fix(lftest): accept --test args with fewer than three elements

The `test()` helper previously required callers to pass a three-element
CSV (`stdout,stderr,retc`). Plugins that only need to inject STDOUT had
to trail `,,0` on every invocation, and typing `--test=path/to/fixture`
from the command line tripped an `IndexError` on `args[1]`.

Fall back to `''` for stderr and `0` for retc when those positions are
absent, so both `--test=stdout/foo` and `--test=stdout/foo,,0` work
interchangeably.

Author: markuslf

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Changed
 
 * base.py: `get_worst()` now accepts any number of state arguments (`*states`). Existing two-argument callers keep working unchanged, but plugins that need to combine three or more states in one call no longer have to nest the call - e.g. `get_worst(state, used_state, committed_state)` instead of `get_worst(state, get_worst(used_state, committed_state))`
+* lftest.py: `test()` now accepts `args` with fewer than three elements. Plugins can be invoked as `--test=path/to/fixture` without the trailing `,,0`; stderr defaults to the empty string and the return code to `0`
 
 ### Fixed
 

lftest.py

@@ -16,7 +16,7 @@
 from . import base, disk, shell
 
 __author__ = 'Linuxfabrik GmbH, Zurich/Switzerland'
-__version__ = '2026041201'
+__version__ = '2026041301'
 
 
 def run(test_instance, plugin, testcase):
@@ -192,11 +192,16 @@ def test(args):
     Returns the content of two files and the provided return code. The first file represents STDOUT,
     and the second represents STDERR. This function is useful for enabling unit tests.
 
+    Only the STDOUT entry is required. STDERR and the return code default to
+    the empty string and 0, so callers can pass `--test=path/to/stdout`
+    without trailing commas.
+
     ### Parameters
     - **args** (`list`): A list containing:
       - The path to the file representing STDOUT or the string to be used as STDOUT.
-      - The path to the file representing STDERR or the string to be used as STDERR.
-      - The return code (integer or string). Defaults to 0 if not provided.
+      - Optional: the path to the file representing STDERR or the string to be used
+        as STDERR. Defaults to the empty string if not provided.
+      - Optional: the return code (integer or string). Defaults to 0 if not provided.
 
     ### Returns
     - **tuple**:
@@ -205,11 +210,13 @@ def test(args):
       - **retc** (`int`): The return code, either from the provided value or defaulted to 0.
 
     ### Example
-    >>> test('path/to/stdout.txt', 'path/to/stderr.txt', 128)
+    >>> test(['path/to/stdout.txt', 'path/to/stderr.txt', 128])
     ('This is stdout content', 'This is stderr content', 128)
+    >>> test(['path/to/stdout.txt'])
+    ('This is stdout content', '', 0)
     """
-    stdout = args[0]
-    stderr = args[1]
+    stdout = args[0] if len(args) > 0 else ''
+    stderr = args[1] if len(args) > 1 else ''
     retc = int(args[2]) if len(args) > 2 and args[2] != '' else 0
 
     if stdout and os.path.isfile(stdout):