Extra new line inserted in markdown code block

[morremeyer]

Description:

Until recent versions (I don't remember which one, sorry), code markup could be done as follows:

```
Text
```

which displayed as

Text

This behviour changed, as

```
Text
```

now displays as

Text

and you need

```Text
```

for

Text

This is really annoying as all other markdown implementations (at least known to me), e.g. GitHubs own ignore that newline after the ```.

Maybe this need discussion, I'm not sure of that.

Server Setup Information:

• Version of Rocket.Chat Server: 0.57.2
• Operating System: Mac OS Sierra 10.12.6
• Deployment Method(snap/docker/tar/etc): unknown
• Number of Running Instances: 1
• DB Replicaset Oplog: unknown
• Local Version: 2.8.0

Steps to Reproduce:

1. Paste one of the above examples in your Rocket.Chat
2. See the described behaviour

Expected behavior:

No change in behaviour the following should work as it did earlier:

```
Text
```

which displayed as

Text

Actual behavior:

It works as follows:

```Text
```

for

Text

[fnkr]

CommonMark also say's it should be rendered like

this

http://spec.commonmark.org/0.28/#fenced-code-blocks

[xenithorb]

I think this should be re-categorized as a proper bug, and re-titled "Markdown code fencing produces extra newline"

[xenithorb]

Inner HTML for the pre's:

``` on same line:

<code class="code-colors hljs subunit"><span class="copyonly">```<br></span><span class="hljs-keyword">test
</span><span class="copyonly"><br>```</span></code>

With extra space:

<code class="code-colors hljs subunit"><span class="copyonly">```<br></span>
<span class="hljs-keyword">test
</span><span class="copyonly"><br>```</span></code>

So I'm guessing we either need to stop sending extra <br>s or we need to strip leading newlines from the input. Remember these are encased in <pre> tags, so the line breaks are going to render. The actual markup itself is identical minus the linefeed.

[morremeyer]

@xenithorb I fully agree with that. I prefer the "stop sending extra <br> solution" as it looks cleaner to me.

[xenithorb]

1. It only happens with the original markdown parser

2. Because of that, I believe the bug is on this line: https://github.com/RocketChat/Rocket.Chat/blob/develop/packages/rocketchat-markdown/parser/original/code.js#L61
   I would fix it but I'm not good with JS, and I'm not certain what the team's goal here would be in a "proper fix"

   i.e. you could probably just remove the <br> in this span:

   <span class='copyonly'>\`\`\`<br></span>

[graywolf336]

There was a pull request to fix this, but I can't find it now for some reason...

[xenithorb]

@graywolf336 #8510 Found it

Perhaps triage #9754 to go along with this fix too?