Backport PR #23044 on branch 6.x (PR: Fix `FoldingPanel._expand_selec…

…tion` to not select text an extra line below a folded region (Editor)) (#23046)

spyder/plugins/editor/panels/codefolding.py

@@ -709,11 +709,13 @@ def _expand_selection(self):
                 start_line in self.folding_regions
                 and self.folding_status[start_line]
             ):
-                end_line = self.folding_regions[start_line] + 1
+                end_line = self.folding_regions[start_line]
 
                 if cursor.hasSelection():
                     tc = TextHelper(self.editor).select_lines(
                         start_line, end_line)
+                    tc.movePosition(tc.MoveOperation.NextBlock,
+                                    tc.MoveMode.KeepAnchor)
 
                     if tc.selectionStart() > cursor.selectionStart():
                         start = cursor.selectionStart()

spyder/plugins/editor/widgets/codeeditor/tests/test_folding.py

@@ -28,7 +28,7 @@ def myfunc2():
         3 , 4] # Arbitary Code
     x[0] = 2 # Desired break
     print(x[1]) # Arbitary Code
-
+# don't delete this comment
 responses = {
     100: ('Continue', 'Request received, please continue'),
     101: ('Switching Protocols','Switching to new protocol'),
@@ -182,6 +182,9 @@ def fold_and_delete_region(key):
     assert "print" not in editor.toPlainText()
     assert editor.blockCount() == 31
 
+    # Check line after folded region was not removed
+    assert "# don't delete this comment" in editor.toPlainText()
+
     # Press Ctrl+Z
     qtbot.keyClick(editor, Qt.Key_Z, Qt.ControlModifier)
 
@@ -193,6 +196,9 @@ def fold_and_delete_region(key):
     assert "print" not in editor.toPlainText()
     assert editor.blockCount() == 31
 
+    # Check line after folded region was not removed
+    assert "# don't delete this comment" in editor.toPlainText()
+
     # Press Ctrl+Z again
     qtbot.keyClick(editor, Qt.Key_Z, Qt.ControlModifier)