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diff --git a/test/lisp/erc/erc-networks-tests.el b/test/lisp/erc/erc-networks-tests.el
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+++ b/test/lisp/erc/erc-networks-tests.el
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+;;; erc-networks-tests.el --- Tests for erc-networks.  -*- lexical-binding:t -*-
+
+;; Copyright (C) 2020-2022 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/>.
+
+;;; Code:
+
+(require 'ert-x) ; cl-lib
+(require 'erc-networks)
+
+(defun erc-networks-tests--create-dead-proc (&optional buf)
+  (let ((p (start-process "true" (or buf (current-buffer)) "true")))
+    (while (process-live-p p) (sit-for 0.1))
+    p))
+
+(defun erc-networks-tests--create-live-proc (&optional buf)
+  (let ((proc (start-process "sleep" (or buf (current-buffer)) "sleep" "1")))
+    (set-process-query-on-exit-flag proc nil)
+    proc))
+
+;; When we drop 27, call `get-buffer-create with INHIBIT-BUFFER-HOOKS.
+(defun erc-networks-tests--clean-bufs ()
+  (let (erc-kill-channel-hook
+        erc-kill-server-hook
+        erc-kill-buffer-hook)
+    (dolist (buf (erc-buffer-list))
+      (kill-buffer buf))))
+
+(defun erc-networks-tests--bufnames (prefix)
+  (let* ((case-fold-search)
+         (pred (lambda (b) (string-prefix-p prefix (buffer-name b))))
+         (prefixed (seq-filter pred (buffer-list))))
+    (sort (mapcar #'buffer-name prefixed) #'string<)))
+
+(ert-deftest erc-networks--id ()
+  (cl-letf (((symbol-function 'float-time)
+             (lambda (&optional _) 0.0)))
+
+    ;; Fixed
+    (should (equal (erc-networks--id-fixed-create 'foo)
+                   (make-erc-networks--id-fixed :ts (float-time)
+                                                :symbol 'foo)))
+
+    ;; Eliding
+    (let* ((erc-network 'FooNet)
+           (erc-server-current-nick "Joe")
+           (identity (erc-networks--id-create nil)))
+
+      (should (equal identity #s(erc-networks--id-qualifying
+                                 0.0 FooNet [FooNet "joe"] 1)))
+      (should (equal (erc-networks--id-qualifying-grow-id identity)
+                     'FooNet/joe))
+      (should (equal identity #s(erc-networks--id-qualifying
+                                 0.0 FooNet/joe [FooNet "joe"] 2)))
+      (should-not (erc-networks--id-qualifying-grow-id identity))
+      (should (equal identity #s(erc-networks--id-qualifying
+                                 0.0 FooNet/joe [FooNet "joe"] 2))))
+
+    ;; Compat
+    (with-current-buffer (get-buffer-create "fake.chat")
+      (with-suppressed-warnings ((obsolete erc-rename-buffers))
+        (let (erc-rename-buffers)
+          (should (equal (erc-networks--id-create nil)
+                         (make-erc-networks--id-fixed :ts (float-time)
+                                                      :symbol 'fake.chat)))))
+      (kill-buffer))))
+
+(ert-deftest erc-networks--id-create ()
+  (cl-letf (((symbol-function 'float-time)
+             (lambda (&optional _) 0.0)))
+
+    (should (equal (erc-networks--id-create 'foo)
+                   (make-erc-networks--id-fixed :ts (float-time)
+                                                :symbol 'foo)))
+    (should (equal (erc-networks--id-create "foo")
+                   (make-erc-networks--id-fixed :ts (float-time)
+                                                :symbol 'foo)))
+    (should (equal (erc-networks--id-create [h i])
+                   (make-erc-networks--id-fixed :ts (float-time)
+                                                :symbol (quote \[h\ \i\]))))
+
+    (with-current-buffer (get-buffer-create "foo")
+      (let ((expected (make-erc-networks--id-fixed :ts (float-time)
+                                                   :symbol 'foo)))
+        (with-suppressed-warnings ((obsolete erc-rename-buffers))
+          (let (erc-rename-buffers)
+            (should (equal (erc-networks--id-create nil) expected))))
+        (with-suppressed-warnings ((obsolete erc-reuse-buffers))
+          (let (erc-reuse-buffers)
+            (should (equal (erc-networks--id-create nil) expected))
+            (should (equal (erc-networks--id-create 'bar) expected)))))
+      (kill-buffer))))
+
+(ert-deftest erc-networks--id-qualifying-prefix-length ()
+  (should-not (erc-networks--id-qualifying-prefix-length
+               (make-erc-networks--id-qualifying)
+               (make-erc-networks--id-qualifying)))
+
+  (should-not (erc-networks--id-qualifying-prefix-length
+               (make-erc-networks--id-qualifying :parts [1 2])
+               (make-erc-networks--id-qualifying :parts [2 3])))
+
+  (should (= 1 (erc-networks--id-qualifying-prefix-length
+                (make-erc-networks--id-qualifying :parts [1])
+                (make-erc-networks--id-qualifying :parts [1 2]))))
+
+  (should (= 1 (erc-networks--id-qualifying-prefix-length
+                (make-erc-networks--id-qualifying :parts [1 2])
+                (make-erc-networks--id-qualifying :parts [1 3]))))
+
+  (should (= 2 (erc-networks--id-qualifying-prefix-length
+                (make-erc-networks--id-qualifying :parts [1 2])
+                (make-erc-networks--id-qualifying :parts [1 2]))))
+
+  (should (= 1 (erc-networks--id-qualifying-prefix-length
+                (make-erc-networks--id-qualifying :parts ["1"])
+                (make-erc-networks--id-qualifying :parts ["1"])))))
+
+(ert-deftest erc-networks--id-sort-buffers ()
+  (let (oldest middle newest)
+
+    (with-temp-buffer
+      (setq erc-networks--id (erc-networks--id-fixed-create 'oldest)
+            oldest (current-buffer))
+
+      (with-temp-buffer
+        (setq erc-networks--id (erc-networks--id-fixed-create 'middle)
+              middle (current-buffer))
+
+        (with-temp-buffer
