Fix for resolve_fraction_unit zero division error (#2502)

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
+## Unreleased
+
+### Fixed
+
+- Fixed `ZeroDivisionError` in `resolve_fraction_unit` https://github.com/Textualize/textual/issues/2502
+
 ## [0.24.1] - 2023-05-08
 
 ### Fixed

src/textual/_resolve.py

@@ -143,7 +143,7 @@ def resolve_scalar(
     resolved: list[Fraction | None] = [None] * len(resolve)
     remaining_fraction = Fraction(sum(scalar.value for scalar, _, _ in resolve))
 
-    while True:
+    while remaining_fraction > 0:
         remaining_space_changed = False
         resolve_fraction = Fraction(remaining_space, remaining_fraction)
         for index, (scalar, min_value, max_value) in enumerate(resolve):
@@ -166,7 +166,7 @@ def resolve_scalar(
 
     return (
         Fraction(remaining_space, remaining_fraction)
-        if remaining_space
+        if remaining_space > 0
         else Fraction(1)
     )
 

tests/test_resolve.py

@@ -1,4 +1,5 @@
 from fractions import Fraction
+from itertools import chain
 
 import pytest
 
@@ -122,3 +123,22 @@ def test_resolve_fraction_unit():
         Fraction(32),
         resolve_dimension="width",
     ) == Fraction(2)
+
+
+def test_resolve_issue_2502():
+    """Test https://github.com/Textualize/textual/issues/2502"""
+
+    widget = Widget()
+    widget.styles.width = "1fr"
+    widget.styles.min_width = 11
+
+    assert isinstance(
+        resolve_fraction_unit(
+            (widget.styles,),
+            Size(80, 24),
+            Size(80, 24),
+            Fraction(10),
+            resolve_dimension="width",
+        ),
+        Fraction,
+    )