Clarify test-completion doc string

* src/minibuf.c (Ftest_completion): Clarify what it means to be a
valid completion (bug#50583).

diff --git a/src/minibuf.c b/src/minibuf.c
index c9134eff67fe312325b83da918c4682cde0c1ac1..a0ba86763f444a36bf08e350e7650345daa860c1 100644 (file)
--- a/src/minibuf.c
+++ b/src/minibuf.c
@@ -2055,7 +2055,11 @@ See also `completing-read-function'.  */)
 /* Test whether TXT is an exact completion.  */
 DEFUN ("test-completion", Ftest_completion, Stest_completion, 2, 3, 0,
        doc: /* Return non-nil if STRING is a valid completion.
+For instance, if COLLECTION is a list of strings, this is true if
+STRING appears in the list and PREDICATE is satisfied.
+
 Takes the same arguments as `all-completions' and `try-completion'.
+
 If COLLECTION is a function, it is called with three arguments:
 the values STRING, PREDICATE and `lambda'.  */)
   (Lisp_Object string, Lisp_Object collection, Lisp_Object predicate)