fix infinite loop

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Fixed progress speed not updating when total doesn't change
 - Fixed superfluous new line in Status https://github.com/willmcgugan/rich/issues/1662
+- Fixed infinite loop in set_cell_size https://github.com/willmcgugan/rich/issues/1682
 
 ## [10.13.0] - 2021-11-07
 

rich/cells.py

@@ -74,6 +74,8 @@ def _get_codepoint_cell_size(codepoint: int) -> int:
 
 def set_cell_size(text: str, total: int) -> str:
     """Set the length of a string to fit within given number of cells."""
+    if not total:
+        return ""
     cell_size = cell_len(text)
     if cell_size == total:
         return text
@@ -81,12 +83,12 @@ def set_cell_size(text: str, total: int) -> str:
         return text + " " * (total - cell_size)
 
     start = 0
-    end = cell_size
+    end = len(text)
 
     # Binary search until we find the right size
     while True:
         pos = (start + end) // 2
-        before = text[:pos]
+        before = text[: pos + 1]
         before_len = cell_len(before)
         if before_len == total + 1 and cell_len(before[-1]) == 2:
             return before[:-1] + " "

tests/test_cells.py

@@ -9,3 +9,15 @@ def test_set_cell_size():
     assert cells.set_cell_size("😽😽", 3) == "😽 "
     assert cells.set_cell_size("😽😽", 2) == "😽"
     assert cells.set_cell_size("😽😽", 1) == " "
+
+
+def test_set_cell_size_infinite():
+    for size in range(38):
+        assert (
+            cells.cell_len(
+                cells.set_cell_size(
+                    "เป็นเกมที่ต้องมีความอดทนมากที่สุดตั้งเเต่เคยเล่นมา", size
+                )
+            )
+            == size
+        )