Store one string per user in erc--spkr msg prop

* lisp/erc/erc.el (erc--msg-props): Mention that the `erc--spkr'
msg-prop value is taken from the `nickname' slot of the user's
`erc-server-users' entry.
(erc--speakerize-nick): Avoid using the provided NICK parameter for
the `erc--spkr' property.  Instead, use the version from the
`nickname' slot of its `erc-server-users' item, which is itself an
`erc-server-user' object.  These text props were originally introduced
in ERC 5.6 as part of bug#67677.
* test/lisp/erc/erc-tests.el (erc--refresh-prompt)
(erc--check-prompt-input-functions, erc-send-current-line)
(erc--check-prompt-input-for-multiline-blanks)
(erc-send-whitespace-lines): Use more convenient helper utility to
create fake server buffer where possible.
(erc--speakerize-nick): New test.
* test/lisp/erc/resources/erc-tests-common.el
(erc-tests-common-make-server-buf): Don't use ERT temp buffer's name
for dialed server, etc., because it contains unwanted chars.
(erc-tests-common-with-process-input-spy): Defer to each test to set
up its own prompt, etc.  (Bug#72736)

lisp/erc/erc.el

@@ -173,7 +173,8 @@ as of ERC 5.6:
     and help text, and on outgoing messages unless echoed back by
     the server (assuming future support)
 
- - `erc--spkr': a string, the nick of the person speaking
+ - `erc--spkr': a string, the non-case-mapped nick of the speaker as
+    stored in the `nickname' slot of its `erc-server-users' item
 
  - `erc--ctcp': a CTCP command, like `ACTION'
 
@@ -6339,20 +6340,18 @@ rely on their presence, and cleaner ways exist)."
   "Template for a CTCP ACTION status message from current client.")
 
 (defun erc--speakerize-nick (nick &optional disp)
-  "Propertize NICK with `erc--speaker' if not already present.
-Do so to DISP instead if it's non-nil.  In either case, assign
-NICK, sans properties, as the `erc--speaker' value.  As a side
-effect, pair the latter string (the same `eq'-able object) with
-the symbol `erc--spkr' in the \"msg prop\" environment for any
-imminent `erc-display-message' invocations.  While doing so,
-include any overrides defined in `erc--message-speaker-catalog'."
-  (let ((plain-nick (substring-no-properties nick)))
-    (erc--ensure-spkr-prop plain-nick (get erc--message-speaker-catalog
-                                           'erc--msg-prop-overrides))
-    (if (text-property-not-all 0 (length (or disp nick))
-                               'erc--speaker nil (or disp nick))
-        (or disp nick)
-      (propertize (or disp nick) 'erc--speaker plain-nick))))
+  "Return propertized NICK with canonical NICK in `erc--speaker'.
+Return propertized DISP instead if given.  As a side effect, pair NICK
+with `erc--spkr' in the \"msg prop\" environment for any imminent
+`erc-display-message' invocations, and include any overrides defined in
+`erc--message-speaker-catalog'.  Expect NICK (but not necessarily DISP)
+to be absent of any existing text properties."
+  (when-let ((erc-server-process)
+             (cusr (erc-get-server-user nick)))
+    (setq nick (erc-server-user-nickname cusr)))
+  (erc--ensure-spkr-prop nick (get erc--message-speaker-catalog
+                                   'erc--msg-prop-overrides))
+  (propertize (or disp nick) 'erc--speaker nick))
 
 (defun erc--determine-speaker-message-format-args
     (nick message queryp privmsgp inputp &optional statusmsg prefix disp-nick)

test/lisp/erc/erc-tests.el

@@ -330,16 +330,12 @@
 
     (ert-info ("Server buffer")
       (with-current-buffer (get-buffer-create "ServNet")
-        (erc-tests-common-prep-for-insertion)
+        (erc-tests-common-make-server-buf "ServNet")
         (goto-char erc-insert-marker)
         (should (looking-at-p "ServNet 3>"))
         (erc-tests-common-init-server-proc "sleep" "1")
         (set-process-sentinel erc-server-process #'ignore)
-        (setq erc-network 'ServNet
-              erc-server-current-nick "tester"
-              erc-networks--id (erc-networks--id-create nil)
-              erc-server-users (make-hash-table :test 'equal))
-        (set-process-query-on-exit-flag erc-server-process nil)
+        (setq erc-server-current-nick "tester")
         ;; Incoming message redraws prompt
         (erc-display-message nil 'notice nil "Welcome")
         (should (looking-at-p (rx "*** Welcome")))
@@ -364,6 +360,8 @@
           (should-not (search-forward (rx (any "3-5") ">") nil t)))))
 
     (ert-info ("Channel buffer")
+      ;; Create buffer manually instead of using `erc--open-target' in
+      ;; order to show prompt before/after network is known.
       (with-current-buffer (get-buffer-create "#chan")
         (erc-tests-common-prep-for-insertion)
         (goto-char erc-insert-marker)
@@ -1521,6 +1519,7 @@
 (ert-deftest erc--check-prompt-input-functions ()
   (erc-tests-common-with-process-input-spy
    (lambda (next)
+     (erc-tests-common-prep-for-insertion)
 
