Use advertised PREFIX when formatting nicks in ERC

* lisp/erc/erc-speedbar.el (erc-speedbar-insert-user): Run
`erc-get-channel-membership-prefix' in associated buffer if possible.
* lisp/erc/erc.el (erc-get-channel-membership-prefix): Use known
prefix mappings when determining status chars.
* test/lisp/erc/erc-tests.el (erc--parsed-prefix): Use common helpers
for initializing buffers, and use a more realistic example for PREFIX
value.
(erc--update-channel-modes): Add current buffer to `erc-server-user'
object to maintain essential invariant, even though this doesn't
affect the test's outcome.
(erc-tests--equal-including-properties): Move to `erc-tests-common'
and rename `erc-tests-common-equal-with-props'.
(erc--merge-prop, erc--remove-from-prop-value-list,
erc--remove-from-prop-value-list/many): Use new name for
`erc-tests-common-equal-with-props'.
(erc-get-channel-membership-prefix): New test.
(erc--determine-speaker-message-format-args,
erc--determine-speaker-message-format-args/queries-as-channel,
erc--determine-speaker-message-format-args/queries): Use new name
for `erc-tests-common-equal-with-props'.
* test/lisp/erc/resources/erc-tests-common.el
(erc-tests-common-equal-with-props): New macro, originally
`erc-tests--equal-including-properties' from erc-tests.el.
(erc-tests-common-make-server-buf): Initialize tables and make NAME
argument optional.  (Bug#67677)

lisp/erc/erc-speedbar.el

@@ -319,7 +319,9 @@ a list of four items: the userhost, the GECOS, the current
 	 (info (erc-server-user-info user))
 	 (login (erc-server-user-login user))
 	 (name (erc-server-user-full-name user))
-         (nick-str (concat (erc-get-channel-membership-prefix cuser) nick))
+         (nick-str (concat (with-current-buffer (or buffer (current-buffer))
+                             (erc-get-channel-membership-prefix cuser))
+                           nick))
 	 (finger (concat login (when (or login host) "@") host))
          (sbtoken (list finger name info (buffer-name buffer))))
     (if (or login host name info) ; we want to be expandable

lisp/erc/erc.el

@@ -6130,27 +6130,53 @@ returned name, see `erc-show-speaker-membership-status'."
 
 (define-obsolete-function-alias 'erc-get-user-mode-prefix
   #'erc-get-channel-membership-prefix "30.1")
-(defun erc-get-channel-membership-prefix (user)
-  "Return channel membership prefix for USER as a string.
+(defun erc-get-channel-membership-prefix (nick-or-cusr)
+  "Return channel membership prefix for NICK-OR-CUSR as a string.
 Ensure returned string has a `help-echo' text property with the
 corresponding verbose membership type, like \"voice\", as its
-value.  Expect USER to be an `erc-channel-user' object or a
-string nickname, not necessarily downcased."
-  (when user
-    (when (stringp user)
-      (setq user (and erc-channel-users (cdr (erc-get-channel-user user)))))
-    (cond ((null user) "")
-          ((erc-channel-user-owner user)
-           (propertize "~" 'help-echo "owner"))
-          ((erc-channel-user-admin user)
-           (propertize "&" 'help-echo "admin"))
-          ((erc-channel-user-op user)
-           (propertize "@" 'help-echo "operator"))
-          ((erc-channel-user-halfop user)
-           (propertize "%" 'help-echo "half-op"))
-          ((erc-channel-user-voice user)
-           (propertize "+" 'help-echo "voice"))
-          (t ""))))
+value.  Expect NICK-OR-CUSR to be an `erc-channel-user' object or
+a string nickname, not necessarily downcased.  When called in a
+logically connected ERC buffer, use advertised prefix mappings.
+For compatibility reasons, don't error when NICK-OR-CUSR is null,
+but return nil instead of the empty string.  Otherwise, always
+return a possibly empty string."
+  (when nick-or-cusr
+    (when (stringp nick-or-cusr)
+      (setq nick-or-cusr (and erc-channel-members
+                              (cdr (erc-get-channel-member nick-or-cusr)))))
+    (cond
+     ((null nick-or-cusr) "")
+     ;; Special-case most common value.
+     ((zerop (erc-channel-user-status nick-or-cusr)) "")
+     ;; For compatibility, first check whether a parsed prefix exists.
+     ((and-let* ((pfx-obj (erc--parsed-prefix)))
+        (catch 'done
+          (pcase-dolist (`(,letter . ,pfx)
+                         (erc--parsed-prefix-alist pfx-obj))
+            (pcase letter
+              ((and ?q (guard (erc-channel-user-owner nick-or-cusr)))
+               (throw 'done (propertize (string pfx) 'help-echo "owner")))
+              ((and ?a (guard (erc-channel-user-admin nick-or-cusr)))
+               (throw 'done (propertize (string pfx) 'help-echo "admin")))
+              ((and ?o (guard (erc-channel-user-op nick-or-cusr)))
+               (throw 'done (propertize (string pfx) 'help-echo "operator")))
+              ((and ?h (guard (erc-channel-user-halfop nick-or-cusr)))
+               (throw 'done (propertize (string pfx) 'help-echo "half-op")))
+              ((and ?v (guard (erc-channel-user-voice nick-or-cusr)))
+               (throw 'done (propertize (string pfx) 'help-echo "voice")))))
+          "")))
+     (t
+      (cond ((erc-channel-user-owner nick-or-cusr)
+             (propertize "~" 'help-echo "owner"))
+            ((erc-channel-user-admin nick-or-cusr)
+             (propertize "&" 'help-echo "admin"))
+            ((erc-channel-user-op nick-or-cusr)
+             (propertize "@" 'help-echo "operator"))
+            ((erc-channel-user-halfop nick-or-cusr)
+             (propertize "%" 'help-echo "half-op"))
+            ((erc-channel-user-voice nick-or-cusr)
+             (propertize "+" 'help-echo "voice"))
+            (t ""))))))
 
 (defun erc-format-@nick (&optional user channel-data)
   "Format the nickname of USER showing if USER has a voice, is an

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

@@ -40,6 +40,15 @@
 (require 'ert-x)
 (require 'erc)
 
+
+(defmacro erc-tests-common-equal-with-props (a b)
+  "Compare strings A and B for equality including text props.
+Use `ert-equal-including-properties' on older Emacsen."
+  (list (if (< emacs-major-version 29)
+            'ert-equal-including-properties
+          'equal-including-properties)
+        a b))
+
 ;; Caller should probably shadow `erc-insert-modify-hook' or populate
 ;; user tables for erc-button.
 ;; FIXME explain this comment ^ in more detail or delete.
@@ -98,14 +107,19 @@ recently passed to the mocked `erc-process-input-line'.  Make
         (funcall test-fn (lambda () (pop calls)))))
     (when noninteractive (kill-buffer))))
 
-(defun erc-tests-common-make-server-buf (name)
+(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)
     (erc-tests-common-prep-for-insertion)
     (erc-tests-common-init-server-proc "sleep" "1")
     (setq erc-session-server (concat "irc." name ".org")
           erc-server-announced-name (concat "west." name ".org")
+          erc-server-users (make-hash-table :test #'equal)
+          erc-server-parameters nil
+          erc--isupport-params (make-hash-table)
           erc-session-port 6667
           erc-network (intern name)
           erc-networks--id (erc-networks--id-create nil))