Updated strategy for empty newline sections

- For some reason, TinyMCE would handle empty paragraphs with a '&nbsp'
  by default but this would be removed when the paragraph had an
  attribute. This was fine in the old editor.
- This changes the approach to use '<br>' tags within elements
  for "spaced emptiness".
- For compatbility with any existing empty paragraphs, I updated the
  styles to show default height for empty paragraph sections.
- This also makes changes to help preserve encoded &nbsp; html tags
  since they were getting converted along the journey.

Related to #3302

app/Entities/Tools/PageContent.php

@@ -239,6 +239,9 @@ class PageContent
             $html .= $doc->saveHTML($childNode);
         }
 
+        // Perform required string-level tweaks
+        $html = str_replace(' ', ' ', $html);
+
         return $html;
     }
 

resources/js/wysiwyg/config.js

@@ -243,6 +243,7 @@ export function build(options) {
         remove_script_host: false,
         document_base_url: window.baseUrl('/'),
         end_container_on_empty_block: true,
+        remove_trailing_brs: false,
         statusbar: false,
         menubar: false,
         paste_data_images: false,

resources/sass/_pages.scss

@@ -164,6 +164,10 @@ body.tox-fullscreen, body.markdown-fullscreen {
     clear: both;
   }
 
+  p:empty {
+    min-height: 1.6em;
+  }
+
   &.page-revision {
     pre code {
       white-space: pre-wrap;

tests/Entity/PageContentTest.php

@@ -692,35 +692,43 @@ class PageContentTest extends TestCase
 
     public function test_base64_images_within_markdown_blanked_if_not_supported_extension_for_extract()
     {
-        $this->asEditor();
         $page = Page::query()->first();
 
-        $this->put($page->getUrl(), [
+        $this->asEditor()->put($page->getUrl(), [
             'name'     => $page->name, 'summary' => '',
             'markdown' => 'test ![test](data:image/jiff;base64,' . $this->base64Jpeg . ')',
         ]);
 
-        $page->refresh();
+        $this->assertStringContainsString('<img src=""', $page->refresh()->html);
-        $this->assertStringContainsString('<img src=""', $page->html);
     }
 
     public function test_nested_headers_gets_assigned_an_id()
     {
-        $this->asEditor();
         $page = Page::query()->first();
 
         $content = '<table><tbody><tr><td><h5>Simple Test</h5></td></tr></tbody></table>';
-        $this->put($page->getUrl(), [
+        $this->asEditor()->put($page->getUrl(), [
             'name'    => $page->name,
             'html'    => $content,
-            'summary' => '',
         ]);
 
-        $updatedPage = Page::query()->where('id', '=', $page->id)->first();
-
         // The top level <table> node will get assign the bkmrk-simple-test id because the system will
         // take the node value of h5
         // So the h5 should get the bkmrk-simple-test-1 id
-        $this->assertStringContainsString('<h5 id="bkmrk-simple-test-1">Simple Test</h5>', $updatedPage->html);
+        $this->assertStringContainsString('<h5 id="bkmrk-simple-test-1">Simple Test</h5>', $page->refresh()->html);
+    }
+
+    public function test_non_breaking_spaces_are_preserved()
+    {
+        /** @var Page $page */
+        $page = Page::query()->first();
+
+        $content = '<p>&nbsp;</p>';
+        $this->asEditor()->put($page->getUrl(), [
+            'name'    => $page->name,
+            'html'    => $content,
+        ]);
+
+        $this->assertStringContainsString('<p id="bkmrk-%C2%A0">&nbsp;</p>', $page->refresh()->html);
     }
 }