+          (setq erc-networks--id (erc-networks--id-fixed-create 'newest)
+                newest (current-buffer))
+
+          (should (equal (erc-networks--id-sort-buffers
+                          (list oldest newest middle))
+                         (list newest middle oldest))))))))
+
+(ert-deftest erc-networks-rename-surviving-target-buffer--channel ()
+  (should (memq #'erc-networks-rename-surviving-target-buffer
+                erc-kill-channel-hook))
+
+  (let ((chan-foonet-buffer (get-buffer-create "#chan@foonet")))
+
+    (with-current-buffer chan-foonet-buffer
+      (erc-mode)
+      (setq erc-networks--id (make-erc-networks--id-qualifying
+                              :parts [foonet "bob"] :len 1)
+            erc--target (erc--target-from-string "#chan")))
+
+    (with-current-buffer (get-buffer-create "#chan@barnet")
+      (erc-mode)
+      (setq erc-networks--id (make-erc-networks--id-qualifying
+                              :parts [barnet "bob"] :len 1)
+            erc--target (erc--target-from-string "#chan")))
+
+    (kill-buffer "#chan@barnet")
+    (should (equal (erc-networks-tests--bufnames "#chan") '("#chan")))
+    (should (eq chan-foonet-buffer (get-buffer "#chan"))))
+
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks-rename-surviving-target-buffer--query ()
+  (should (memq #'erc-networks-rename-surviving-target-buffer
+                erc-kill-buffer-hook))
+
+  (let ((bob-foonet (get-buffer-create "bob@foonet")))
+
+    (with-current-buffer bob-foonet
+      (erc-mode)
+      (setq erc-networks--id (make-erc-networks--id-qualifying
+                              :parts [foonet "bob"] :len 1)
+            erc--target (erc--target-from-string "bob")))
+
+    (with-current-buffer (get-buffer-create "bob@barnet")
+      (erc-mode)
+      (setq erc-networks--id (make-erc-networks--id-qualifying
+                              :parts [barnet "bob"] :len 1)
+            erc--target (erc--target-from-string "bob")))
+
+    (kill-buffer "bob@barnet")
+    (should (equal (erc-networks-tests--bufnames "bob") '("bob")))
+    (should (eq bob-foonet (get-buffer "bob"))))
+
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks-rename-surviving-target-buffer--multi ()
+
+  (ert-info ("Multiple leftover channels untouched")
+    (with-current-buffer (get-buffer-create "#chan@foonet")
+      (erc-mode)
+      (setq erc--target (erc--target-from-string "#chan")))
+    (with-current-buffer (get-buffer-create "#chan@barnet")
+      (erc-mode)
+      (setq erc--target (erc--target-from-string "#chan")))
+    (with-current-buffer (get-buffer-create "#chan@baznet")
+      (erc-mode)
+      (setq erc--target (erc--target-from-string "#chan")))
+    (kill-buffer "#chan@baznet")
+    (should (equal (erc-networks-tests--bufnames "#chan")
+                   '("#chan@barnet" "#chan@foonet")))
+    (erc-networks-tests--clean-bufs))
+
+  (ert-info ("Multiple leftover queries untouched")
+    (with-current-buffer (get-buffer-create "bob@foonet")
+      (erc-mode)
+      (setq erc--target (erc--target-from-string "bob")))
+    (with-current-buffer (get-buffer-create "bob@barnet")
+      (erc-mode)
+      (setq erc--target (erc--target-from-string "bob")))
+    (with-current-buffer (get-buffer-create "bob@baznet")
+      (erc-mode)
+      (setq erc--target (erc--target-from-string "bob")))
+    (kill-buffer "bob@baznet")
+    (should (equal (erc-networks-tests--bufnames "bob")
+                   '("bob@barnet" "bob@foonet")))
+    (erc-networks-tests--clean-bufs)))
+
+;; As of May 2022, this "shrink" stuff runs whenever an ERC buffer is
+;; killed because `erc-networks-shrink-ids-and-buffer-names' is a
+;; default member of all three erc-kill-* functions.
+
+;; Note: this overlaps a fair bit with the "hook" variants, i.e.,
+;; `erc-networks--shrink-ids-and-buffer-names--hook-outstanding-*' If
+;; this ever fails, just delete this and fix those.  But please copy
+;; over and adapt the comments first.
+
+(ert-deftest erc-networks--shrink-ids-and-buffer-names--perform-outstanding ()
+  ;; While some buffer #a@barnet/dummy is being killed, its display ID
+  ;; is not collapsed because collisions still exist.
+  ;;
+  ;; Note that we don't have to set `erc-server-connected' because
+  ;; this function is intentionally connectivity agnostic.
+  (with-current-buffer (get-buffer-create "foonet/tester")
+    (erc-mode)
+    (setq erc-server-current-nick "tester" ; Always set (`erc-open')
+          ;; Set when transport connected
+          erc-server-process (erc-networks-tests--create-live-proc)
+          ;; Both set just before IRC (logically) connected (post MOTD)
+          erc-network 'foonet
+          erc-networks--id (make-erc-networks--id-qualifying
+                            :symbol 'foonet/tester
+                            :parts [foonet "tester"]
+                            :len 2))) ; is/was a plain foonet collision
+
+  ;; Presumably, some server buffer named foonet/dummy was just
+  ;; killed, hence the length 2 display ID.
+
+  ;; A target buffer for chan #a exists for foonet/tester.  The
+  ;; precise form of its name should not affect shrinking.
+  (with-current-buffer (get-buffer-create
+                        (elt ["#a" "#a@foonet" "#a@foonet/tester"] (random 3)))
+    (erc-mode)
+    (setq erc-server-process (buffer-local-value 'erc-server-process
+                                                 (get-buffer "foonet/tester"))
+          erc-network 'foonet
+          erc-server-current-nick "tester"
+          erc-networks--id (buffer-local-value 'erc-networks--id
+                                               (get-buffer "foonet/tester"))
+          erc--target (erc--target-from-string "#a")))
+
+  ;; Another network context exists (so we have buffers to iterate
+  ;; over), and it's also part of a collision group.
