fix: make cairosvg optional and skip rasterizing

great_docs/core.py

@@ -718,9 +718,13 @@ def _generate_favicons(self, logo_src: Path, dest_dir: Path) -> dict[str, str]:
         """
         import io
 
-        import cairosvg
         from PIL import Image
 
+        try:
+            import cairosvg
+        except ImportError:
+            cairosvg = None  # type: ignore[assignment]
+
         result: dict[str, str] = {}
         suffix = logo_src.suffix.lower()
 
@@ -733,6 +737,16 @@ def _generate_favicons(self, logo_src: Path, dest_dir: Path) -> dict[str, str]:
             result["icon-svg"] = "favicon.svg"
             result["icon"] = "favicon.svg"
 
+            if cairosvg is None:
+                print(
+                    "Favicon: cairosvg is not installed; skipping raster favicon "
+                    "generation from SVG. Install it with:\n"
+                    "  pip install 'great-docs[svg]'\n"
+                    "On Linux you also need: apt install libcairo2-dev\n"
+                    "On macOS: brew install cairo"
+                )
+                return result
+
             # Rasterize SVG → PNG preserving aspect ratio, then resize
             png_data = cairosvg.svg2png(url=str(logo_src), scale=4)
             raw = Image.open(io.BytesIO(png_data))

pyproject.toml

@@ -39,11 +39,13 @@ dependencies = [
     "pygments>=2.0.0",
     "requests>=2.25.0",
     "Pillow>=9.0.0",
-    "cairosvg>=2.5.0",
     "ruff>=0.9.9",
 ]
 
 [project.optional-dependencies]
+svg = [
+    "cairosvg>=2.5.0",
+]
 dev = [
     "pytest>=6.0",
     "pytest-cov>=3.0",

tests/test_great_docs.py

@@ -9477,9 +9477,30 @@ def test_downscale_preserves_aspect_ratio(self):
         assert result.size == (100, 100)
 
 
+def _make_mock_cairosvg():
+    """Create a mock cairosvg module that returns valid PNG data from svg2png."""
+    import io as _io
+
+    mock_mod = types.ModuleType("cairosvg")
+
+    def svg2png(**kwargs):
+        img = PILImage.new("RGBA", (256, 256), (0, 0, 255, 255))
+        buf = _io.BytesIO()
+        img.save(buf, format="PNG")
+        return buf.getvalue()
+
+    mock_mod.svg2png = svg2png  # type: ignore[attr-defined]
+    return mock_mod
+
+
 class TestGenerateFaviconsSvg:
     """Tests for _generate_favicons with SVG source."""
 
+    @pytest.fixture(autouse=True)
+    def _mock_cairosvg(self):
+        with patch.dict("sys.modules", {"cairosvg": _make_mock_cairosvg()}):
+            yield
+
     def test_svg_generates_all_files(self):
         """SVG source should produce ico, svg, 16px, 32px, and apple-touch-icon."""
         with tempfile.TemporaryDirectory() as tmp_dir:
@@ -9725,6 +9746,11 @@ def test_favicon_invalid_type_returns_none(self):
 class TestFaviconLinkInjection:
     """Tests for favicon <link> tag injection into _quarto.yml."""
 
+    @pytest.fixture(autouse=True)
+    def _mock_cairosvg(self):
+        with patch.dict("sys.modules", {"cairosvg": _make_mock_cairosvg()}):
+            yield
+
     def _build_with_favicon(
         self, tmp_dir: str, favicon_config: str | None = None, create_logo: bool = False
     ) -> dict: