text selection test

Author: willmcgugan

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Fixed
 
 - Fixed type hint aliasing for App under TYPE_CHECKING https://github.com/Textualize/textual/pull/6152
+- Fixed for text selection with double width characters https://github.com/Textualize/textual/pull/6186
 
 ### Changed
 

src/textual/screen.py

@@ -1738,7 +1738,6 @@ def _watch__select_end(
         Args:
             select_end: The end selection.
         """
-
         if select_end is None or self._select_start is None:
             # Nothing to select
             return

src/textual/selection.py

@@ -56,12 +56,12 @@ def extract(self, text: str) -> str:
             return lines[start_line][start_offset:end_offset]
 
         selection: list[str] = []
-        selected_lines = lines[start_line:end_line]
+        selected_lines = lines[start_line : end_line + 1]
         if len(selected_lines) >= 2:
             first_line, *mid_lines, last_line = selected_lines
             selection.append(first_line[start_offset:])
             selection.extend(mid_lines)
-            selection.append(last_line[: end_offset + 1])
+            selection.append(last_line[:end_offset])
         else:
             return lines[start_line][start_offset:end_offset]
         return "\n".join(selection)

tests/test_selection.py

@@ -1,7 +1,9 @@
 import pytest
 
+from textual.app import App, ComposeResult
 from textual.geometry import Offset
 from textual.selection import Selection
+from textual.widgets import Static
 
 
 @pytest.mark.parametrize(
@@ -20,3 +22,24 @@
 def test_extract(text: str, selection: Selection, expected: str) -> None:
     """Test Selection.extract"""
     assert selection.extract(text) == expected
+
+
+async def test_double_width():
+    """Test that selection works with double width characters."""
+
+    TEXT = """😂❤️👍Select😊🙏😍\nme🔥💯😭😂❤️👍"""
+
+    class TextSelectApp(App):
+        def compose(self) -> ComposeResult:
+            yield Static(TEXT)
+
+    app = TextSelectApp()
+    async with app.run_test() as pilot:
+        await pilot.pause()
+        assert await pilot.mouse_down(offset=(2, 0))
+        await pilot.pause()
+        assert await pilot.mouse_up(offset=(7, 1))
+        selected_text = app.screen.get_selected_text()
+        expected = "❤️👍Select😊🙏😍\nme🔥💯😭"
+
+    assert selected_text == expected