# Description - fixes#14174
This PR addresses a bug in the `seq char` command where the command's
behavior did not align with its help description, which stated that it
prints a sequence of ASCII characters. The initial implementation only
allowed alphabetic characters, leading to user confusion when
non-alphabetic characters (e.g., digits, punctuation) were rejected or
when unexpected behavior occurred for certain input ranges.
### Changes Made:
- **Updated the input validation**: Modified the `is_single_character`
function to accept any ASCII character instead of restricting to
alphabetic characters.
- **Enhanced error messages**: Clarified error messages to specify that
any single ASCII character is acceptable.
- **Expanded functionality**: Ensured that the command can now generate
sequences that include non-alphabetic ASCII characters.
- **Updated tests**: Added tests to cover new use cases involving
non-alphabetic characters and improved validation.
### Examples After Fix:
- `seq char '0' '9'` now outputs `['0', '1', '2', '3', '4', '5', '6',
'7', '8', '9']`
- `seq char ' ' '/'` outputs a list of characters from space to `/`
- `seq char 'A' 'z'` correctly includes alphabetic and non-alphabetic
characters between `A` and `z`
# User-Facing Changes
- Users can now input any single ASCII character for the `start` and
`end` parameters of `seq char`.
- The output will accurately include all characters within the specified
ASCII range, including digits and punctuation.
# Tests + Formatting
- Added new tests to ensure the `seq char` command supports sequences
including non-alphabetic ASCII characters.
This PR just tidies up some tests by removing unused code:
1. If the filesystem is not touched, don't use the filesystem
playground/sandbox
2. If the filesystem is not touched, don't specify the `cwd`
3. If the command is short, don't bother wrapping it in `pipeline()`
4. If the command doesn't have quotes, don't bother with a `r#"..."#`
raw string
Part of #8670.
