Simplify erc-button movement commands

* etc/ERC-NEWS: Mention TAB being bound to new command `erc-tab' and
`erc-previous-button' now stopping at the start of buttons.
* lisp/erc/erc-button.el (erc-button-mode, erc-button-enable,
erc-button-disable): Add and remove `erc-button-next' to
`erc--tab-functions' hook, which is tantamount to binding the command
in the read-only area of an ERC buffer.
(erc-button-next-function): Deprecate and remove from client code path
because this module doesn't concern itself with prompt input and thus
no longer needs to conform to the `completion-at-point-functions'
interface.
(erc-button--prev-next-predicate-functions): New variable, a hook to
determine whether to continue searching for a button.  Other modules
should utilize this as needed.
(erc-button--end-of-button-p): Add function to serve as default value
for `erc-button--continue-predicate'.
(erc--button-next): Add generalized button-movement function.
(erc-button-next, erc-button-previous): Make `erc-button-previous'
behave more predictably by having it land at the beginning of buttons.
And remove roundabout appeal to HOF in `erc-button-next'.
(erc-button-previous-of-nick): New command to jump to previous
appearance of nick at point.
* lisp/erc/erc-fill.el (erc-fill-wrap, erc-fill-wrap-enable,
erc-fill-wrap-disable): Add and remove merge-related hookee from
`erc-button--prev-next-predicate-functions'.
(erc-fill--wrap-merged-button-p): New function to detect redundant
speakers.
* lisp/erc/erc.el (erc-complete-functions): Quote TAB in doc string.
(erc-mode-map): Bind `erc-tab' to TAB.
(erc--tab-functions, erc-tab): Add new command and hook to serve as
unified dispatch for TAB-related operations.  It calls `c-a-p' in the
input area and defers to module code in the read-only message area.
* test/lisp/erc/erc-button-tests.el: New file.
* test/lisp/erc/erc-fill-tests.el (erc-fill-tests--wrap-populate): Run
finalizer for transient keymap timer.
* test/lisp/erc/erc-tests.el
(erc-button--display-error-notice-with-keys): Move to new dedicated
test file for erc-button and fix expected behavior of
`erc-button-previous'.  (Bug#62834)

3 files changed, 179 insertions, 61 deletions

diff --git a/test/lisp/erc/erc-button-tests.el b/test/lisp/erc/erc-button-tests.el
new file mode 100644
index 00000000000..ced08d117bc
--- /dev/null
+++ b/test/lisp/erc/erc-button-tests.el
@@ -0,0 +1,177 @@
+;;; erc-button-tests.el --- Tests for erc-button  -*- lexical-binding:t -*-
+
+;; Copyright (C) 2023 Free Software Foundation, Inc.
+
+;; This file is part of GNU Emacs.
+;;
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published
+;; by the Free Software Foundation, either version 3 of the License,
+;; or (at your option) any later version.
+;;
+;; GNU Emacs is distributed in the hope that it will be useful, but
+;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;; General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;;; Code:
+
+(require 'erc-button)
+
+(defun erc-button-tests--insert-privmsg (speaker &rest msg-parts)
+  (declare (indent 1))
+  (let ((msg (erc-format-privmessage speaker
+                                     (apply #'concat msg-parts) nil t)))
+    (erc-display-message nil nil (current-buffer) msg)))
+
+(defun erc-button-tests--populate (test)
+  (let ((inhibit-message noninteractive)
+        erc-kill-channel-hook erc-kill-server-hook erc-kill-buffer-hook)
+
+    (with-current-buffer
+        (cl-letf
+            (((symbol-function 'erc-server-connect)
+              (lambda (&rest _)
+                (setq erc-server-process
+                      (start-process "sleep" (current-buffer) "sleep" "1"))
+                (set-process-query-on-exit-flag erc-server-process nil))))
+
+          (erc-open "localhost" 6667 "tester" "Tester" 'connect
+                    nil nil nil nil nil "tester" 'foonet))
+
+      (with-current-buffer (erc--open-target "#chan")
+        (erc-update-channel-member
+         "#chan" "alice" "alice" t nil nil nil nil nil "fake" "~u" nil nil t)
+
+        (erc-update-channel-member
+         "#chan" "bob" "bob" t nil nil nil nil nil "fake" "~u" nil nil t)
+
+        (erc-display-message
+         nil 'notice (current-buffer)
+         (concat "This server is in debug mode and is logging all user I/O. "
+                 "Blah alice (1) bob (2) blah."))
