Desktop: Fixes #8430: Make HTML <br/> tags convert to markdown compatible with the softbreaks setting (#8469)

packages/app-cli/tests/html_to_md/linebreaks.html

@@ -0,0 +1,10 @@
+<h1>Linebreaks</h1>
+<div>&lt;br&gt;-style linebreaks should be replaced with two spaces followed by a
+	newline.<br/>This allows the generated mark<br/>down to render to equivalent HTML
+	even if the <code>markdown.plugin.softbreaks</code> setting is enabled.</div>
+<pre class="some-code" style="font-family:monospace;">&lt;br&gt;s shouldn't<br/>lead<br/>to trailing spaces in
+code
+however.
+</pre>
+<p>Because it isn't</p>
+<div>necessary.<br/><br/><br/><br/>...</div>

packages/app-cli/tests/html_to_md/linebreaks.md

@@ -0,0 +1,21 @@
+# Linebreaks
+
+<br>-style linebreaks should be replaced with two spaces followed by a newline.  
+This allows the generated mark  
+down to render to equivalent HTML even if the `markdown.plugin.softbreaks` setting is enabled.
+
+```
+<br>s shouldn't
+lead
+to trailing spaces in
+code
+however.
+```
+
+Because it isn't
+
+necessary.  
+  
+  
+  
+...

packages/lib/HtmlToMd.ts

@@ -23,7 +23,12 @@ export default class HtmlToMd {
 			bulletListMarker: '-',
 			emDelimiter: '*',
 			strongDelimiter: '**',
-			br: '',
+
+			// If soft-breaks are enabled, lines need to end with two or more spaces for
+			// trailing <br/>s to render. See
+			// https://github.com/laurent22/joplin/issues/8430
+			br: '  ',
+
 			disableEscapeContent: 'disableEscapeContent' in options ? options.disableEscapeContent : false,
 		};
 		if (options.convertEmbeddedPdfsToLinks) {

packages/turndown/src/commonmark-rules.js

@@ -33,7 +33,10 @@ rules.lineBreak = {
   filter: 'br',
 
   replacement: function (content, node, options) {
-    return options.br + '\n'
+    // Code blocks may include <br/>s -- replacing them should not be necessary
+    // in code blocks.
+    const brReplacement = node.isCode ? '' : options.br;
+    return brReplacement + '\n'
   }
 }