Add tests to screen modes.

tests/test_screen_modes.py

@@ -0,0 +1,276 @@
+from functools import partial
+from itertools import cycle
+from typing import Type
+
+import pytest
+
+from textual.app import (
+    ActiveModeError,
+    App,
+    ComposeResult,
+    InvalidModeError,
+    UnknownModeError,
+)
+from textual.screen import ModalScreen, Screen
+from textual.widgets import Footer, Header, Label, TextLog
+
+FRUITS = cycle("apple mango strawberry banana peach pear melon watermelon".split())
+
+
+class ScreenBindingsMixin(Screen[None]):
+    BINDINGS = [
+        ("1", "one", "Mode 1"),
+        ("2", "two", "Mode 2"),
+        ("p", "push", "Push rnd scrn"),
+        ("o", "pop_screen", "Pop"),
+        ("r", "remove", "Remove mode 1"),
+    ]
+
+    def action_one(self) -> None:
+        self.app.switch_mode("one")
+
+    def action_two(self) -> None:
+        self.app.switch_mode("two")
+
+    def action_fruits(self) -> None:
+        self.app.switch_mode("fruits")
+
+    def action_push(self) -> None:
+        self.app.push_screen(FruitModal())
+
+
+class BaseScreen(ScreenBindingsMixin):
+    def __init__(self, label):
+        super().__init__()
+        self.label = label
+
+    def compose(self) -> ComposeResult:
+        yield Header()
+        yield Label(self.label)
+        yield Footer()
+
+    def action_remove(self) -> None:
+        self.app.remove_mode("one")
+
+
+class FruitModal(ModalScreen[str], ScreenBindingsMixin):
+    BINDINGS = [("d", "dismiss_fruit", "Dismiss")]
+
+    def compose(self) -> ComposeResult:
+        yield Label(next(FRUITS))
+
+
+class FruitsScreen(ScreenBindingsMixin):
+    def compose(self) -> ComposeResult:
+        yield TextLog()
+
+
+@pytest.fixture
+def ModesApp():
+    class ModesApp(App[None]):
+        MODES = {
+            "one": lambda: BaseScreen("one"),
+            "two": "screen_two",
+        }
+
+        SCREENS = {
+            "screen_two": lambda: BaseScreen("two"),
+        }
+
+        def on_mount(self):
+            self.switch_mode("one")
+
+    return ModesApp
+
+
+async def test_mode_setup(ModesApp: Type[App]):
+    app = ModesApp()
+    async with app.run_test():
+        assert isinstance(app.screen, BaseScreen)
+        assert str(app.screen.query_one(Label).renderable) == "one"
+
+
+async def test_switch_mode(ModesApp: Type[App]):
+    app = ModesApp()
+    async with app.run_test() as pilot:
+        await pilot.press("2")
+        assert str(app.screen.query_one(Label).renderable) == "two"
+        await pilot.press("1")
+        assert str(app.screen.query_one(Label).renderable) == "one"
+
+
+async def test_switch_same_mode(ModesApp: Type[App]):
+    app = ModesApp()
+    async with app.run_test() as pilot:
+        await pilot.press("1")
+        assert str(app.screen.query_one(Label).renderable) == "one"
+        await pilot.press("1")
+        assert str(app.screen.query_one(Label).renderable) == "one"
+
+
+async def test_switch_unknown_mode(ModesApp: Type[App]):
+    app = ModesApp()
+    async with app.run_test():
+        with pytest.raises(UnknownModeError):
+            app.switch_mode("unknown mode here")
+
+
+async def test_remove_mode(ModesApp: Type[App]):
+    app = ModesApp()
+    async with app.run_test() as pilot:
+        app.switch_mode("two")
+        await pilot.pause()
+        assert str(app.screen.query_one(Label).renderable) == "two"
+        app.remove_mode("one")
+        assert "one" not in app.MODES
+
+
+async def test_remove_active_mode(ModesApp: Type[App]):
+    app = ModesApp()
+    async with app.run_test():
+        with pytest.raises(ActiveModeError):
+            app.remove_mode("one")
+
+
+async def test_add_mode(ModesApp: Type[App]):
+    app = ModesApp()
+    async with app.run_test() as pilot:
+        app.add_mode("three", BaseScreen("three"))
+        app.switch_mode("three")
+        await pilot.pause()
+        assert str(app.screen.query_one(Label).renderable) == "three"
+
+
+async def test_add_mode_duplicated(ModesApp: Type[App]):
+    app = ModesApp()
+    async with app.run_test():
+        with pytest.raises(InvalidModeError):
+            app.add_mode("one", BaseScreen("one"))
+
+
+async def test_screen_stack_preserved(ModesApp: Type[App]):
+    fruits = []
+    N = 5
+
+    app = ModesApp()
+    async with app.run_test() as pilot:
+        # Build the stack up.