+  (with-current-buffer (get-buffer-create "barnet/tester")
+    (erc-mode)
+    (setq erc-network 'barnet
+          erc-server-current-nick "tester"
+          erc-networks--id (make-erc-networks--id-qualifying
+                            :symbol 'barnet/tester
+                            :parts [barnet "tester"]
+                            :len 2)
+          erc-server-process (erc-networks-tests--create-live-proc)))
+
+  (with-current-buffer (get-buffer-create "barnet/dummy")
+    (erc-mode)
+    (setq erc-network 'barnet
+          erc-server-current-nick "dummy"
+          erc-networks--id (make-erc-networks--id-qualifying
+                            :symbol 'barnet/dummy
+                            :parts [barnet "dummy"]
+                            :len 2)
+          erc-server-process (erc-networks-tests--create-live-proc)))
+
+  ;; The buffer being killed is not part of the foonet collision
+  ;; group, which contains one display ID eligible for shrinkage.
+  (with-current-buffer (get-buffer-create
+                        (elt ["#a@barnet" "#a@barnet/tester"] (random 2)))
+    (erc-mode)
+    (setq erc-network 'barnet
+          erc-server-current-nick "tester"
+          erc-server-process (buffer-local-value 'erc-server-process
+                                                 (get-buffer "barnet/tester"))
+          erc-networks--id (buffer-local-value 'erc-networks--id
+                                               (get-buffer "barnet/tester"))
+          erc--target (erc--target-from-string "#a")))
+
+  (with-temp-buffer ; doesn't matter what the current buffer is
+    (setq erc-networks--id (make-erc-networks--id-qualifying)) ; mock
+    (erc-networks--shrink-ids-and-buffer-names))
+
+  (should (equal (mapcar #'buffer-name (erc-buffer-list))
+                 '("foonet" ; shrunk
+                   "#a@foonet" ; shrunk
+                   "barnet/tester"
+                   "barnet/dummy"
+                   "#a@barnet/tester")))
+
+  (erc-networks-tests--clean-bufs))
+
+;; This likewise overlaps with the "hook" variants below.  If this
+;; should ever fail, just delete it and optionally fix those.
+
+(ert-deftest erc-networks--shrink-ids-and-buffer-names--perform-collapse ()
+  ;; This is similar to the "outstanding" variant above, but both
+  ;; groups are eligible for renaming, which is abnormal but possible
+  ;; when recovering from some mishap.
+  (with-current-buffer (get-buffer-create "foonet/tester")
+    (erc-mode)
+    (setq erc-network 'foonet
+          erc-server-current-nick "tester"
+          erc-networks--id (make-erc-networks--id-qualifying
+                            :symbol 'foonet/tester
+                            :parts [foonet "tester"]
+                            :len 2)
+          erc-server-process (erc-networks-tests--create-live-proc)))
+
+  (with-current-buffer
+      (get-buffer-create (elt ["#a" "#a@foonet/tester"] (random 2)))
+    (erc-mode)
+    (setq erc-server-process (buffer-local-value 'erc-server-process
+                                                 (get-buffer "foonet/tester"))
+          erc-network 'foonet
+          erc-server-current-nick "tester"
+          erc-networks--id (buffer-local-value 'erc-networks--id
+                                               (get-buffer "foonet/tester"))
+          erc--target (erc--target-from-string "#a")))
+
+  (with-current-buffer (get-buffer-create "barnet/tester")
+    (erc-mode)
+    (setq erc-network 'barnet
+          erc-server-current-nick "tester"
+          erc-networks--id (make-erc-networks--id-qualifying
+                            :symbol 'barnet/tester
+                            :parts [barnet "tester"]
+                            :len 2)
+          erc-server-process (erc-networks-tests--create-live-proc)))
+
+  (with-current-buffer
+      (get-buffer-create (elt ["#b" "#b@foonet/tester"] (random 2)))
+    (erc-mode)
+    (setq erc-network 'barnet
+          erc-server-current-nick "tester"
+          erc-server-process (buffer-local-value 'erc-server-process
+                                                 (get-buffer "barnet/tester"))
+          erc-networks--id (buffer-local-value 'erc-networks--id
+                                               (get-buffer "barnet/tester"))
+          erc--target (erc--target-from-string "#b")))
+
+  (with-temp-buffer
+    (setq erc-networks--id (make-erc-networks--id-qualifying))
+    (erc-networks--shrink-ids-and-buffer-names))
+
+  (should (equal (mapcar #'buffer-name (erc-buffer-list))
+                 '("foonet" "#a" "barnet" "#b")))
+
+  (erc-networks-tests--clean-bufs))
+
+(defun erc-networks--shrink-ids-and-buffer-names--hook-outstanding-common ()
+
+  (with-current-buffer (get-buffer-create "foonet/tester")
+    (erc-mode)
+    (setq erc-network 'foonet
+          erc-server-current-nick "tester"
+          erc-networks--id (make-erc-networks--id-qualifying
+                            :symbol 'foonet/tester
+                            :parts [foonet "tester"]
+                            :len 2)
+          erc-server-process (erc-networks-tests--create-live-proc)))
+
+  (with-current-buffer (get-buffer-create "#a@foonet/tester")
+    (erc-mode)
+    (setq erc-server-process (buffer-local-value 'erc-server-process
+                                                 (get-buffer "foonet/tester"))
+          erc-network 'foonet
+          erc-server-current-nick "tester"
+          erc-networks--id (buffer-local-value 'erc-networks--id
+                                               (get-buffer "foonet/tester"))
+          erc--target (erc--target-from-string "#a")))
+
+  (with-current-buffer (get-buffer-create "barnet/tester")
+    (erc-mode)
+    (setq erc-network 'barnet
+          erc-server-current-nick "tester"
+          erc-networks--id (make-erc-networks--id-qualifying
+                            :symbol 'barnet/tester
+                            :parts [barnet "tester"]
+                            :len 2)
+          erc-server-process (erc-networks-tests--create-live-proc)))
+
+  (with-current-buffer (get-buffer-create "barnet/dummy")
+    (erc-mode)
+    (setq erc-network 'barnet
+          erc-server-current-nick "dummy"
+          erc-networks--id (make-erc-networks--id-qualifying
+                            :symbol 'barnet/dummy
+                            :parts [barnet "dummy"]
+                            :len 2)
+          erc-server-process (erc-networks-tests--create-live-proc)))
+
+  (with-current-buffer (get-buffer-create "#a@barnet/tester")
+    (erc-mode)
+    (setq erc-network 'barnet
+          erc-server-current-nick "tester"
+          erc-server-process (buffer-local-value 'erc-server-process
+                                                 (get-buffer "barnet/tester"))
+          erc-networks--id (buffer-local-value 'erc-networks--id
+                                               (get-buffer "barnet/tester"))
+          erc--target (erc--target-from-string "#a"))))
+
+(ert-deftest erc-networks--shrink-ids-and-buffer-names--hook-outstanding-srv ()
+  (erc-networks--shrink-ids-and-buffer-names--hook-outstanding-common)
+  (with-current-buffer (get-buffer-create "foonet/dummy")
+    (erc-mode)