      (ert-info ("Errors when point not in prompt area") ; actually just dings
        (insert "/msg #chan hi")
@@ -1556,7 +1555,7 @@
 (ert-deftest erc-send-current-line ()
   (erc-tests-common-with-process-input-spy
    (lambda (next)
-     (erc-tests-common-init-server-proc "sleep" "1")
+     (erc-tests-common-make-server-buf (buffer-name))
      (should (= 0 erc-last-input-time))
 
      (ert-info ("Simple command")
@@ -1639,7 +1638,8 @@
   (ert-with-message-capture messages
     (erc-tests-common-with-process-input-spy
      (lambda (next)
-       (erc-tests-common-init-server-proc "sleep" "300")
+       (erc-tests-common-make-server-buf (buffer-name))
+
        (should-not erc-send-whitespace-lines)
        (should erc-warn-about-blank-lines)
 
@@ -1717,7 +1717,8 @@
 (ert-deftest erc-send-whitespace-lines ()
   (erc-tests-common-with-process-input-spy
    (lambda (next)
-     (erc-tests-common-init-server-proc "sleep" "1")
+     (erc-tests-common-make-server-buf (buffer-name))
+
      (setq-local erc-send-whitespace-lines t)
 
      (ert-info ("Multiline hunk with blank line correctly split")
@@ -2653,6 +2654,58 @@
            (erc--determine-speaker-message-format-args nick msg privp msgp
                                                        inputp nil pfx))))
 
+;; This test demonstrates that ERC uses the same string for the
+;; `erc--spkr' and `erc--speaker' text properties, which it gets from
+;; the `nickname' shot of the speaker's server user.
+(ert-deftest erc--speakerize-nick ()
+  (erc-tests-common-make-server-buf)
+  (setq erc-server-current-nick "tester")
+
+  (let ((sentinel "alice"))
+    (with-current-buffer (erc--open-target "#chan")
+      (erc-update-current-channel-member "bob" "bob" t nil nil nil nil nil
+                                         "example.org" "~u" "bob")
+      (erc-update-current-channel-member "alice" sentinel t nil nil nil nil nil
+                                         "fsf.org" "~u" "alice"))
+
+    (erc-call-hooks nil (make-erc-response
+                         :sender "alice!~u@fsf.org"
+                         :command "PRIVMSG"
+                         :command-args '("#chan" "one")
+                         :contents "one"
+                         :unparsed ":alice!~u@fsf.org PRIVMSG #chan :one"))
+    (erc-call-hooks nil (make-erc-response
+                         :sender "bob!~u@example.org"
+                         :command "PRIVMSG"
+                         :command-args '("#chan" "hi")
+                         :contents "hi"
+                         :unparsed ":bob!~u@example.org PRIVMSG #chan :hi"))
+    (erc-call-hooks nil (make-erc-response
+                         :sender "alice!~u@fsf.org"
+                         :command "PRIVMSG"
+                         :command-args '("#chan" "two")
+                         :contents "two"
+                         :unparsed ":alice!~u@fsf.org PRIVMSG #chan :two"))
+
+    (with-current-buffer (get-buffer "#chan")
+      (should (eq sentinel
+                  (erc-server-user-nickname (erc-get-server-user "alice"))))
+      (goto-char (point-min))
+
+      (should (search-forward "<a" nil t))
+      (should (looking-at "lice> one"))
+      (should (eq (get-text-property (point) 'erc--speaker) sentinel))
+      (should (eq (erc--get-inserted-msg-prop 'erc--spkr) sentinel))
+
+      (should (search-forward "<bob> hi" nil t))
+
+      (should (search-forward "<a" nil t))
+      (should (looking-at "lice> two"))
+      (should (eq (get-text-property (point) 'erc--speaker) sentinel))
+      (should (eq (erc--get-inserted-msg-prop 'erc--spkr) sentinel))
+
+      (when noninteractive (kill-buffer)))))
+
 ;; This asserts that `erc--determine-speaker-message-format-args'
 ;; behaves identically to `erc-format-privmessage', the function whose
 ;; role it basically replaced.

test/lisp/erc/resources/erc-tests-common.el

@@ -103,16 +103,17 @@ recently passed to the mocked `erc-process-input-line'.  Make
                  (lambda (&rest r) (push r calls)))
                 ((symbol-function 'erc-server-buffer)
                  (lambda () (current-buffer))))
-        (erc-tests-common-prep-for-insertion)
         (funcall test-fn (lambda () (pop calls)))))
     (when noninteractive (kill-buffer))))
 
 (defun erc-tests-common-make-server-buf (&optional name)
   "Return a server buffer named NAME, creating it if necessary.
 Use NAME for the network and the session server as well."
-  (unless name
-    (cl-assert (string-prefix-p " *temp*" (setq name (buffer-name)))))
-  (with-current-buffer (get-buffer-create name)
+  (with-current-buffer (if name
+                           (get-buffer-create name)
+                         (and (string-search "temp" (buffer-name))
+                              (setq name "foonet")
+                              (buffer-name)))
     (erc-tests-common-prep-for-insertion)
     (erc-tests-common-init-server-proc "sleep" "1")
     (setq erc-session-server (concat "irc." name ".org")