Catch un-renderable slide content at runtime (#202)

docs/changelog.md

@@ -4,6 +4,10 @@
 
 ## `0.4.5` | *Unreleased*
 
+### Fixed
+
+- [#202](https://github.com/JoshKarpel/spiel/pull/202) Returning un-renderable content from a slide content function now displays an error instead of crashing Spiel.
+
 ### Changed
 
 - [#203](https://github.com/JoshKarpel/spiel/pull/203) The `Image` example in the demo deck is now centered inside its `Panel`.

docs/generate_screenshots.py

@@ -14,6 +14,7 @@ from rich.console import Console
 from textual.app import App
 from textual.pilot import Pilot
 
+import spiel.constants
 from spiel.app import SpielApp
 
 ROOT_DIR = Path(__file__).resolve().parent.parent
@@ -71,7 +72,7 @@ def take_screenshot(name: str, deck_file: Path, size: tuple[int, int], keys: Ite
 if __name__ == "__main__":
     start_time = monotonic()
 
-    demo_deck = ROOT_DIR / "spiel" / "demo" / "demo.py"
+    demo_deck = spiel.constants.DEMO_FILE
     quickstart_deck = ROOT_DIR / "docs" / "examples" / "quickstart.py"
     slide_via_decorator = ROOT_DIR / "docs" / "examples" / "slide_via_decorator.py"
     slide_loop = ROOT_DIR / "docs" / "examples" / "slide_loop.py"

poetry.lock

@@ -1252,6 +1252,25 @@ tomli = {version = ">=1.0.0", markers = "python_version < \"3.11\""}
 [package.extras]
 testing = ["argcomplete", "hypothesis (>=3.56)", "mock", "nose", "pygments (>=2.7.2)", "requests", "xmlschema"]
 
+[[package]]
+name = "pytest-asyncio"
+version = "0.20.3"
+description = "Pytest support for asyncio"
+category = "dev"
+optional = false
+python-versions = ">=3.7"
+files = [
+    {file = "pytest-asyncio-0.20.3.tar.gz", hash = "sha256:83cbf01169ce3e8eb71c6c278ccb0574d1a7a3bb8eaaf5e50e0ad342afb33b36"},
+    {file = "pytest_asyncio-0.20.3-py3-none-any.whl", hash = "sha256:f129998b209d04fcc65c96fc85c11e5316738358909a8399e93be553d7656442"},
+]
+
+[package.dependencies]
+pytest = ">=6.1.0"
+
+[package.extras]
+docs = ["sphinx (>=5.3)", "sphinx-rtd-theme (>=1.0)"]
+testing = ["coverage (>=6.2)", "flaky (>=3.5.0)", "hypothesis (>=5.7.1)", "mypy (>=0.931)", "pytest-trio (>=0.7.0)"]
+
 [[package]]
 name = "pytest-cov"
 version = "4.0.0"
@@ -1888,4 +1907,4 @@ testing = ["flake8 (<5)", "func-timeout", "jaraco.functools", "jaraco.itertools"
 [metadata]
 lock-version = "2.0"
 python-versions = ">=3.10,<4"
-content-hash = "bf60d897bc813695779b088ad843a789041cdfc39dc376f0aac71a42f3a01cb8"
+content-hash = "1ea15a591ae6a2e7f0ca7b4395d5b249f8591085f8918f6643b6ef265b3db5d2"

pyproject.toml

@@ -59,6 +59,7 @@ textual = {extras = ["dev"], version = "==0.4.0"}
 mkdocs = ">=1.4"
 mkdocs-material = ">=9"
 mkdocstrings = {extras = ["python"], version = ">=0.19.0"}
+pytest-asyncio = ">=0.20"
 
 [tool.poetry.scripts]
 spiel = 'spiel.cli:cli'
@@ -78,11 +79,15 @@ all = true
 addopts = ["--strict-markers", "--mypy", "-n", "auto"]
 testpaths = ["tests", "spiel", "docs"]
 
+markers = ["slow"]
+
+asyncio_mode = "auto"
+
 [tool.mypy]
 pretty = false
 show_error_codes = true
 
-files = ["spiel/**/*.py", "tests/**/*.py"]
+files = ["."]
 
 check_untyped_defs = true
 disallow_incomplete_defs = true

spiel/app.py

@@ -79,7 +79,7 @@ class SpielApp(App[None]):
     def __init__(
         self,
         deck_path: Path,
-        watch_path: Path,
+        watch_path: Path | None = None,
         show_messages: bool = True,
         fixed_time: datetime.datetime | None = None,
     ):
@@ -101,6 +101,9 @@ class SpielApp(App[None]):
         await self.push_screen("slide")
 
     async def reload(self) -> None:
+        if self.watch_path is None:
+            return
+
         log(f"Watching {self.watch_path} for changes")
         async for changes in awatch(self.watch_path):
             change_msg = "\n  ".join([""] + [f"{k.raw_str()}: {v}" for k, v in changes])

spiel/demo/demo.py

@@ -426,6 +426,8 @@ def failure() -> RenderableType:
         When this happens, Spiel will display the stack trace to help you debug the problem.
 
