👌 IMPROVE: Use Sphinx HTML assets policy to decide whether include as…

…sets

Sphinx v4.1.0 will include `Sphinx.registry.html_assets_policy` that defines the
policy to whether include or not HTML assets in pages where the extension is not
used.

This PR makes usage of this policy to decide if sphinx-tabs assets should be
included or not in the page that's being rendered.

Reference: sphinx-doc/sphinx#9115

sphinx_tabs/tabs.py

@@ -1,6 +1,7 @@
 """ Tabbed views for Sphinx, with HTML builder """
 
 import base64
+import sphinx
 from pathlib import Path
 from functools import partial
 
@@ -313,7 +314,12 @@ def update_context(app, pagename, templatename, context, doctree):
         return
     visitor = _FindTabsDirectiveVisitor(doctree)
     doctree.walk(visitor)
-    if not visitor.found_tabs_directive:
+
+    include_assets_in_all_pages = False
+    if sphinx.version_info >= (4, 1, 0):
+        include_assets_in_all_pages = app.registry.html_assets_policy == 'always'
+
+    if not visitor.found_tabs_directive and not include_assets_in_all_pages:
         paths = [Path("_static") / f for f in FILES]
         if "css_files" in context:
             context["css_files"] = context["css_files"][:]

tests/test_build.py

@@ -25,6 +25,15 @@ def test_conditional_assets(app, docname, check_asset_links):
         )
 
 
+@pytest.mark.parametrize("docname", ["index", "no_tabs1", "no_tabs2"])
+@pytest.mark.sphinx(testroot="conditionalassets")
+@pytest.mark.skipif(
+    sphinx.version_info[:2] >= (4, 1), reason="Test uses Sphinx 4.1 config"
+)
+def test_conditional_assets(app, docname, check_asset_links):
+    check_asset_links(app, filename=docname + ".html")
+
+
 @pytest.mark.sphinx(testroot="linenos")
 @pytest.mark.skipif(
     sphinx.version_info[:2] >= (4, 0), reason="Test uses Sphinx 3 code blocks"