Adding upstream version 0.15.0.

Signed-off-by: Daniel Baumann <daniel@debian.org>

tests/functional_tests/test_comments.py

@@ -0,0 +1,29 @@
+import pytest
+from textual.app import App
+from textual.widgets.text_area import Selection
+from textual_textarea import TextEditor
+
+
+@pytest.mark.parametrize(
+    "language,expected_marker",
+    [
+        ("python", "# "),
+        ("sql", "-- "),
+        # ("mysql", "# "),
+        # ("c", "// "),
+    ],
+)
+@pytest.mark.asyncio
+async def test_comments(app: App, language: str, expected_marker: str) -> None:
+    async with app.run_test() as pilot:
+        ta = app.query_one("#ta", expect_type=TextEditor)
+        ta.language = language
+        original_text = "foo bar baz"
+        ta.text = original_text
+        ta.selection = Selection((0, 0), (0, 0))
+
+        await pilot.press("ctrl+underscore")  # alias for ctrl+/
+        assert ta.text == f"{expected_marker}{original_text}"
+
+        await pilot.press("ctrl+underscore")  # alias for ctrl+/
+        assert ta.text == f"{original_text}"