myBaseUrl/blog/mdx-blog-post/#heading-4" class="hash-link" aria-label="Direct link to Heading 4" title="Direct link to Heading 4">​</a></h4>
+<h5 class="anchor anchorWithHideOnScrollNavbar_G5V2" id="heading-5">Heading 5<a href="https://docusaurus.io/myBaseUrl/blog/mdx-blog-post/#heading-5" class="hash-link" aria-label="Direct link to Heading 5" title="Direct link to Heading 5">​</a></h5>
+<ul>
+<li>list1</li>
+<li>list2</li>
+<li>list3</li>
+</ul>
+<ul>
+<li>list1</li>
+<li>list2</li>
+<li>list3</li>
+</ul>
+<p>Normal Text <em>Italics Text</em> <strong>Bold Text</strong></p>
+<p><a href="https://v2.docusaurus.io/" target="_blank" rel="noopener noreferrer">link</a> <img loading="lazy" src="https://v2.docusaurus.io/" alt="image" class="img_yGFe"></p>]]></content:encoded>
+        </item>
+        <item>
+            <title><![CDATA[Complex Slug]]></title>
+            <link>https://docusaurus.io/myBaseUrl/blog/hey/my super path/héllô/</link>
+            <guid>https://docusaurus.io/myBaseUrl/blog/hey/my super path/héllô/</guid>
+            <pubDate>Sun, 16 Aug 2020 00:00:00 GMT</pubDate>
+            <description><![CDATA[complex url slug]]></description>
+            <content:encoded><![CDATA[<p>complex url slug</p>]]></content:encoded>
+            <category>date</category>
+            <category>complex</category>
+        </item>
+        <item>
+            <title><![CDATA[Simple Slug]]></title>
+            <link>https://docusaurus.io/myBaseUrl/blog/simple/slug/</link>
+            <guid>https://docusaurus.io/myBaseUrl/blog/simple/slug/</guid>
+            <pubDate>Sat, 15 Aug 2020 00:00:00 GMT</pubDate>
+            <description><![CDATA[simple url slug]]></description>
+            <content:encoded><![CDATA[<p>simple url slug</p>]]></content:encoded>
+        </item>
+        <item>
+            <title><![CDATA[some heading]]></title>
+            <link>https://docusaurus.io/myBaseUrl/blog/heading-as-title/</link>
+            <guid>https://docusaurus.io/myBaseUrl/blog/heading-as-title/</guid>
+            <pubDate>Wed, 02 Jan 2019 00:00:00 GMT</pubDate>
+        </item>
+        <item>
+            <title><![CDATA[date-matter]]></title>
+            <link>https://docusaurus.io/myBaseUrl/blog/date-matter/</link>
+            <guid>https://docusaurus.io/myBaseUrl/blog/date-matter/</guid>
+            <pubDate>Tue, 01 Jan 2019 00:00:00 GMT</pubDate>
+            <description><![CDATA[date inside front matter]]></description>
+            <content:encoded><![CDATA[<p>date inside front matter</p>]]></content:encoded>
+            <category>date</category>
+        </item>
+        <item>
+            <title><![CDATA[Happy 1st Birthday Slash! (translated)]]></title>
+            <link>https://docusaurus.io/myBaseUrl/blog/2018/12/14/Happy-First-Birthday-Slash/</link>
+            <guid>https://docusaurus.io/myBaseUrl/blog/2018/12/14/Happy-First-Birthday-Slash/</guid>
+            <pubDate>Fri, 14 Dec 2018 00:00:00 GMT</pubDate>
+            <description><![CDATA[Happy birthday! (translated)]]></description>
+            <content:encoded><![CDATA[<p>Happy birthday! (translated)</p>]]></content:encoded>
+            <author>lorber.sebastien@gmail.com (Sébastien Lorber (translated))</author>
+        </item>
+    </channel>
+</rss>",
+]
+`;

packages/docusaurus-plugin-content-blog/src/__tests__/feed.test.ts

@@ -9,6 +9,7 @@ import {jest} from '@jest/globals';
 import path from 'path';
 import fs from 'fs-extra';
 import {DEFAULT_PARSE_FRONT_MATTER} from '@docusaurus/utils';
+import {fromPartial} from '@total-typescript/shoehorn';
 import {DEFAULT_OPTIONS} from '../options';
 import {generateBlogPosts} from '../blogUtils';
 import {createBlogFeedFiles} from '../feed';
@@ -80,12 +81,12 @@ describe.each(['atom', 'rss', 'json'])('%s', (feedType) => {
     const outDir = path.join(siteDir, 'build-snap');
 