+    (setq erc-network 'foonet
+          erc-server-current-nick "dummy"
+          erc-networks--id (make-erc-networks--id-qualifying
+                            :symbol 'foonet/dummy
+                            :parts [foonet "dummy"]
+                            :len 2)
+          erc-server-process (erc-networks-tests--create-live-proc))
+    (kill-buffer))
+
+  (should (equal (mapcar #'buffer-name (erc-buffer-list))
+                 '("foonet"
+                   "#a@foonet"
+                   "barnet/tester"
+                   "barnet/dummy"
+                   "#a@barnet/tester")))
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks--shrink-ids-and-buffer-names--hook-outstanding-tgt ()
+  (erc-networks--shrink-ids-and-buffer-names--hook-outstanding-common)
+  (with-current-buffer (get-buffer-create "#a@foonet/dummy")
+    (erc-mode)
+    (setq erc-network 'foonet
+          erc-server-current-nick "dummy"
+          erc-networks--id (make-erc-networks--id-qualifying
+                            :symbol 'foonet/dummy
+                            :parts [foonet "dummy"]
+                            :len 2)
+          erc--target (erc--target-from-string "#a")
+          erc-server-process (with-temp-buffer
+                               (erc-networks-tests--create-dead-proc))))
+
+  (with-current-buffer "#a@foonet/dummy" (kill-buffer))
+
+  ;; Identical to *-server variant above
+  (should (equal (mapcar #'buffer-name (erc-buffer-list))
+                 '("foonet"
+                   "#a@foonet"
+                   "barnet/tester"
+                   "barnet/dummy"
+                   "#a@barnet/tester")))
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks-rename-surviving-target-buffer--shrink ()
+  (erc-networks--shrink-ids-and-buffer-names--hook-outstanding-common)
+
+  ;; This buffer isn't "#a@foonet" (yet) because the shrink-ids hook
+  ;; hasn't run.  However, when it's the rename hook runs, its network
+  ;; id *is* "foonet", not "foonet/tester".
+  (with-current-buffer "#a@foonet/tester" (kill-buffer))
+
+  (should (equal (mapcar #'buffer-name (erc-buffer-list))
+                 '("foonet"
+                   "barnet/tester"
+                   "barnet/dummy"
+                   "#a")))
+
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks--shrink-ids-and-buffer-names--server ()
+
+  (with-current-buffer (get-buffer-create "foonet/tester")
+    (erc-mode)
+    (setq erc-network 'foonet
+          erc-server-current-nick "tester"
+          erc-networks--id (make-erc-networks--id-qualifying
+                            :symbol 'foonet/tester
+                            :parts [foonet "tester"]
+                            :len 2)
+          erc-server-process (erc-networks-tests--create-live-proc)))
+
+  (with-current-buffer (get-buffer-create "foonet/dummy")
+    (erc-mode)
+    (setq erc-network 'foonet
+          erc-server-current-nick "dummy"
+          erc-networks--id (make-erc-networks--id-qualifying
+                            :symbol 'foonet/dummy
+                            :parts [foonet "dummy"]
+                            :len 2)
+          erc-server-process (erc-networks-tests--create-dead-proc))
+    (kill-buffer))
+
+  (should (equal (mapcar #'buffer-name (erc-buffer-list)) '("foonet")))
+
+  (erc-networks-tests--clean-bufs))
+
+(defun erc-networks--shrink-ids-and-buffer-names--hook-collapse (check)
+
+  (with-current-buffer (get-buffer-create "foonet/tester")
+    (erc-mode)
+    (setq erc-network 'foonet
+          erc-server-current-nick "tester"
+          erc-networks--id (make-erc-networks--id-qualifying
+                            :symbol 'foonet/tester
+                            :parts [foonet "tester"]
+                            :len 2)
+          erc-server-process (erc-networks-tests--create-live-proc)))
+
+  (with-current-buffer (get-buffer-create "#a@foonet/tester")
+    (erc-mode)
+    (setq erc-server-process (buffer-local-value 'erc-server-process
+                                                 (get-buffer "foonet/tester"))
+          erc-network 'foonet
+          erc-server-current-nick "tester"
+          erc-networks--id (buffer-local-value 'erc-networks--id
+                                               (get-buffer "foonet/tester"))
+          erc--target (erc--target-from-string "#a")))
+
+  (with-current-buffer (get-buffer-create "barnet/tester")
+    (erc-mode)
+    (setq erc-network 'barnet
+          erc-server-current-nick "tester"
+          erc-networks--id (make-erc-networks--id-qualifying
+                            :symbol 'barnet/tester
+                            :parts [barnet "tester"]
+                            :len 2)
+          erc-server-process (erc-networks-tests--create-live-proc)))
+
+  (with-current-buffer (get-buffer-create  "#b@foonet/tester")
+    (erc-mode)
+    (setq erc-network 'barnet
+          erc-server-current-nick "tester"
+          erc-server-process (buffer-local-value 'erc-server-process
+                                                 (get-buffer "barnet/tester"))
+          erc-networks--id (buffer-local-value 'erc-networks--id
+                                               (get-buffer "barnet/tester"))
+          erc--target (erc--target-from-string "#b")))
+
+  (funcall check)
+
+  (should (equal (mapcar #'buffer-name (erc-buffer-list))
+                 '("foonet" "#a" "barnet" "#b")))
+
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks--shrink-ids-and-buffer-names--hook-collapse-server ()
+  (erc-networks--shrink-ids-and-buffer-names--hook-collapse
+   (lambda ()
+     (with-current-buffer (get-buffer-create "foonet/dummy")
+       (erc-mode)
+       (setq erc-network 'foonet
+             erc-server-current-nick "dummy"
+             erc-networks--id (make-erc-networks--id-qualifying
+                               :symbol 'foonet/dummy
+                               :parts [foonet "dummy"]
+                               :len 2)
+             erc-server-process (erc-networks-tests--create-live-proc))
+       (kill-buffer)))))
+
+(ert-deftest erc-networks--shrink-ids-and-buffer-names--hook-collapse-target ()
+  (erc-networks--shrink-ids-and-buffer-names--hook-collapse
+   (lambda ()
+     (with-current-buffer (get-buffer-create "#a@foonet/dummy")
+       (erc-mode)
+       (setq erc-network 'foonet
+             erc-server-current-nick "dummy"
+             erc-networks--id (make-erc-networks--id-qualifying
+                               :symbol 'foonet/dummy
+                               :parts [foonet "dummy"]
+                               :len 2)
+             ;; `erc-kill-buffer-function' uses legacy target detection
+             ;; but falls back on buffer name, so no need for:
+             ;;
+             ;;   erc-default-recipients '("#a")
+             ;;
+             erc--target (erc--target-from-string "#a")
+             erc-server-process (with-temp-buffer
+                                  (erc-networks-tests--create-dead-proc)))
+       (kill-buffer)))))
+
+;; FIXME this test is old and may describe impossible states:
+;; leftover identities being qual-equal but not eq (implies
+;; `erc-networks--reclaim-orphaned-target-buffers' is somehow broken).
