[css] Address "did you mean" PR feedback

src/textual/css/_help_text.py

@@ -149,7 +149,7 @@ def property_invalid_value_help_text(
         suggested_property_name = _contextualize_property_name(
             suggested_property_name, context
         )
-        bullets.append(Bullet(f"Did you mean [i]{suggested_property_name}[/]?"))
+        bullets.append(Bullet(f'Did you mean "{suggested_property_name}"?'))
     return HelpText(f"Invalid CSS property [i]{property_name}[/]", bullets=bullets)
 
 

src/textual/css/_styles_builder.py

@@ -1,8 +1,7 @@
 from __future__ import annotations
 
-from difflib import get_close_matches
 from functools import lru_cache
-from typing import cast, Iterable, NoReturn
+from typing import cast, Iterable, NoReturn, Sequence
 
 import rich.repr
 
@@ -47,6 +46,7 @@ from ..color import Color, ColorParseError
 from .._duration import _duration_as_seconds
 from .._easing import EASING
 from ..geometry import Spacing, SpacingDimensions, clamp
+from ..suggestions import get_suggestion
 
 
 def _join_tokens(tokens: Iterable[Token], joiner: str = "") -> str:
@@ -87,7 +87,7 @@ class StylesBuilder:
         process_method = getattr(self, f"process_{rule_name}", None)
 
         if process_method is None:
-            suggested_property_name = self._suggested_property_name_for_rule(
+            suggested_property_name = self._get_suggested_property_name_for_rule(
                 declaration.name
             )
             self.error(
@@ -115,12 +115,14 @@ class StylesBuilder:
             self.error(declaration.name, declaration.token, str(error))
 
     @lru_cache(maxsize=None)
-    def _processable_rule_names(self) -> frozenset[str]:
-        return frozenset(
-            [attr[8:] for attr in dir(self) if attr.startswith("process_")]
-        )
+    def _get_processable_rule_names(self) -> Sequence[str]:
+        """
+        Returns the list of CSS properties we can manage -
+        i.e. the ones for which we have a `process_[property name]` method
+        """
+        return [attr[8:] for attr in dir(self) if attr.startswith("process_")]
 
-    def _process_enum_multiple(
+    def _get_process_enum_multiple(
         self, name: str, tokens: list[Token], valid_values: set[str], count: int
     ) -> tuple[str, ...]:
         """Generic code to process a declaration with two enumerations, like overflow: auto auto"""
@@ -745,8 +747,10 @@ class StylesBuilder:
     process_content_align_horizontal = process_align_horizontal
     process_content_align_vertical = process_align_vertical
 
-    def _suggested_property_name_for_rule(self, rule_name: str) -> str | None:
-        possible_matches = get_close_matches(
-            rule_name, self._processable_rule_names(), n=1
-        )
-        return None if not possible_matches else possible_matches[0]
+    def _get_suggested_property_name_for_rule(self, rule_name: str) -> str | None:
+        """
+        Returns a valid CSS property "Python" name, or None if no close matches could be found.
+
+        Example: returns "background" for rule_name "bkgrund", "offset_x" for "ofset_x"
+        """
+        return get_suggestion(rule_name, self._get_processable_rule_names())

src/textual/suggestions.py

@@ -0,0 +1,24 @@
+from __future__ import annotations
+
+from difflib import get_close_matches
+from typing import Sequence
+
+
+def get_suggestion(word: str, possible_words: Sequence[str]) -> str | None:
+    """
+    Returns a close match of 'word' amongst 'possible_words', or None if no close matches could be found.
+
+    Example: returns "red" for word "redu" and possible words ("yellow", "red")
+    """
+    possible_matches = get_close_matches(word, possible_words, n=1)
+    return None if not possible_matches else possible_matches[0]
+
+
+def get_suggestions(word: str, possible_words: Sequence[str], count: int) -> list[str]:
+    """
+    Returns a list of up to 'count' matches of 'word' amongst 'possible_words' -
+    or an empty list if no close matches could be found.
+
+    Example: returns ["yellow", "ellow"] for word "yllow" and possible words ("yellow", "red", "ellow")
+    """
+    return get_close_matches(word, possible_words, n=count)

tests/css/test_stylesheet.py

@@ -64,6 +64,7 @@ def test_color_property_parsing(css_value, expectation, expected_color):
         ["backgroundu", "background"],
         ["bckgroundu", "background"],
         ["ofset-x", "offset-x"],
+        ["ofst_y", "offset-y"],
         ["colr", "color"],
         ["colour", "color"],
         ["wdth", "width"],
@@ -73,7 +74,7 @@ def test_color_property_parsing(css_value, expectation, expected_color):
     ],
 )
 def test_did_you_mean_for_css_property_names(
-    css_property_name, expected_property_name_suggestion
+    css_property_name: str, expected_property_name_suggestion
 ):
     stylesheet = Stylesheet()
     css = """
@@ -90,12 +91,15 @@ def test_did_you_mean_for_css_property_names(
         stylesheet.parse()
 
     _, help_text = err.value.errors.rules[0].errors[0]  # type: Any, HelpText
-    assert help_text.summary == f"Invalid CSS property [i]{css_property_name}[/]"
+    displayed_css_property_name = css_property_name.replace("_", "-")
+    assert (
+        help_text.summary == f"Invalid CSS property [i]{displayed_css_property_name}[/]"
+    )
 
     expected_bullets_length = 1 if expected_property_name_suggestion else 0
     assert len(help_text.bullets) == expected_bullets_length
     if expected_property_name_suggestion is not None:
         expected_suggestion_message = (
-            f"Did you mean [i]{expected_property_name_suggestion}[/]?"
+            f'Did you mean "{expected_property_name_suggestion}"?'
         )
         assert help_text.bullets[0].markup == expected_suggestion_message

tests/test_suggestions.py

@@ -0,0 +1,35 @@
+import pytest
+
+from textual.suggestions import get_suggestion, get_suggestions
+
+
+@pytest.mark.parametrize(
+    "word, possible_words, expected_result",
+    (
+        ["background", ("background",), "background"],
+        ["backgroundu", ("background",), "background"],
+        ["bkgrund", ("background",), "background"],
+        ["llow", ("background",), None],
+        ["llow", ("background", "yellow"), "yellow"],
+        ["yllow", ("background", "yellow", "ellow"), "yellow"],
+    ),
+)
+def test_get_suggestion(word, possible_words, expected_result):
+    assert get_suggestion(word, possible_words) == expected_result
+
+
+@pytest.mark.parametrize(
+    "word, possible_words, count, expected_result",
+    (
+        ["background", ("background",), 1, ["background"]],
+        ["backgroundu", ("background",), 1, ["background"]],
+        ["bkgrund", ("background",), 1, ["background"]],
+        ["llow", ("background",), 1, []],
+        ["llow", ("background", "yellow"), 1, ["yellow"]],
+        ["yllow", ("background", "yellow", "ellow"), 1, ["yellow"]],
+        ["yllow", ("background", "yellow", "ellow"), 2, ["yellow", "ellow"]],
+        ["yllow", ("background", "yellow", "red"), 2, ["yellow"]],
+    ),
+)
+def test_get_suggestions(word, possible_words, count, expected_result):
+    assert get_suggestions(word, possible_words, count) == expected_result