Fix hang when Rule title greater than required space

rich/cells.py

@@ -80,7 +80,7 @@ def set_cell_size(text: str, total: int) -> str:
             return text + " " * (total - size)
         return text[:total]
 
-    if not total:
+    if total <= 0:
         return ""
     cell_size = cell_len(text)
     if cell_size == total:

rich/rule.py

@@ -63,10 +63,7 @@ class Rule(JupyterMixin):
 
         chars_len = cell_len(characters)
         if not self.title:
-            rule_text = Text(characters * ((width // chars_len) + 1), self.style)
-            rule_text.truncate(width)
-            rule_text.plain = set_cell_size(rule_text.plain, width)
-            yield rule_text
+            yield self._rule_line(chars_len, width)
             return
 
         if isinstance(self.title, Text):
@@ -76,10 +73,16 @@ class Rule(JupyterMixin):
 
         title_text.plain = title_text.plain.replace("\n", " ")
         title_text.expand_tabs()
-        rule_text = Text(end=self.end)
 
+        required_space = 4 if self.align == "center" else 2
+        truncate_width = max(0, width - required_space)
+        if not truncate_width:
+            yield self._rule_line(chars_len, width)
+            return
+
+        rule_text = Text(end=self.end)
         if self.align == "center":
-            title_text.truncate(width - 4, overflow="ellipsis")
+            title_text.truncate(truncate_width, overflow="ellipsis")
             side_width = (width - cell_len(title_text.plain)) // 2
             left = Text(characters * (side_width // chars_len + 1))
             left.truncate(side_width - 1)
@@ -90,12 +93,12 @@ class Rule(JupyterMixin):
             rule_text.append(title_text)
             rule_text.append(" " + right.plain, self.style)
         elif self.align == "left":
-            title_text.truncate(width - 2, overflow="ellipsis")
+            title_text.truncate(truncate_width, overflow="ellipsis")
             rule_text.append(title_text)
             rule_text.append(" ")
             rule_text.append(characters * (width - rule_text.cell_len), self.style)
         elif self.align == "right":
-            title_text.truncate(width - 2, overflow="ellipsis")
+            title_text.truncate(truncate_width, overflow="ellipsis")
             rule_text.append(characters * (width - title_text.cell_len - 1), self.style)
             rule_text.append(" ")
             rule_text.append(title_text)
@@ -103,6 +106,12 @@ class Rule(JupyterMixin):
         rule_text.plain = set_cell_size(rule_text.plain, width)
         yield rule_text
 
+    def _rule_line(self, chars_len: int, width: int) -> Text:
+        rule_text = Text(self.characters * ((width // chars_len) + 1), self.style)
+        rule_text.truncate(width)
+        rule_text.plain = set_cell_size(rule_text.plain, width)
+        return rule_text
+
     def __rich_measure__(
         self, console: Console, options: ConsoleOptions
     ) -> Measurement:
@@ -110,12 +119,16 @@ class Rule(JupyterMixin):
 
 
 if __name__ == "__main__":  # pragma: no cover
-    from rich.console import Console
     import sys
 
+    from rich.console import Console
+
     try:
         text = sys.argv[1]
     except IndexError:
         text = "Hello, World"
     console = Console()
     console.print(Rule(title=text))
+
+    console = Console()
+    console.print(Rule("foo"), width=4)

tests/test_rule.py

@@ -61,6 +61,47 @@ def test_rule_cjk():
     assert console.file.getvalue() == expected
 
 
+@pytest.mark.parametrize(
+    "align,outcome",
+    [
+        ("center", "───\n"),
+        ("left", "… ─\n"),
+        ("right", "─ …\n"),
+    ],
+)
+def test_rule_not_enough_space_for_title_text(align, outcome):
+    console = Console(width=3, file=io.StringIO(), record=True)
+    console.rule("Hello!", align=align)
+    assert console.file.getvalue() == outcome
+
+
+def test_rule_center_aligned_title_not_enough_space_for_rule():
+    console = Console(width=4, file=io.StringIO(), record=True)
+    console.rule("ABCD")
+    assert console.file.getvalue() == "────\n"
+
+
+@pytest.mark.parametrize("align", ["left", "right"])
+def test_rule_side_aligned_not_enough_space_for_rule(align):
+    console = Console(width=2, file=io.StringIO(), record=True)
+    console.rule("ABCD", align=align)
+    assert console.file.getvalue() == "──\n"
+
+
+@pytest.mark.parametrize(
+    "align,outcome",
+    [
+        ("center", "─ … ─\n"),
+        ("left", "AB… ─\n"),
+        ("right", "─ AB…\n"),
+    ],
+)
+def test_rule_just_enough_width_available_for_title(align, outcome):
+    console = Console(width=5, file=io.StringIO(), record=True)
+    console.rule("ABCD", align=align)
+    assert console.file.getvalue() == outcome
+
+
 def test_characters():
     console = Console(
         width=16,

tests/test_spinner.py

@@ -34,7 +34,6 @@ def test_spinner_render():
     assert result == expected
 
 
-@pytest.mark.skip(reason="Broken with Rule.__rich__measure in place")
 def test_spinner_update():
     time = 0.0
 
@@ -47,17 +46,15 @@ def test_spinner_update():
     spinner = Spinner("dots")
     console.print(spinner)
 
-    spinner.update(text="Bar", style="green", speed=2)
-    time += 80 / 1000
-    console.print(spinner)
+    rule = Rule("Bar")
 
-    spinner.update(text=Rule("Bar"))
+    spinner.update(text=rule)
     time += 80 / 1000
     console.print(spinner)
 
     result = console.end_capture()
     print(repr(result))
-    expected = f"⠋\n\x1b[32m⠙\x1b[0m Bar\n\x1b[32m⠸\x1b[0m \x1b[92m────── \x1b[0mBar\x1b[92m ───────\x1b[0m\n"
+    expected = "⠋\n⠙ \x1b[92m─\x1b[0m\n"
     assert result == expected