+;;
+;; Otherwise, the point of this test is to show that server process
+;; identity does not impact the hunt for duplicates.
+
+(defun erc-tests--prep-erc-networks--reconcile-buffer-names--duplicates (start)
+
+  (with-current-buffer (get-buffer-create "foonet")
+    (erc-mode)
+    (setq erc-network 'foonet
+          erc-server-current-nick "tester"
+          erc-networks--id (erc-networks--id-create nil)
+          erc-server-process (funcall start)))
+
+  (with-current-buffer (get-buffer-create "#chan") ; prior session
+    (erc-mode)
+    (setq erc-server-process (buffer-local-value 'erc-server-process
+                                                 (get-buffer "foonet"))
+          erc--target (erc--target-from-string "#chan")
+          erc-networks--id (erc-networks--id-create nil)))
+
+  (ert-info ("Conflicts not recognized as ERC buffers and not renamed")
+    (get-buffer-create "#chan@foonet")
+    (should (equal (erc-networks-tests--bufnames "#chan")
+                   '("#chan" "#chan@foonet"))))
+
+  ;; These are dupes (not "collisions")
+
+  (with-current-buffer "#chan@foonet" ; same proc
+    (erc-mode)
+    (setq erc--target (erc--target-from-string "#chan")
+          erc-network 'foonet
+          erc-server-current-nick "tester"
+          erc-server-process (buffer-local-value 'erc-server-process
+                                                 (get-buffer "foonet"))
+          erc-networks--id (erc-networks--id-create nil)))
+
+  (with-current-buffer (get-buffer-create "#chan@foonet<dead>")
+    (erc-mode)
+    (setq erc--target (erc--target-from-string "#chan")
+          erc-server-process (erc-networks-tests--create-dead-proc)
+          erc-network 'foonet
+          erc-server-current-nick "tester"
+          erc-networks--id (erc-networks--id-create nil)))
+
+  (with-current-buffer (get-buffer-create "#chan@foonet<live>")
+    (erc-mode)
+    (setq erc--target (erc--target-from-string "#chan")
+          erc-server-process (erc-networks-tests--create-live-proc)
+          erc-network 'foonet
+          erc-server-current-nick "tester"
+          erc-networks--id (erc-networks--id-create nil)))
+
+  (let ((created (list (get-buffer "#chan@foonet<live>")
+                       (get-buffer "#chan@foonet<dead>")
+                       (get-buffer "#chan@foonet"))))
+
+    (with-current-buffer "foonet"
+      (should (string= (erc-networks--reconcile-buffer-names
+                        (erc--target-from-string "#chan") erc-networks--id)
+                       "#chan")))
+
+    (ert-info ("All buffers considered dupes renamed")
+      (should (equal (erc-networks-tests--bufnames "#chan")
+                     '("#chan" "#chan<2>" "#chan<3>" "#chan<4>"))))
+
+    (ert-info ("All buffers renamed from newest to oldest")
+      (should (equal created (list (get-buffer "#chan<2>")
+                                   (get-buffer "#chan<3>")
+                                   (get-buffer "#chan<4>"))))))
+
+  (erc-networks-tests--clean-bufs))
+
+(defun erc-tests--prep-erc-networks--reconcile-buffer-names--dupes-given (go)
+
+  ;; The connection's network is discovered before target buffers are
+  ;; created.  This shows that the network doesn't matter when only
+  ;; "given" IDs are present.
