Update tests.

tests/css/test_text_style.py

@@ -1,20 +0,0 @@
-from rich.style import Style
-
-from textual.css.styles import Styles
-
-
-def test_text_style_none():
-    styles = Styles()
-    styles.text_style = "none"
-    assert styles.text_style == Style()
-
-
-def test_text_style_none_with_others():
-    """Style "none" mixed with others should result in empty style."""
-    styles = Styles()
-    styles.text_style = "bold none underline italic"
-
-    none_styles = Styles()
-    styles.text_style = "none"
-
-    assert styles.text_style == none_styles.text_style

tests/test_style_properties.py

@@ -1,4 +1,8 @@
+import pytest
+from rich.style import Style
+
 from textual.color import Color
+from textual.css.errors import StyleValueError
 from textual.css.styles import Styles
 
 
@@ -7,3 +11,12 @@ def test_box_normalization():
     styles = Styles()
     styles.border_left = ("none", "red")
     assert styles.border_left == ("", Color.parse("red"))
+
+
+@pytest.mark.parametrize("style_attr", ["text_style", "link_style"])
+def test_text_style_none_with_others(style_attr):
+    """Style "none" mixed with others should give custom Textual exception."""
+    styles = Styles()
+
+    with pytest.raises(StyleValueError) as exc_info:
+        setattr(styles, style_attr, "bold none underline italic")