master 3806d21 1/2: Fix small bug in 'completion-table-subvert'.

[Philipp Stephani]

branch: master
commit 3806d2168bdc36796d2dfac5f743582f0ce71c72
Author: Philipp Stephani <phst@google.com>
Commit: Philipp Stephani <phst@google.com>

    Fix small bug in 'completion-table-subvert'.
    
    Even for a trivial underlying completion table (where the 'boundaries'
    action returns nil), we need to provide nontrivial boundaries so that
    they match the behavior of 'all-completions'.
    
    * lisp/minibuffer.el (completion-table-subvert): Return boundaries
    even for trivial underlying completion table.
    * test/lisp/minibuffer-tests.el (completion-table-subvert-test):
    Amend unit test to also test boundaries.  While there, also test
    the other completion functions.
---
 lisp/minibuffer.el            | 2 +-
 test/lisp/minibuffer-tests.el | 7 ++++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/lisp/minibuffer.el b/lisp/minibuffer.el
index 7da3c39..51e0519 100644
--- a/lisp/minibuffer.el
+++ b/lisp/minibuffer.el
@@ -271,7 +271,7 @@ the form (concat S2 S)."
     (let* ((str (if (string-prefix-p s1 string completion-ignore-case)
                     (concat s2 (substring string (length s1)))))
            (res (if str (complete-with-action action table str pred))))
-      (when res
+      (when (or res (eq (car-safe action) 'boundaries))
         (cond
          ((eq (car-safe action) 'boundaries)
           (let ((beg (or (and (eq (car-safe res) 'boundaries) (cadr res)) 0)))
diff --git a/test/lisp/minibuffer-tests.el b/test/lisp/minibuffer-tests.el
index 791e51c..027711c 100644
--- a/test/lisp/minibuffer-tests.el
+++ b/test/lisp/minibuffer-tests.el
@@ -83,7 +83,12 @@
   (let* ((origtable '("A-hello" "A-there"))
          (subvtable (completion-table-subvert origtable "B" "A")))
     (should (equal (try-completion "B-hel" subvtable)
-                   "B-hello"))))
+                   "B-hello"))
+    (should (equal (all-completions "B-hel" subvtable) '("-hello")))
+    (should (test-completion "B-hello" subvtable))
+    (should (equal (completion-boundaries "B-hel" subvtable
+                                          nil "suffix")
+                   '(1 . 6)))))
 
 (ert-deftest completion-table-test-quoting ()
   (let ((process-environment