+
+        (funcall test))
+
+      (when noninteractive
+        (kill-buffer "#chan")
+        (kill-buffer)))))
+
+(ert-deftest erc-button-next ()
+  (erc-button-tests--populate
+   (lambda ()
+     (erc-button-tests--insert-privmsg "alice"
+       "(3) bob (4) come, you are a tedious fool: to the purpose.")
+
+     (erc-button-tests--insert-privmsg "bob"
+       "(5) alice (6) Come me to what was done to her.")
+
+     (should (= erc-input-marker (point)))
+
+     ;; Break out of input area
+     (erc-button-previous 1)
+     (should (looking-at (rx "alice (6)")))
+
+     ;; No next button
+     (should-error (erc-button-next 1) :type 'user-error)
+     (should (looking-at (rx "alice (6)")))
+
+     ;; Next with negative arg is equivalent to previous
+     (erc-button-next -1)
+     (should (looking-at (rx "bob> (5)")))
+
+     ;; One past end of button
+     (forward-char 3)
+     (should (looking-at (rx "> (5)")))
+     (should-not (get-text-property (point) 'erc-callback))
+     (erc-button-previous 1)
+     (should (looking-at (rx "bob> (5)")))
+
+     ;; At end of button
+     (forward-char 2)
+     (should (looking-at (rx "b> (5)")))
+     (erc-button-previous 1)
+     (should (looking-at (rx "bob (4)")))
+
+     ;; Skip multiple buttons back
+     (erc-button-previous 2)
+     (should (looking-at (rx "bob (2)")))
+
+     ;; Skip multiple buttons forward
+     (erc-button-next 2)
+     (should (looking-at (rx "bob (4)")))
+
+     ;; No error as long as some progress made
+     (erc-button-previous 100)
+     (should (looking-at (rx "alice (1)")))
+
+     ;; Error when no progress made
+     (should-error (erc-button-previous 1) :type 'user-error)
+     (should (looking-at (rx "alice (1)"))))))
+
+;; See also `erc-scenarios-networks-announced-missing' in
+;; erc-scenarios-misc.el for a more realistic example.
+(ert-deftest erc-button--display-error-notice-with-keys ()
+  (with-current-buffer (get-buffer-create "*fake*")
+    (let ((mode erc-button-mode)
+          (inhibit-message noninteractive)
+          erc-modules
+          erc-kill-channel-hook erc-kill-server-hook erc-kill-buffer-hook)
+      (erc-mode)
+      (setq erc-server-process
+            (start-process "sleep" (current-buffer) "sleep" "1"))
+      (set-process-query-on-exit-flag erc-server-process nil)
+      (erc--initialize-markers (point) nil)
+      (erc-button-mode +1)
+      (should (equal (erc-button--display-error-notice-with-keys
+                      "If \\[erc-bol] fails, "
+                      "see \\[erc-bug] or `erc-mode-map'.")
+                     "*** If C-a fails, see M-x erc-bug or `erc-mode-map'."))
