* lisp/emacs-lisp/ert.el (ert--insert-infos): Allow 'message' to be a
function that is called when inserting the info.
(ert-info): Update docstring to describe using a function for
MESSAGE-FORM.
* lisp/server.el (server-start): Log when the server is starting.
* test/lisp/server-tests.el (server-tests/can-create-frames-p): New
constant. Use it to skip tests that need to create frames.
(server-tests/start-emacsclient): Rename to...
(server-tests/start-client): ... this, and set the process's buffer.
(server-tests/with-server): Put the server file in a temporary
directory so we don't conflict with real Emacs servers.
(server-tests/with-client): New macro...
(server-tests/server-start/stop-prompt-with-client)
(server-tests/emacsclient/server-edit)
(server-tests/emacsclient/create-frame)
(server-tests/emacsclient/create-frame): ... use it.
(server-tests/server-start/stop-prompt-with-client): Simplify.
This eliminates a useless error prompt when killing Emacs from a
client frame when there are no other frames (bug#58877).
* lisp/server.el (server-running-external): New error.
(server--file-name): New function...
(server-eval-at): ... use it.
(server-start): Factor out server stopping code into...
(server-stop): ... here.
(server-force-stop): Use 'server-stop', and tell it not to delete
frames.
* test/lisp/server-tests.el
(server-tests/server-force-stop/keeps-frames): New test.
* lisp/server.el (server-mode-map): New keymap...
(server-mode): ... use it.
(server-start): Update the 'server-mode' variable (and sync to
'global-minor-modes') when starting/stopping the server.
* test/lisp/server-tests.el: New file (bug#58909).