+  (with-current-buffer (get-buffer-create "oofnet")
+    (erc-mode)
+    (setq erc-networks--id (erc-networks--id-create 'oofnet)
+          erc-network 'foonet
+          erc-server-current-nick "tester"
+          erc-server-process (funcall go)))
+
+  (with-current-buffer (get-buffer-create "#chan") ; prior session
+    (erc-mode)
+    (setq erc-networks--id (erc-networks--id-create 'oofnet)
+          erc-server-process (buffer-local-value 'erc-server-process
+                                                 (get-buffer "oofnet"))
+          erc--target (erc--target-from-string "#chan")))
+
+  (with-current-buffer (get-buffer-create "#chan@oofnet") ;dupe/not collision
+    (erc-mode)
+    (setq erc-networks--id (erc-networks--id-create 'oofnet)
+          erc-server-process (buffer-local-value 'erc-server-process
+                                                 (get-buffer "oofnet"))
+          erc--target (erc--target-from-string "#chan")))
+
+  (with-current-buffer "oofnet"
+    (should (string= (erc-networks--reconcile-buffer-names
+                      (erc--target-from-string "#chan") erc-networks--id)
+                     "#chan")))
+
+  (ert-info ("All buffers matching target and network renamed")
+    (should (equal (erc-networks-tests--bufnames "#chan")
+                   '("#chan" "#chan<2>"))))
+
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks--reconcile-buffer-names--duplicates ()
+  (ert-info ("Process live, no error")
+    (erc-tests--prep-erc-networks--reconcile-buffer-names--duplicates
+     #'erc-networks-tests--create-live-proc))
+
+  (ert-info ("Process live, no error, given ID")
+    (erc-tests--prep-erc-networks--reconcile-buffer-names--dupes-given
+     #'erc-networks-tests--create-live-proc))
+
+  (ert-info ("Process dead")
+    (erc-tests--prep-erc-networks--reconcile-buffer-names--duplicates
+     #'erc-networks-tests--create-dead-proc))
+
+  (ert-info ("Process dead, given ID")
+    (erc-tests--prep-erc-networks--reconcile-buffer-names--dupes-given
+     #'erc-networks-tests--create-dead-proc)))
+
+(defun erc-tests--prep-erc-networks--reconcile-buffer-names--no-srv-buf (check)
+  (let ((foonet-proc (with-temp-buffer
+                       (erc-networks-tests--create-dead-proc))))
+    (with-current-buffer (get-buffer-create "barnet")
+      (erc-mode)
+      (setq erc-network 'barnet
+            erc-server-current-nick "tester"
+            erc-networks--id (erc-networks--id-create nil)
+            erc-server-process (erc-networks-tests--create-dead-proc)))
+
+    ;; Different proc and not "qual-equal" (different elts)
+    (with-current-buffer (get-buffer-create "#chan")
+      (erc-mode)
+      (setq erc-network 'foonet
+            erc-server-current-nick "tester"
+            erc-networks--id (erc-networks--id-create nil)
+            erc--target (erc--target-from-string "#chan")
+            erc-server-process foonet-proc))
+    (funcall check)
+    (erc-networks-tests--clean-bufs)))
+
+(ert-deftest erc-networks--reconcile-buffer-names--no-server-buf ()
+  (ert-info ("Existing #chan buffer respected")
+    (erc-tests--prep-erc-networks--reconcile-buffer-names--no-srv-buf
+     (lambda ()
+       (with-current-buffer "barnet"
+         (should (string= (erc-networks--reconcile-buffer-names
+                           (erc--target-from-string "#chan") erc-networks--id)
+                          "#chan@barnet")))
+       (ert-info ("Existing #chan buffer found and renamed")
+         (should (equal (erc-networks-tests--bufnames "#chan")
+                        '("#chan@foonet")))))))
+
+  (ert-info ("Existing #chan buffer")
+    (erc-tests--prep-erc-networks--reconcile-buffer-names--no-srv-buf
+     (lambda ()
+       (with-current-buffer (get-buffer-create "foonet")
+         (erc-mode)
+         (setq erc-network 'foonet
+               erc-server-current-nick "tester"
+               erc-networks--id (erc-networks--id-create nil)
+               erc-server-process (erc-networks-tests--create-dead-proc))
+         (should (string= (erc-networks--reconcile-buffer-names
+                           (erc--target-from-string "#chan") erc-networks--id)
+                          "#chan")))
+       (ert-info ("Nothing renamed")
+         (should (equal (erc-networks-tests--bufnames "#chan") '("#chan")))))))
+
+  (ert-info ("Existing #chan@foonet and #chan@barnet buffers")
+    (erc-tests--prep-erc-networks--reconcile-buffer-names--no-srv-buf
+     (lambda ()
+       (with-current-buffer "#chan"
+         (rename-buffer "#chan@foonet"))
+       (should-not (get-buffer "#chan@barnet"))
+       (with-current-buffer (get-buffer-create "#chan@barnet")
+         (erc-mode)
+         (setq erc--target (erc--target-from-string "#chan")
+               erc-server-process (buffer-local-value 'erc-server-process
+                                                      (get-buffer "barnet"))
+               erc-networks--id (erc-networks--id-create nil)))
+       (with-current-buffer (get-buffer-create "foonet")
+         (erc-mode)
+         (setq erc-network 'foonet
+               erc-server-current-nick "tester"
+               erc-server-process (erc-networks-tests--create-live-proc)
+               erc-networks--id (erc-networks--id-create nil))
+         (set-process-query-on-exit-flag erc-server-process nil)
+         (should (string= (erc-networks--reconcile-buffer-names
+                           (erc--target-from-string "#chan") erc-networks--id)
+                          "#chan@foonet")))
+       (ert-info ("Nothing renamed")
+         (should (equal (erc-networks-tests--bufnames "#chan")
+                        '("#chan@barnet" "#chan@foonet"))))))))
+
+(defun erc-tests--prep-erc-networks--reconcile-buffer-names--no-srv-buf-given
+    (check)
+  (let ((oofnet-proc (with-temp-buffer
+                       (erc-networks-tests--create-dead-proc))))
+
+    (with-current-buffer (get-buffer-create "rabnet")
+      (erc-mode)
+      ;; Again, given name preempts network lookup (unrealistic but
+      ;; highlights priorities)
+      (setq erc-networks--id (erc-networks--id-create 'rabnet)
+            erc-network 'barnet
+            erc-server-current-nick "tester"
+            erc-server-process (erc-networks-tests--create-dead-proc)))
+
+    ;; Identity is not "qual-equal" to above
+    (with-current-buffer (get-buffer-create "#chan")
+      (erc-mode)
+      (setq erc-networks--id (erc-networks--id-create 'oofnet)
+            erc-network 'foonet
+            erc--target (erc--target-from-string "#chan")
+            erc-server-process oofnet-proc))
+    (funcall check)
+    (erc-networks-tests--clean-bufs)))
+
+(ert-deftest erc-networks--reconcile-buffer-names--no-server-buf-given ()
+
+  (ert-info ("Existing #chan buffer respected")
+    (erc-tests--prep-erc-networks--reconcile-buffer-names--no-srv-buf-given
+     (lambda ()
+       (with-current-buffer "rabnet"
+         (should (string= (erc-networks--reconcile-buffer-names
+                           (erc--target-from-string "#chan") erc-networks--id)
+                          "#chan@rabnet")))
+
+       (ert-info ("Existing #chan buffer found and renamed")
+         (should (equal (erc-networks-tests--bufnames "#chan")
+                        '("#chan@oofnet")))))))
+
+  (ert-info ("Existing #chan@oofnet and #chan@rabnet buffers")
+    (erc-tests--prep-erc-networks--reconcile-buffer-names--no-srv-buf-given
+     (lambda ()
+       ;; #chan has already been uniquified (but not grown)
+       (with-current-buffer "#chan" (rename-buffer "#chan@oofnet"))
+       (should-not (get-buffer "#chan@rabnet"))
+
+       (with-current-buffer (get-buffer-create "#chan@rabnet")
+         (erc-mode)
+         (setq erc--target (erc--target-from-string "#chan")
+               erc-server-process (buffer-local-value 'erc-server-process
+                                                      (get-buffer "rabnet"))
+               erc-networks--id (buffer-local-value 'erc-networks--id
+                                                    (get-buffer "rabnet"))))
+
+       (with-current-buffer (get-buffer-create "oofnet")
+         (erc-mode)
+         (setq erc-network 'oofnet
+               erc-server-current-nick "tester"
+               erc-server-process (erc-networks-tests--create-live-proc)
+               erc-networks--id (erc-networks--id-create 'oofnet)) ; given
+         (set-process-query-on-exit-flag erc-server-process nil)
+         (should (string= (erc-networks--reconcile-buffer-names
+                           (erc--target-from-string "#chan") erc-networks--id)
+                          "#chan@oofnet")))
+
+       (ert-info ("Nothing renamed")
+         (should (equal (erc-networks-tests--bufnames "#chan")
+                        '("#chan@oofnet" "#chan@rabnet"))))))))
+
+;; This shows a corner case where a user explicitly assigns a "given"
+;; ID via `erc-tls' but later connects again without one.  It would
+;; actually probably be better if the given identity were to win and
+;; the derived one got an <n>-suffix.