         Deck reloading will still happen, so you can fix the error without stopping Spiel.
+
+        This error display will also be shown if you return slide content that can't be rendered by Rich.
         """
     )
 

spiel/widgets/slide.py

@@ -5,7 +5,9 @@ from time import monotonic
 
 from rich.box import HEAVY
 from rich.console import RenderableType
+from rich.errors import NotRenderableError
 from rich.panel import Panel
+from rich.protocol import is_renderable
 from rich.style import Style
 from rich.traceback import Traceback
 from textual.reactive import reactive
@@ -30,8 +32,11 @@ class SlideWidget(SpielWidget):
     def render(self) -> RenderableType:
         try:
             self.remove_class("error")
-            slide = self.app.deck[self.app.current_slide_idx]
-            return slide.render(triggers=self.triggers)
+            r = self.current_slide.render(triggers=self.triggers)
+            if is_renderable(r):
+                return r
+            else:
+                raise NotRenderableError(f"object {r!r} is not renderable")
         except Exception:
             self.add_class("error")
             et, ev, tr = sys.exc_info()
@@ -44,7 +49,7 @@ class SlideWidget(SpielWidget):
                     traceback=tr,
                     suppress=(spiel,),
                 ),
-                title="Slide failed to render",
+                title="Slide content failed to render",
                 border_style=Style(bold=True, color="red1"),
                 box=HEAVY,
             )

spiel/widgets/widget.py

@@ -5,6 +5,8 @@ from typing import TYPE_CHECKING
 from textual.reactive import watch
 from textual.widget import Widget
 
+from spiel.slide import Slide
+
 if TYPE_CHECKING:
     from spiel.app import SpielApp
 
@@ -19,3 +21,7 @@ class SpielWidget(Widget):
 
     def r(self, _: object) -> None:
         self.refresh()
+
+    @property
+    def current_slide(self) -> Slide:
+        return self.app.deck[self.app.current_slide_idx]

tests/test_app.py

@@ -0,0 +1,51 @@
+from collections.abc import Iterable
+from itertools import combinations_with_replacement
+
+import pytest
+from hypothesis import given
+from hypothesis.strategies import lists, sampled_from
+
+import spiel.constants
+from spiel.app import SpielApp
+
+
+@pytest.fixture
+def app() -> SpielApp:
+    return SpielApp(deck_path=spiel.constants.DEMO_FILE)
+
+
+KEYS = [
+    "right",
+    "left",
+    "d",
+    "t",
+    "enter",
+    "up",
+    "down",
+    "escape",
+    "question_mark",
+]
+
+
+@pytest.mark.slow
+@given(keys=lists(elements=sampled_from(KEYS), max_size=100))
+async def test_hammer_on_the_keyboard_long_random(keys: Iterable[str]) -> None:
+    app = SpielApp(deck_path=spiel.constants.DEMO_FILE)
+    async with app.run_test() as pilot:
+        await pilot.press(*keys)
+
+
+@pytest.mark.slow
+@pytest.mark.parametrize("keys", combinations_with_replacement(KEYS, 3))
+async def test_hammer_on_the_keyboard_short_exhaustive(app: SpielApp, keys: Iterable[str]) -> None:
+    async with app.run_test() as pilot:
+        await pilot.press(*keys)
+
+
+async def test_advance_through_demo_slides(app: SpielApp) -> None:
+    async with app.run_test() as pilot:
+        keys = ("right",) * (len(app.deck) + 1)
+
+        await pilot.press(*keys)
+
+        assert app.current_slide_idx == len(app.deck) - 1

tests/test_slide_widget.py

@@ -0,0 +1,89 @@
+import pytest
+from pytest import FixtureRequest
+from pytest_mock import MockerFixture
+from rich.console import RenderableType
+from rich.panel import Panel
+from rich.text import Text
+
+from spiel import Slide
+from spiel.widgets.slide import SlideWidget
+
+
+@pytest.fixture(params=["", Text()])
+def slide(request: FixtureRequest) -> Slide:
+    def content() -> RenderableType:
+        return request.param
+
+    return Slide(content=content)
+
+
+@pytest.fixture
+def error_slide() -> Slide:
+    def content() -> RenderableType:
+        raise Exception()
+
+    return Slide(content=content)
+
+
+@pytest.fixture
+def unrenderable_slide() -> Slide:
+    def content() -> None:
+        return None
+
+    return Slide(content=content)  # type: ignore[arg-type]
+
+
+def mock(mocker: MockerFixture, slide: Slide) -> SlideWidget:
+    sw = SlideWidget()
+
+    mocker.patch.object(
+        type(sw),
+        "current_slide",
+        new_callable=mocker.PropertyMock,
+        return_value=slide,
+    )
+
+    assert sw.current_slide is slide
+
+    return sw
+
+
+def test_render(mocker: MockerFixture, slide: Slide) -> None:
+    sw = mock(mocker, slide)
+
+    assert sw.render() == slide.render(triggers=sw.triggers)
+
+    assert "error" not in sw.classes
+
+
+def test_render_raises_exception(mocker: MockerFixture, error_slide: Slide) -> None:
+    sw = mock(mocker, error_slide)
+
+    error = sw.render()
+
+    assert isinstance(error, Panel)
+    assert error.title == "Slide content failed to render"
+
+    assert "error" in sw.classes
+
+
+def test_render_content_not_renderable(mocker: MockerFixture, unrenderable_slide: Slide) -> None:
+    sw = mock(mocker, unrenderable_slide)
+
+    error = sw.render()
+
+    assert isinstance(error, Panel)
+    assert error.title == "Slide content failed to render"
+
+    assert "error" in sw.classes
+
+
+def test_update_triggers() -> None:
+    sw = SlideWidget()
+
+    initial_triggers = sw.triggers
+
+    sw.update_triggers()
+
+    assert initial_triggers.now <= sw.triggers.now
+    assert list(initial_triggers) == list(sw.triggers)