Bug 1606232 - Make `nsIHTMLEditor::GetSelectedElement()` check whether the found element is followed by `<br>` element deeper r=m_kato

Current `nsIHTMLEditor::GetSelectedElement()` just checks whether the
found element is followed by `<br>` element or not.  However, following
element may start with `<br>` element and if there is end of the range,
`PostContentIterator` does not list up the `<br>` element.

Therefore, it should check whether the found element is followed by
`<br>` element which is starts the next sibling element too.

Differential Revision: https://phabricator.services.mozilla.com/D60385

--HG--
extra : moz-landing-system : lando

editor/libeditor/HTMLEditor.cpp

@@ -2605,9 +2605,20 @@ already_AddRefed<Element> HTMLEditor::GetSelectedElement(const nsAtom* aTagName,
     // - <p><b>[def</b>}<br></p>
     // Note that we don't need special handling for <a href> because double
     // clicking it selects the element and we use the first path to handle it.
-    if (lastElementInRange->GetNextSibling() &&
-        lastElementInRange->GetNextSibling()->IsHTMLElement(nsGkAtoms::br)) {
-      return nullptr;
+    // Additionally, we have this case too:
+    // - <p><b>[def</b><b>}<br></b></p>
+    // In these cases, the <br> element is not listed up by PostContentIterator.
+    // So, we should return nullptr if next sibling is a `<br>` element or
+    // next sibling starts with `<br>` element.
+    if (nsIContent* nextSibling = lastElementInRange->GetNextSibling()) {
+      if (nextSibling->IsHTMLElement(nsGkAtoms::br)) {
+        return nullptr;
+      }
+      nsIContent* firstEditableLeaf = GetLeftmostChild(nextSibling);
+      if (firstEditableLeaf &&
+          firstEditableLeaf->IsHTMLElement(nsGkAtoms::br)) {
+        return nullptr;
+      }
     }
 
     if (!aTagName) {

editor/libeditor/tests/test_nsIHTMLEditor_getSelectedElement.html

@@ -779,6 +779,27 @@ SimpleTest.waitForFocus(async function() {
      null,
      "#9-1 nsIHTMLEditor::getSelectedElement(\"anchor\") should return null when Selection starts from a text node in <b> element and ends before the following <br> element");
 
+  editor.innerHTML = "<p><b>b1</b><b><br></b><b>b2</b></p>";
+  editor.focus();
+
+  // <p><b>[b1</b><b>}<br></b><b>b2</b></p>
+  // This is usual case of double-clicking in the first <b> element.
+  range = document.createRange();
+  range.setStart(editor.firstChild.firstChild.firstChild, 0);
+  range.setEnd(editor.firstChild.firstChild.nextSibling, 0);
+  selection.removeAllRanges();
+  selection.addRange(range);
+
+  is(SpecialPowers.unwrap(getHTMLEditor().getSelectedElement("")),
+     null,
+     "#10-1 nsIHTMLEditor::getSelectedElement(\"\") should return null when Selection starts from a text node in <b> element and ends before the following <br> element in another <b> element");
+  is(SpecialPowers.unwrap(getHTMLEditor().getSelectedElement("href")),
+     null,
+     "#10-1 nsIHTMLEditor::getSelectedElement(\"href\") should return null when Selection starts from a text node in <b> element and ends before the following <br> element in another <b> element");
+  is(SpecialPowers.unwrap(getHTMLEditor().getSelectedElement("anchor")),
+     null,
+     "#10-1 nsIHTMLEditor::getSelectedElement(\"anchor\") should return null when Selection starts from a text node in <b> element and ends before the following <br> element in another <b> element");
+
   SimpleTest.finish();
 });