From b358353cf8c247a097e349715c5a0ff4da9bf438 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Felix=20B=C3=B6hm?= <188768+fb55@users.noreply.github.com>
Date: Fri, 4 Feb 2022 21:18:01 -0600
Subject: [PATCH] fix: `serialize` top-level template contents

Before this, passing a `template` tag to `serialize` would result in an empty string.
---
 packages/parse5/lib/serializer/index.test.ts |  9 +++++++++
 packages/parse5/lib/serializer/index.ts      | 17 +++++++++--------
 2 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/packages/parse5/lib/serializer/index.test.ts b/packages/parse5/lib/serializer/index.test.ts
index d5ae55fa0..3d05023bd 100644
--- a/packages/parse5/lib/serializer/index.test.ts
+++ b/packages/parse5/lib/serializer/index.test.ts
@@ -34,4 +34,13 @@ describe('serializer', () => {
             assert.equal(html, '<div><button>Hello</button></div>');
         });
     });
+
+    it('serializes <template> elements inner content', () => {
+        const document = parse5.parseFragment('<template><button>Hello</button></template>');
+        const template = document.childNodes[0];
+        assert.ok(isElementNode(template));
+        const html = parse5.serialize(template);
+
+        assert.equal(html, '<button>Hello</button>');
+    });
 });
diff --git a/packages/parse5/lib/serializer/index.ts b/packages/parse5/lib/serializer/index.ts
index 6019a0286..65a9ca57b 100644
--- a/packages/parse5/lib/serializer/index.ts
+++ b/packages/parse5/lib/serializer/index.ts
@@ -114,7 +114,14 @@ function serializeChildNodes<T extends TreeAdapterTypeMap>(
     options: InternalOptions<T>
 ): string {
     let html = '';
-    const childNodes = options.treeAdapter.getChildNodes(parentNode);
+    // Get container of the child nodes
+    const container =
+        options.treeAdapter.isElementNode(parentNode) &&
+        options.treeAdapter.getTagName(parentNode) === $.TEMPLATE &&
+        options.treeAdapter.getNamespaceURI(parentNode) === NS.HTML
+            ? options.treeAdapter.getTemplateContent(parentNode)
+            : parentNode;
+    const childNodes = options.treeAdapter.getChildNodes(container);
 
     if (childNodes) {
         for (const currentNode of childNodes) {
@@ -139,13 +146,7 @@ function serializeElement<T extends TreeAdapterTypeMap>(node: T['element'], opti
     return `<${tn}${serializeAttributes(node, options)}>${
         options.treeAdapter.getNamespaceURI(node) === NS.HTML && VOID_ELEMENTS.has(tn)
             ? ''
-            : `${serializeChildNodes(
-                  // Get container of the child nodes
-                  tn === $.TEMPLATE && options.treeAdapter.getNamespaceURI(node) === NS.HTML
-                      ? options.treeAdapter.getTemplateContent(node)
-                      : node,
-                  options
-              )}</${tn}>`
+            : `${serializeChildNodes(node, options)}</${tn}>`
     }`;
 }