From 481924b34d23b0ce435778cce7bce77571b22f9d Mon Sep 17 00:00:00 2001
From: Abdullah Diab <mpcabd@gmail.com>
Date: Sat, 29 Jul 2017 20:52:45 +0200
Subject: [PATCH] helpers: Fix broken TaskList in Markdown

As per the referenced issue, if the task list in Markdown has
nothing before it, it will be rendered wrongly:

```
---
title: "My First Post"
date: 2017-07-29T20:21:57+02:00
draft: true
---

* [ ] TaskList

```

is rendered as:

```
<ul> class="task-list"
<li><input type="checkbox" disabled class="task-list-item"> TaskList</li>
</ul>
```

The problem lies in the `List` function of `HugoHTMLRenderer`, it had
a hardocded index of `4` for the first `>` of the list, it is used to
insert the class into the text before the closing bracket, but that
hardcoded index is only right when there is a newline before the
opening bracket, which is the case when there is anything in the
document before the task list, but if there is nothing, then there is
no newline, and the correct index of the first `>` will be `3`.

To fix that we're changing the hardcoded index to be dynamic by using
`bytes.Index` to find it properly. We're also adding a test case to
make sure this is tested against.

Fixes #3710
---
 helpers/content_renderer.go      | 6 +++++-
 helpers/content_renderer_test.go | 8 ++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/helpers/content_renderer.go b/helpers/content_renderer.go
index f0d8cda12af..376351f7a04 100644
--- a/helpers/content_renderer.go
+++ b/helpers/content_renderer.go
@@ -101,10 +101,14 @@ func (r *HugoHTMLRenderer) List(out *bytes.Buffer, text func() bool, flags int)
 	if out.Len() > marker {
 		list := out.Bytes()[marker:]
 		if bytes.Contains(list, []byte("task-list-item")) {
+			// Find the index of the first >, it might be 3 or 4 depending on whether
+			// there is a new line at the start, but this is safer than just hardcoding it.
+			closingBracketIndex := bytes.Index(list, []byte(">"))
 			// Rewrite the buffer from the marker
 			out.Truncate(marker)
+			// Safely assuming closingBracketIndex won't be -1 since there is a list
 			// May be either dl, ul or ol
-			list := append(list[:4], append([]byte(` class="task-list"`), list[4:]...)...)
+			list := append(list[:closingBracketIndex], append([]byte(` class="task-list"`), list[closingBracketIndex:]...)...)
 			out.Write(list)
 		}
 	}
diff --git a/helpers/content_renderer_test.go b/helpers/content_renderer_test.go
index 2f155de071f..63e681d97b9 100644
--- a/helpers/content_renderer_test.go
+++ b/helpers/content_renderer_test.go
@@ -118,6 +118,14 @@ END
 		{`- [x] On1`, false, `<ul>
 <li>[x] On1</li>
 </ul>
+`},
+		{`* [ ] Off
+
+END`, true, `<ul class="task-list">
+<li><input type="checkbox" disabled class="task-list-item"> Off</li>
+</ul>
+
+<p>END</p>
 `},
 	} {
 		blackFridayConfig := c.NewBlackfriday()