iio: test: add kunit tests for channel prefix naming generation

Add a KUnit test suite covering __iio_chan_prefix_emit(), the helper
that builds IIO sysfs attribute name prefixes from an iio_chan_spec.
The suite groups cases by the enum iio_shared_by mode it exercises:

  - IIO_SHARED_BY_ALL: produces an empty prefix.
  - IIO_SHARED_BY_DIR: emits direction only ("in" / "out").
  - IIO_SHARED_BY_TYPE: emits "<dir>_<type>" and the differential
    "<dir>_<type>-<type>" variant.
  - IIO_SEPARATE: covers the full matrix of indexed, differential,
    modified, output and extend_name combinations, plus the two
    documented error paths (differential without indexed, differential
    with modifier).

A final case exercises the seq_buf overflow path by passing an
undersized buffer and expects -EOVERFLOW.

Also, an entry is created under MAINTAINERS dedicated to tests for IIO
core helpers.

Signed-off-by: Rodrigo Alencar <rodrigo.alencar@analog.com>
Signed-off-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>

0 files changed, 0 insertions, 0 deletions