Add unit tests for selection list messages

tests/selection_list/test_selection_messages.py

@@ -0,0 +1,194 @@
+"""Unit tests aimed at testing the selection list messages.
+
+Note that these tests only cover a subset of the public API of this widget.
+The bulk of the API is inherited from OptionList, and as such there are
+comprehensive tests for that. These tests simply cover the parts of the API
+that have been modified by the child class.
+"""
+
+from __future__ import annotations
+
+from textual import on
+from textual.app import App, ComposeResult
+from textual.messages import Message
+from textual.widgets import SelectionList
+
+
+class SelectionListApp(App[None]):
+    """Test selection list application."""
+
+    def __init__(self) -> None:
+        super().__init__()
+        self.messages: list[tuple[str, int | None]] = []
+
+    def compose(self) -> ComposeResult:
+        yield SelectionList[int](*[(str(n), n) for n in range(10)])
+
+    @on(SelectionList.SelectionHighlighted)
+    @on(SelectionList.SelectionToggled)
+    @on(SelectionList.SelectedChanged)
+    def _record(self, event: Message) -> None:
+        self.messages.append(
+            (
+                event.__class__.__name__,
+                event.selection_index
+                if isinstance(event, SelectionList.SelectionMessage)
+                else None,
+            )
+        )
+
+
+async def test_messages_on_startup() -> None:
+    """There should be a highlighted message when a non-empty selection list first starts up."""
+    async with SelectionListApp().run_test() as pilot:
+        assert isinstance(pilot.app, SelectionListApp)
+        await pilot.pause()
+        assert pilot.app.messages == [("SelectionHighlighted", 0)]
+
+
+async def test_new_highlight() -> None:
+    """Setting the highlight to a new option should result in a message."""
+    async with SelectionListApp().run_test() as pilot:
+        assert isinstance(pilot.app, SelectionListApp)
+        await pilot.pause()
+        pilot.app.query_one(SelectionList).highlighted = 2
+        await pilot.pause()
+        assert pilot.app.messages[1:] == [("SelectionHighlighted", 2)]
+
+
+async def test_toggle() -> None:
+    """Toggling an option should result in messages."""
+    async with SelectionListApp().run_test() as pilot:
+        assert isinstance(pilot.app, SelectionListApp)
+        await pilot.pause()
+        pilot.app.query_one(SelectionList).toggle(0)
+        await pilot.pause()
+        assert pilot.app.messages == [
+            ("SelectionHighlighted", 0),
+            ("SelectedChanged", None),
+        ]
+
+
+async def test_toggle_all() -> None:
+    """Toggling all options should result in messages."""
+    async with SelectionListApp().run_test() as pilot:
+        assert isinstance(pilot.app, SelectionListApp)
+        await pilot.pause()
+        pilot.app.query_one(SelectionList).toggle_all()
+        await pilot.pause()
+        assert pilot.app.messages == [
+            ("SelectionHighlighted", 0),
+            ("SelectedChanged", None),
+        ]
+
+
+async def test_select() -> None:
+    """Selecting all an option should result in a message."""
+    async with SelectionListApp().run_test() as pilot:
+        assert isinstance(pilot.app, SelectionListApp)
+        await pilot.pause()
+        pilot.app.query_one(SelectionList).select(1)
+        await pilot.pause()
+        assert pilot.app.messages == [
+            ("SelectionHighlighted", 0),
+            ("SelectedChanged", None),
+        ]
+
+
+async def test_select_selected() -> None:
+    """Selecting an option that is already selected should emit no extra message.."""
+    async with SelectionListApp().run_test() as pilot:
+        assert isinstance(pilot.app, SelectionListApp)
+        await pilot.pause()
+        pilot.app.query_one(SelectionList).select(0)
+        await pilot.pause()
+        pilot.app.query_one(SelectionList).select(0)
+        await pilot.pause()
+        assert pilot.app.messages == [
+            ("SelectionHighlighted", 0),
+            ("SelectedChanged", None),
+        ]
+
+
+async def test_select_all() -> None:
+    """Selecting all options should result in messages."""
+    async with SelectionListApp().run_test() as pilot:
+        assert isinstance(pilot.app, SelectionListApp)
+        await pilot.pause()
+        pilot.app.query_one(SelectionList).select_all()
+        await pilot.pause()
+        assert pilot.app.messages == [
+            ("SelectionHighlighted", 0),
+            ("SelectedChanged", None),
+        ]
+
+
+async def test_select_all_selected() -> None:
+    """Selecting all when all are selected should result in no extra messages."""
+    async with SelectionListApp().run_test() as pilot:
+        assert isinstance(pilot.app, SelectionListApp)
+        await pilot.pause()
+        pilot.app.query_one(SelectionList).select_all()
+        await pilot.pause()
+        pilot.app.query_one(SelectionList).select_all()
+        await pilot.pause()
+        assert pilot.app.messages == [
+            ("SelectionHighlighted", 0),
+            ("SelectedChanged", None),
+        ]
+
+
+async def test_deselect() -> None:
+    """Deselecting an option should result in a message."""
+    async with SelectionListApp().run_test() as pilot:
+        assert isinstance(pilot.app, SelectionListApp)
+        await pilot.pause()
+        pilot.app.query_one(SelectionList).select(1)
+        await pilot.pause()
+        pilot.app.query_one(SelectionList).deselect(1)
+        await pilot.pause()
+        assert pilot.app.messages == [
+            ("SelectionHighlighted", 0),
+            ("SelectedChanged", None),
+            ("SelectedChanged", None),
+        ]
+
+
+async def test_deselect_deselected() -> None:
+    """Deselecting a deslected option should result in no extra messages."""
+    async with SelectionListApp().run_test() as pilot:
+        assert isinstance(pilot.app, SelectionListApp)
+        await pilot.pause()
+        pilot.app.query_one(SelectionList).deselect(0)
+        await pilot.pause()
+        assert pilot.app.messages == [("SelectionHighlighted", 0)]
+
+
+async def test_deselect_all() -> None:
+    """Deselecting all options should result in no additional."""
+    async with SelectionListApp().run_test() as pilot:
+        assert isinstance(pilot.app, SelectionListApp)
+        await pilot.pause()
+        pilot.app.query_one(SelectionList).deselect_all()
+        await pilot.pause()
+        assert pilot.app.messages == [("SelectionHighlighted", 0)]
+
+
+async def test_select_then_deselect_all() -> None:
+    """Selecting and then deselecting all options should result in messages."""
+    async with SelectionListApp().run_test() as pilot:
+        assert isinstance(pilot.app, SelectionListApp)
+        await pilot.pause()
+        pilot.app.query_one(SelectionList).select_all()
+        await pilot.pause()
+        assert pilot.app.messages == [
+            ("SelectionHighlighted", 0),
+            ("SelectedChanged", None),
+        ]
+        pilot.app.query_one(SelectionList).deselect_all()
+        await pilot.pause()
+        assert pilot.app.messages == [
+            ("SelectionHighlighted", 0),
+            ("SelectedChanged", None),
+            ("SelectedChanged", None),
+        ]