Fix codeblock dynamic line length calculation for indented examples

[MichaReiser]

Summary

This PR fixes the line-length calculation for the mode dynamic for docstring code blocks.

def length(numbers: list[int]) -> int:
    """Get the length of the given list of numbers.

    Example:
        >>> length([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20])
        20
    """
    return len(numbers)

The current implementation only accounted for the docstring's indent and the space taken by the >>> but it didn't account for the indent inside the docstring (for spaces relative to Example). This PR changes the line length calculation to consider the relative indent.

Fixes #13358

Test Plan

I added a few new tests that and they demonstrate that the lines remain collapsed but expand in preview mode (with the fix).

I reviewed all ecosystem changes and they look correct. Many of those docstrings also have E501 suppressions that won't be needed with the fix.

[github-actions]

ruff-ecosystem results

Formatter (stable)

✅ ecosystem check detected no format changes.

Formatter (preview)

ℹ️ ecosystem check detected format changes. (+20 -6 lines in 4 files in 3 projects; 51 projects unchanged)

apache/airflow (+3 -1 lines across 1 file)

ruff format --preview

airflow/models/baseoperator.py~L1264

             # This is equivalent to
             with DAG(...):
                 generate_content = GenerateContentOperator(task_id="generate_content")
-                send_email = EmailOperator(..., html_content="{{ task_instance.xcom_pull('generate_content') }}")
+                send_email = EmailOperator(
+                    ..., html_content="{{ task_instance.xcom_pull('generate_content') }}"
+                )
                 generate_content >> send_email
 
         """

pandas-dev/pandas (+14 -4 lines across 2 files)

ruff format --preview

pandas/core/arrays/base.py~L1793

                # type for the array, to the physical storage type for
                # the data, before passing to take.
 
-               result = take(data, indices, fill_value=fill_value, allow_fill=allow_fill)
+               result = take(
+                   data, indices, fill_value=fill_value, allow_fill=allow_fill
+               )
                return self._from_sequence(result, dtype=self.dtype)
         """  # noqa: E501
         # Implementer note: The `fill_value` parameter should be a user-facing

pandas/plotting/_core.py~L247

     .. plot::
         :context: close-figs
 
-        >>> data = {"length": [1.5, 0.5, 1.2, 0.9, 3], "width": [0.7, 0.2, 0.15, 0.2, 1.1]}
+        >>> data = {
+        ...     "length": [1.5, 0.5, 1.2, 0.9, 3],
+        ...     "width": [0.7, 0.2, 0.15, 0.2, 1.1],
+        ... }
         >>> index = ["pig", "rabbit", "duck", "chicken", "horse"]
         >>> df = pd.DataFrame(data, index=index)
         >>> hist = df.hist(bins=3)

pandas/plotting/_core.py~L833

         :context: close-figs
 
         >>> df = pd.DataFrame(
-        ...     {"length": [1.5, 0.5, 1.2, 0.9, 3], "width": [0.7, 0.2, 0.15, 0.2, 1.1]},
+        ...     {
+        ...         "length": [1.5, 0.5, 1.2, 0.9, 3],
+        ...         "width": [0.7, 0.2, 0.15, 0.2, 1.1],
+        ...     },
         ...     index=["pig", "rabbit", "duck", "chicken", "horse"],
         ... )
         >>> plot = df.plot(title="DataFrame Plot")

pandas/plotting/_core.py~L1614

             ...         "signups": [5, 5, 6, 12, 14, 13],
             ...         "visits": [20, 42, 28, 62, 81, 50],
             ...     },
-            ...     index=pd.date_range(start="2018/01/01", end="2018/07/01", freq="ME"),
+            ...     index=pd.date_range(
+            ...         start="2018/01/01", end="2018/07/01", freq="ME"
+            ...     ),
             ... )
             >>> ax = df.plot.area()
 

pytest-dev/pytest (+3 -1 lines across 1 file)

ruff format --preview

src/_pytest/python_api.py~L858

 
        Given that ``pytest.raises`` matches subclasses, be wary of using it to match :class:`Exception` like this::
 
-           with pytest.raises(Exception):  # Careful, this will catch ANY exception raised.
+           with pytest.raises(
+               Exception
+           ):  # Careful, this will catch ANY exception raised.
                some_function()
 
        Because :class:`Exception` is the base class of almost all exceptions, it is easy for this to hide

[BurntSushi]

How come this is treated as a new style instead of a bug fix? (Sorry, I'm probably out of step with what our policy is here.)

[MichaReiser]

The formatter versioning policy is rather strict:

The stable style changed to prevent invalid syntax, changes to the program's semantics, or removal of comments

It only allows hard correctness errors. The only other permitted changes are bug fixes that don't change any already formatted code. For example, we can fix a bug where the formatter incorrectly collapses two blank lines to one instead of preserving one or two.

The motivation for this strict rule is that a ruff format --check command shouldn't start failing between patch versions for already formatted code.