+      (goto-char (point-min))
+
+      (ert-info ("Keymap substitution succeeds")
+        (erc-button-next 1)
+        (should (looking-at "C-a"))
+        (should (eq (get-text-property (point) 'mouse-face) 'highlight))
+        (erc-button-press-button)
+        (with-current-buffer "*Help*"
+          (goto-char (point-min))
+          (should (search-forward "erc-bol" nil t)))
+        (erc-button-next 1)
+        ;; End of interval correct
+        (erc-button-previous 1)
+        (should (looking-at "C-a fails")))
+
+      (ert-info ("Extended command mapping succeeds")
+        (erc-button-next 1)
+        (should (looking-at "M-x erc-bug"))
+        (erc-button-press-button)
+        (should (eq (get-text-property (point) 'mouse-face) 'highlight))
+        (with-current-buffer "*Help*"
+          (goto-char (point-min))
+          (should (search-forward "erc-bug" nil t))))
+
+      (ert-info ("Symbol-description face preserved") ; mutated by d-e-n-w-k
+        (erc-button-next 1)
+        (should (equal (get-text-property (point) 'font-lock-face)
+                       '(erc-button erc-error-face)))
+        (should (eq (get-text-property (point) 'mouse-face) 'highlight))
+        (should (eq erc-button-face 'erc-button))) ; extent evaporates
+
+      (ert-info ("Format when trailing args include non-strings")
+        (should (equal (erc-button--display-error-notice-with-keys
+                        "abc" " %d def" " 45%s" 123 '\6)
+                       "*** abc 123 def 456")))
+
+      (when noninteractive
+        (unless mode
+          (erc-button-mode -1))
+        (kill-buffer "*Help*")
+        (kill-buffer)))))
+
+;;; erc-button-tests.el ends here
diff --git a/test/lisp/erc/erc-fill-tests.el b/test/lisp/erc/erc-fill-tests.el
index e8dd25e8ea1..170436ffbaa 100644
--- a/test/lisp/erc/erc-fill-tests.el
+++ b/test/lisp/erc/erc-fill-tests.el
@@ -94,6 +94,8 @@
           ;; Defend against non-local exits from `ert-skip'
           (unwind-protect
               (funcall test)
+            (when set-transient-map-timer
+              (timer-event-handler set-transient-map-timer))
             (set-window-buffer (selected-window) original-window-buffer)
             (when noninteractive
               (while-let ((buf (pop erc-fill-tests--buffers)))
diff --git a/test/lisp/erc/erc-tests.el b/test/lisp/erc/erc-tests.el
index 88b9babf206..5aaf7e499e3 100644
--- a/test/lisp/erc/erc-tests.el
+++ b/test/lisp/erc/erc-tests.el
@@ -2110,65 +2110,4 @@ connection."
                       (put 'erc-mname-enable 'definition-name 'mname)
                       (put 'erc-mname-disable 'definition-name 'mname))))))
 
-
-;; XXX move erc-button tests to new file if more added.
-(require 'erc-button)
-
-;; See also `erc-scenarios-networks-announced-missing' in
-;; erc-scenarios-misc.el for a more realistic example.
-(ert-deftest erc-button--display-error-notice-with-keys ()
-  (with-current-buffer (get-buffer-create "*fake*")
-    (let ((mode erc-button-mode)
-          (inhibit-message noninteractive)
-          erc-modules
-          erc-kill-channel-hook erc-kill-server-hook erc-kill-buffer-hook)
-      (erc-mode)
-      (erc-tests--set-fake-server-process "sleep" "1")
-      (erc--initialize-markers (point) nil)
-      (erc-button-mode +1)
-      (should (equal (erc-button--display-error-notice-with-keys
-                      "If \\[erc-bol] fails, "
-                      "see \\[erc-bug] or `erc-mode-map'.")
-                     "*** If C-a fails, see M-x erc-bug or `erc-mode-map'."))
-      (goto-char (point-min))
-
-      (ert-info ("Keymap substitution succeeds")
-        (erc-button-next)
-        (should (looking-at "C-a"))
-        (should (eq (get-text-property (point) 'mouse-face) 'highlight))
-        (erc-button-press-button)
-        (with-current-buffer "*Help*"
-          (goto-char (point-min))
-          (should (search-forward "erc-bol" nil t)))
-        (erc-button-next)
-        (erc-button-previous) ; end of interval correct
-        (should (looking-at "a fails")))
-
-      (ert-info ("Extended command mapping succeeds")
-        (erc-button-next)
-        (should (looking-at "M-x erc-bug"))
-        (erc-button-press-button)
-        (should (eq (get-text-property (point) 'mouse-face) 'highlight))
-        (with-current-buffer "*Help*"
-          (goto-char (point-min))
-          (should (search-forward "erc-bug" nil t))))
-
-      (ert-info ("Symbol-description face preserved") ; mutated by d-e-n-w-k
-        (erc-button-next)
-        (should (equal (get-text-property (point) 'font-lock-face)
-                       '(erc-button erc-error-face)))
-        (should (eq (get-text-property (point) 'mouse-face) 'highlight))
-        (should (eq erc-button-face 'erc-button))) ; extent evaporates
-
-      (ert-info ("Format when trailing args include non-strings")
-        (should (equal (erc-button--display-error-notice-with-keys
-                        "abc" " %d def" " 45%s" 123 '\6)
-                       "*** abc 123 def 456")))
-
-      (when noninteractive
-        (unless mode
-          (erc-button-mode -1))
-        (kill-buffer "*Help*")
-        (kill-buffer)))))
-
 ;;; erc-tests.el ends here