+;;
+;; If we just compared net identities, the two would match, but they
+;; don't here because one has a given name and the other a
+;; discovered/assembled one; so they are *not* qual-equal.
+(ert-deftest erc-networks--reconcile-buffer-names--no-srv-buf-given-mismatch ()
+  ;; Existing #chan buffer *not* respected
+  (erc-tests--prep-erc-networks--reconcile-buffer-names--no-srv-buf-given
+   (lambda ()
+     (with-current-buffer (get-buffer-create "oofnet")
+       (erc-mode)
+       (setq erc-network 'oofnet
+             erc-server-current-nick "tester"
+             erc-server-process (erc-networks-tests--create-dead-proc)
+             erc-networks--id (erc-networks--id-create nil)) ; derived
+       (should (string= (erc-networks--reconcile-buffer-names
+                         (erc--target-from-string "#chan") erc-networks--id)
+                        "#chan@oofnet")))
+
+     (ert-info ("Collision renamed but not grown (because it's a given)")
+       ;; Original chan uniquified and moved out of the way
+       (should (equal (erc-networks-tests--bufnames "#chan")
+                      '("#chan@oofnet<2>")))))))
+
+(defun erc-tests--prep-erc-networks--reconcile-buffer-names--multi-net (check)
+
+  (with-current-buffer (get-buffer-create "foonet")
+    (erc-mode)
+    (setq erc-network 'foonet
+          erc-server-current-nick "tester"
+          erc-server-process (erc-networks-tests--create-dead-proc)
+          erc-networks--id (erc-networks--id-create nil))) ; derived
+
+  (with-current-buffer (get-buffer-create "barnet")
+    (erc-mode)
+    (setq erc-network 'barnet
+          erc-server-current-nick "tester"
+          erc-server-process (erc-networks-tests--create-dead-proc)
+          erc-networks--id (erc-networks--id-create nil))) ; derived
+
+  (with-current-buffer
+      (get-buffer-create (elt ["#chan" "#chan@foonet"] (random 2)))
+    (erc-mode)
+    (setq erc--target (erc--target-from-string "#chan"))
+    (cl-multiple-value-setq (erc-server-process erc-networks--id)
+      (with-current-buffer "foonet"
+        (list erc-server-process erc-networks--id))))
+
+  (with-current-buffer (get-buffer-create "#chan@barnet")
+    (erc-mode)
+    (setq erc--target (erc--target-from-string "#chan"))
+    (cl-multiple-value-setq (erc-server-process erc-networks--id)
+      (with-current-buffer "barnet"
+        (list erc-server-process erc-networks--id))))
+
+  (funcall check)
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks--reconcile-buffer-names--multi-net ()
+  (ert-info ("Same network rename")
+    (erc-tests--prep-erc-networks--reconcile-buffer-names--multi-net
+     (lambda ()
+       (with-current-buffer "foonet"
+         (let ((result (erc-networks--reconcile-buffer-names
+                        (erc--target-from-string "#chan") erc-networks--id)))
+           (should (string= result "#chan@foonet"))))
+
+       (should (equal (erc-networks-tests--bufnames "#chan")
+                      '("#chan@barnet" "#chan@foonet"))))))
+
+  (ert-info ("Same network keep name")
+    (erc-tests--prep-erc-networks--reconcile-buffer-names--multi-net
+     (lambda ()
+       (with-current-buffer "barnet"
+         (let ((result (erc-networks--reconcile-buffer-names
+                        (erc--target-from-string "#chan") erc-networks--id)))
+           (should (string= result "#chan@barnet"))))
+
+       (should (equal (erc-networks-tests--bufnames "#chan")
+                      '("#chan@barnet" "#chan@foonet")))))))
+
+(defun erc-tests--prep-erc-networks--reconcile-buffer-names--multi-net-given
+    (check)
+
+  (with-current-buffer (get-buffer-create "oofnet")
+    (erc-mode)
+    (setq erc-network 'foonet
+          erc-server-current-nick "tester"
+          erc-networks--id (erc-networks--id-create 'oofnet) ; one given
+          erc-server-process (erc-networks-tests--create-dead-proc)))
+
+  (with-current-buffer (get-buffer-create "rabnet")
+    (erc-mode)
+    (setq erc-network 'barnet
+          erc-server-current-nick "tester"
+          erc-networks--id (erc-networks--id-create 'rabnet) ; another given
+          erc-server-process (erc-networks-tests--create-dead-proc)))
+
+  (with-current-buffer (get-buffer-create (elt ["chan" "#chan@oofnet"]
+                                               (random 2)))
+    (erc-mode)
+    (setq erc--target (erc--target-from-string "#chan"))
+    (cl-multiple-value-setq (erc-server-process erc-networks--id)
+      (with-current-buffer "oofnet"
+        (list erc-server-process erc-networks--id))))
+
+  (with-current-buffer (get-buffer-create "#chan@barnet")
+    (erc-mode)
+    (setq erc--target (erc--target-from-string "#chan"))
+    (cl-multiple-value-setq (erc-server-process erc-networks--id)
+      (with-current-buffer "rabnet"
+        (list erc-server-process erc-networks--id))))
+
+  (funcall check)
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks--reconcile-buffer-names--multi-net-given ()
+  (ert-info ("Same network rename")
+    (erc-tests--prep-erc-networks--reconcile-buffer-names--multi-net-given
+     (lambda ()
+       (with-current-buffer "oofnet"
+         (let ((result (erc-networks--reconcile-buffer-names
+                        (erc--target-from-string "#chan") erc-networks--id)))
+           (should (string= result "#chan@oofnet"))))