     await testGenerateFeeds(
-      {
+      fromPartial({
         siteDir,
         siteConfig,
         i18n: DefaultI18N,
         outDir,
-      } as LoadContext,
+      }),
       {
         path: 'invalid-blog-path',
         routeBasePath: 'blog',
@@ -120,12 +121,12 @@ describe.each(['atom', 'rss', 'json'])('%s', (feedType) => {
     // Build is quite difficult to mock, so we built the blog beforehand and
     // copied the output to the fixture...
     await testGenerateFeeds(
-      {
+      fromPartial({
         siteDir,
         siteConfig,
         i18n: DefaultI18N,
         outDir,
-      } as LoadContext,
+      }),
       {
         path: 'blog',
         routeBasePath: 'blog',
@@ -163,12 +164,12 @@ describe.each(['atom', 'rss', 'json'])('%s', (feedType) => {
     // Build is quite difficult to mock, so we built the blog beforehand and
     // copied the output to the fixture...
     await testGenerateFeeds(
-      {
+      fromPartial({
         siteDir,
         siteConfig,
         i18n: DefaultI18N,
         outDir,
-      } as LoadContext,
+      }),
       {
         path: 'blog',
         routeBasePath: 'blog',
@@ -216,12 +217,12 @@ describe.each(['atom', 'rss', 'json'])('%s', (feedType) => {
     // Build is quite difficult to mock, so we built the blog beforehand and
     // copied the output to the fixture...
     await testGenerateFeeds(
-      {
+      fromPartial({
         siteDir,
         siteConfig,
         i18n: DefaultI18N,
         outDir,
-      } as LoadContext,
+      }),
       {
         path: 'blog',
         routeBasePath: 'blog',
@@ -245,4 +246,48 @@ describe.each(['atom', 'rss', 'json'])('%s', (feedType) => {
     ).toMatchSnapshot();
     fsMock.mockClear();
   });
+
+  it('has feed item for each post - with trailing slash', async () => {
+    const siteDir = path.join(__dirname, '__fixtures__', 'website');
+    const outDir = path.join(siteDir, 'build-snap');
+    const siteConfig = {
+      title: 'Hello',
+      baseUrl: '/myBaseUrl/',
+      url: 'https://docusaurus.io',
+      favicon: 'image/favicon.ico',
+      trailingSlash: true,
+      markdown,
+    };
+
+    // Build is quite difficult to mock, so we built the blog beforehand and
+    // copied the output to the fixture...
+    await testGenerateFeeds(
+      fromPartial({
+        siteDir,
+        siteConfig,
+        i18n: DefaultI18N,
+        outDir,
+      }),
+      {
+        path: 'blog',
+        routeBasePath: 'blog',
+        tagsBasePath: 'tags',
+        authorsMapPath: 'authors.yml',
+        include: DEFAULT_OPTIONS.include,
+        exclude: DEFAULT_OPTIONS.exclude,
+        feedOptions: {
+          type: [feedType],
+          copyright: 'Copyright',
+        },
+        readingTime: ({content, defaultReadingTime}) =>
+          defaultReadingTime({content}),
+        truncateMarker: /<!--\s*truncate\s*-->/,
+      } as PluginOptions,
+    );
+
+    expect(
+      fsMock.mock.calls.map((call) => call[1] as string),
+    ).toMatchSnapshot();
+    fsMock.mockClear();
+  });
 });

packages/docusaurus-plugin-content-blog/src/feed.ts

@@ -11,7 +11,10 @@ import logger from '@docusaurus/logger';
 import {Feed, type Author as FeedAuthor} from 'feed';
 import * as srcset from 'srcset';
 import {normalizeUrl, readOutputHTMLFile} from '@docusaurus/utils';
-import {blogPostContainerID} from '@docusaurus/utils-common';
+import {
+  blogPostContainerID,
+  applyTrailingSlash,
+} from '@docusaurus/utils-common';
 import {load as cheerioLoad} from 'cheerio';
 import type {DocusaurusConfig} from '@docusaurus/types';
 import type {
@@ -40,8 +43,14 @@ async function generateBlogFeed({
   }
 
   const {feedOptions, routeBasePath} = options;
-  const {url: siteUrl, baseUrl, title, favicon} = siteConfig;
+  const {url: siteUrl, baseUrl, title, favicon, trailingSlash} = siteConfig;
-  const blogBaseUrl = normalizeUrl([siteUrl, baseUrl, routeBasePath]);
+  const blogBaseUrl = applyTrailingSlash(
+    normalizeUrl([siteUrl, baseUrl, routeBasePath]),
+    {
+      trailingSlash,
+      baseUrl,
+    },
+  );
 
   const blogPostsForFeed =
     feedOptions.limit === false || feedOptions.limit === null
@@ -85,7 +94,7 @@ async function defaultCreateFeedItems({
   siteConfig: DocusaurusConfig;
   outDir: string;
 }): Promise<BlogFeedItem[]> {
-  const {url: siteUrl} = siteConfig;
+  const {url: siteUrl, baseUrl, trailingSlash} = siteConfig;
 
   function toFeedAuthor(author: Author): FeedAuthor {
     return {name: author.name, link: author.url, email: author.email};
@@ -105,13 +114,19 @@ async function defaultCreateFeedItems({
       } = post;
 
       const content = await readOutputHTMLFile(
-        permalink.replace(siteConfig.baseUrl, ''),
+        permalink.replace(baseUrl, ''),
         outDir,
-        siteConfig.trailingSlash,
+        trailingSlash,
       );
       const $ = cheerioLoad(content);
 
-      const blogPostAbsoluteUrl = normalizeUrl([siteUrl, permalink]);
+      const blogPostAbsoluteUrl = applyTrailingSlash(
+        normalizeUrl([siteUrl, permalink]),
+        {
+          trailingSlash,
+          baseUrl,
+        },
+      );
 
       const toAbsoluteUrl = (src: string) =>
         String(new URL(src, blogPostAbsoluteUrl));