fix fold

Author: willmcgugan

src/textual/content.py

@@ -981,12 +981,12 @@ def fold(self, width: int) -> list[Content]:
             List of content instances.
         """
         if not self:
-            return []
+            return [self]
         text = self.plain
         lines: list[Content] = []
         position = 0
         width = max(width, 2)
-        while text:
+        while True:
             snip = text[position : position + width]
             if not snip:
                 break
@@ -998,7 +998,6 @@ def fold(self, width: int) -> list[Content]:
             if snip_cell_length == width:
                 # Cell length is exactly width
                 lines.append(self[position : position + width])
-                text = text[len(snip) :]
                 position += len(snip)
                 continue
             # TODO: Can this be more efficient?

tests/test_content.py

@@ -385,6 +385,25 @@ def test_wrap() -> None:
 @pytest.mark.parametrize(
     "content, width, expected",
     [
+        (
+            Content("111222333"),
+            3,
+            [
+                Content("111"),
+                Content("222"),
+                Content("333"),
+            ],
+        ),
+        (
+            Content("1112223334"),
+            3,
+            [
+                Content("111"),
+                Content("222"),
+                Content("333"),
+                Content("4"),
+            ],
+        ),
         (
             Content(""),
             10,
@@ -445,16 +464,16 @@ def test_wrap() -> None:
             [
                 Content("💩H"),
                 Content.from_markup("[b]ell"),
-                Content.from_markup("[b]o[/]"),
+                Content.from_markup("o"),
             ],
         ),
         (
-            Content.from_markup("💩H[b]ell[/]💩"),
+            Content.from_markup("💩H[b]ell[/]o💩"),
             3,
             [
                 Content("💩H"),
                 Content.from_markup("[b]ell"),
-                Content.from_markup("[b]o[/]💩"),
+                Content.from_markup("o💩"),
             ],
         ),
         (
@@ -548,5 +567,6 @@ def test_fold(content: Content, width: int, expected: list[Content]) -> None:
     """
     result = content.fold(width)
     assert isinstance(result, list)
+    assert len(result) == len(expected)
     for line, expected_line in zip(result, expected):
         assert line.is_same(expected_line)