+        for _ in range(N):
+            await pilot.press("p")
+            fruits.append(str(app.query_one(Label).renderable))
+
+        assert len(app.screen_stack) == N + 1
+
+        # Switch out and back.
+        await pilot.press("2")
+        assert len(app.screen_stack) == 1
+        await pilot.press("1")
+
+        # Check the stack.
+        assert len(app.screen_stack) == N + 1
+        for _ in range(N):
+            assert str(app.query_one(Label).renderable) == fruits.pop()
+            await pilot.press("o")
+
+
+async def test_inactive_stack_is_alive():
+    class FastCounter(Screen[None]):
+        def compose(self) -> ComposeResult:
+            self.lbl = Label("0")
+            yield self.lbl
+
+        def on_mount(self) -> None:
+            self.set_interval(0.01, self.increment)
+
+        def increment(self) -> None:
+            self.lbl.update(str(int(str(self.lbl.renderable)) + 1))
+
+        def key_s(self):
+            self.app.switch_mode("smile")
+
+    class SmileScreen(Screen[None]):
+        def compose(self) -> ComposeResult:
+            yield Label(":)")
+
+        def key_s(self):
+            self.app.switch_mode("fast")
+
+    class ModesApp(App[None]):
+        MODES = {
+            "fast": FastCounter,
+            "smile": SmileScreen,
+        }
+
+        def on_mount(self) -> None:
+            self.switch_mode("fast")
+
+    app = ModesApp()
+    async with app.run_test() as pilot:
+        current = int(str(app.query_one(Label).renderable))
+        await pilot.press("s")
+        assert str(app.query_one(Label).renderable) == ":)"
+        await pilot.press("s")
+        assert int(str(app.query_one(Label).renderable)) > current
+
+
+async def test_multiple_mode_callbacks():
+    written = []
+
+    class LogScreen(Screen[None]):
+        def __init__(self, value):
+            super().__init__()
+            self.value = value
+
+        def key_p(self) -> None:
+            self.app.push_screen(ResultScreen(self.value), written.append)
+
+    class ResultScreen(Screen[str]):
+        def __init__(self, value):
+            super().__init__()
+            self.value = value
+
+        def key_p(self) -> None:
+            self.dismiss(self.value)
+
+        def key_f(self) -> None:
+            self.app.switch_mode("first")
+
+        def key_o(self) -> None:
+            self.app.switch_mode("other")
+
+    class ModesApp(App[None]):
+        MODES = {
+            "first": lambda: LogScreen("first"),
+            "other": lambda: LogScreen("other"),
+        }
+
+        def on_mount(self) -> None:
+            self.switch_mode("first")
+
+        def key_f(self) -> None:
+            self.switch_mode("first")
+
+        def key_o(self) -> None:
+            self.switch_mode("other")
+
+    app = ModesApp()
+    async with app.run_test() as pilot:
+        # Push and dismiss ResultScreen("first")
+        await pilot.press("p")
+        await pilot.press("p")
+        assert written == ["first"]
+
+        # Push ResultScreen("first")
+        await pilot.press("p")
+        # Switch to LogScreen("other")
+        await pilot.press("o")
+        # Push and dismiss ResultScreen("other")
+        await pilot.press("p")
+        await pilot.press("p")
+        assert written == ["first", "other"]
+
+        # Go back to ResultScreen("first")
+        await pilot.press("f")
+        # Dismiss ResultScreen("first")
+        await pilot.press("p")
+        assert written == ["first", "other", "first"]