Merge patch series "add [ as alias for test, fix 0/1 argument handling"

Rasmus Villemoes <ravi@prevas.dk> says:

Make 'test' behave a little more like its cousins in other shells, by
allowing the [ ... ] spelling, and while here, fix up the handling of
a single, non-empty argument to comply with POSIX.

Link: https://lore.kernel.org/r/20260312100106.702368-1-ravi@prevas.dk

doc/usage/cmd/test.rst

@@ -20,11 +20,14 @@ Synopsis
     test -e <interface> <dev[:part]> <path>
     test <s> =~ <re>
 
+    [ <test expression> ]
+
 Description
 -----------
 
 The ``test`` command is similar to the ordinary shell built-in by the
-same name. Unlike in ordinary shells, it cannot be spelled ``[``.
+same name. Like in ordinary shells, it can also be spelled ``[``,
+provided the test expression is followed by a separate ``]`` argument.
 
 Strings
 ~~~~~~~