test: turn unexpected warnings into errors (#2480)

Author: schloerke

pytest.ini

@@ -5,4 +5,17 @@ asyncio_default_fixture_loop_scope=function
 testpaths=tests/pytest/
 ; Note: Browsers are set within `./Makefile`
 addopts = --strict-markers --durations=6 --durations-min=5.0 --numprocesses auto
+; Tests must not emit stray warnings; assert expected ones with `pytest.warns()`.
+; Third-party deprecations we can't act on go in the ignore list below.
+filterwarnings =
+    error
+    ; narwhals calls polars' deprecated `cat.get_categories()`
+    ; https://github.com/narwhals-dev/narwhals/issues/3895
+    ignore:`cat.get_categories\(\)` is deprecated:DeprecationWarning
+    ; Both of these are raised from finalizers at GC time (a leaked
+    ; `TemporaryDirectory`, an abandoned coroutine), so as errors they fail
+    ; whichever test happens to be running when the collector fires rather than the
+    ; test at fault -- i.e. they make the suite flaky instead of strict.
+    ignore::ResourceWarning
+    ignore::pytest.PytestUnraisableExceptionWarning
 ; verbosity_test_cases=2

tests/pytest/test_offcanvas.py

@@ -317,9 +317,11 @@ def test_show_offcanvas_with_html_wraps_new_panel():
     """show_offcanvas() treats htmltools.HTML() as content, not an id"""
     mock_session = _mock_session()
 
-    result_id = ui.show_offcanvas(
-        HTML("<p>Rendered content.</p>"), session=mock_session
-    )
+    # An anonymous panel has no title, so it also warns about accessibility.
+    with pytest.warns(UserWarning, match="aria-label"):
+        result_id = ui.show_offcanvas(
+            HTML("<p>Rendered content.</p>"), session=mock_session
+        )
 
     assert isinstance(result_id, str) and result_id != ""
     assert mock_session._send_message_sync.call_count == 1
@@ -333,7 +335,9 @@ def test_show_offcanvas_with_tag_wraps_new_panel():
     """show_offcanvas() wraps a bare Tag into a new anonymous offcanvas"""
     mock_session = _mock_session()
 
-    result_id = ui.show_offcanvas(tags.p("Body content"), session=mock_session)
+    # An anonymous panel has no title, so it also warns about accessibility.
+    with pytest.warns(UserWarning, match="aria-label"):
+        result_id = ui.show_offcanvas(tags.p("Body content"), session=mock_session)
 
     assert mock_session._send_message_sync.call_count == 1
     message = mock_session._messages_sent[0]

tests/pytest/test_renderer.py

@@ -109,21 +109,21 @@ def bad_render(x: int) -> str:
 def test_download_rejects_function_with_params():
     with pytest.raises(TypeError, match="no required parameters"):
 
-        @render.download  # pyright: ignore[reportArgumentType]
+        @render.download_button  # pyright: ignore[reportArgumentType]
         def bad_download(x: int) -> str:
             return str(x)
 
 
 def test_download_accepts_function_with_no_params():
-    @render.download
+    @render.download_button
     def good_download():
         return "file.txt"
 
 
 def test_download_warns_function_with_default_params():
     with pytest.warns(UserWarning, match="parameter.*with default values: x"):
 
-        @render.download
+        @render.download_button
         def good_download(x: str = "file.txt") -> str:
             return x