+
+       (should (equal (erc-networks-tests--bufnames "#chan")
+                      '("#chan@oofnet" "#chan@rabnet"))))))
+
+  (ert-info ("Same network keep name")
+    (erc-tests--prep-erc-networks--reconcile-buffer-names--multi-net-given
+     (lambda ()
+       (with-current-buffer "rabnet"
+         (let ((result (erc-networks--reconcile-buffer-names
+                        (erc--target-from-string "#chan") erc-networks--id)))
+           (should (string= result "#chan@rabnet"))))
+
+       (should (equal (erc-networks-tests--bufnames "#chan")
+                      '("#chan@oofnet" "#chan@rabnet")))))))
+
+(defun erc-tests--prep-erc-networks--reconcile-buffer-names--multi-net-mixed
+    (check)
+
+  (with-current-buffer (get-buffer-create "foonet")
+    (erc-mode)
+    (setq erc-network 'foonet
+          erc-server-current-nick "tester"
+          erc-networks--id (erc-networks--id-create nil) ; one derived
+          erc-server-process (erc-networks-tests--create-dead-proc)))
+
+  (with-current-buffer (get-buffer-create "my-conn")
+    (erc-mode)
+    (setq erc-network 'barnet
+          erc-server-current-nick "tester"
+          erc-networks--id (erc-networks--id-create 'my-conn) ; one given
+          erc-server-process (erc-networks-tests--create-dead-proc)))
+
+  (with-current-buffer (get-buffer-create (elt ["#chan" "#chan@foonet"]
+                                               (random 2)))
+    (erc-mode)
+    (setq erc--target (erc--target-from-string "#chan"))
+    (cl-multiple-value-setq (erc-server-process erc-networks--id)
+      (with-current-buffer "foonet"
+        (list erc-server-process erc-networks--id))))
+
+  (with-current-buffer (get-buffer-create "#chan@my-conn")
+    (erc-mode)
+    (setq erc--target (erc--target-from-string "#chan"))
+    (cl-multiple-value-setq (erc-server-process erc-networks--id)
+      (with-current-buffer "my-conn"
+        (list erc-server-process erc-networks--id))))
+
+  (funcall check)
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks--reconcile-buffer-names--multi-net-existing ()
+
+  (ert-info ("Buf name derived from network")
+    (erc-tests--prep-erc-networks--reconcile-buffer-names--multi-net-mixed
+     (lambda ()
+       (with-current-buffer "foonet"
+         (let ((result (erc-networks--reconcile-buffer-names
+                        (erc--target-from-string "#chan") erc-networks--id)))
+           (should (string= result "#chan@foonet"))))
+
+       (should (equal (erc-networks-tests--bufnames "#chan")
+                      '("#chan@foonet" "#chan@my-conn"))))))
+
+  (ert-info ("Buf name given")
+    (erc-tests--prep-erc-networks--reconcile-buffer-names--multi-net-mixed
+     (lambda ()
+       (with-current-buffer "my-conn"
+         (let ((result (erc-networks--reconcile-buffer-names
+                        (erc--target-from-string "#chan") erc-networks--id)))
+           (should (string= result "#chan@my-conn"))))
+
+       (should (equal (erc-networks-tests--bufnames "#chan")
+                      '("#chan@foonet" "#chan@my-conn")))))))
+
+(ert-deftest erc-networks--reconcile-buffer-names--multi-net-suffixed ()
+  ;; Two networks, same channel.  One network has two connections.
+  ;; When the same channel is joined on the latter under a different
+  ;; nick, all buffer names involving that network are suffixed with
+  ;; the network identity.
+
+  (with-current-buffer (get-buffer-create "foonet/bob")
+    (erc-mode)
+    (setq erc-network 'foonet
+          erc-server-current-nick "bob"
+          erc-networks--id (make-erc-networks--id-qualifying
+                            :symbol 'foonet/bob
+                            :parts [foonet "bob"]
+                            :len 2)
+          erc-server-process (erc-networks-tests--create-live-proc)))
+
+  (with-current-buffer (get-buffer-create
+                        (elt ["#chan@foonet" "#chan@foonet/bob"] (random 2)))
+    (erc-mode)
+    (setq erc--target (erc--target-from-string "#chan")
+          erc-server-process (buffer-local-value 'erc-server-process
+                                                 (get-buffer "foonet/bob"))
+          erc-networks--id (buffer-local-value 'erc-networks--id
+                                               (get-buffer "foonet/bob"))))
+
+  (with-current-buffer (get-buffer-create "barnet")
+    (erc-mode)
+    (setq erc-network 'barnet
+          erc-server-current-nick (elt ["alice" "bob"] (random 2))
+          erc-networks--id (erc-networks--id-create 'barnet)
+          erc-server-process (erc-networks-tests--create-live-proc)))
+
+  (with-current-buffer (get-buffer-create "#chan@barnet")
+    (erc-mode)
+    (setq erc--target (erc--target-from-string "#chan")
+          erc-server-process (buffer-local-value 'erc-server-process
+                                                 (get-buffer "barnet"))
+          erc-networks--id (buffer-local-value 'erc-networks--id
+                                               (get-buffer "barnet"))))
+
+  (with-current-buffer (get-buffer-create "foonet/alice")
+    (erc-mode)
+    (setq erc-network 'foonet
+          erc-server-current-nick "alice"
+          erc-networks--id (make-erc-networks--id-qualifying
+                            :symbol 'foonet/alice
+                            :parts [foonet "alice"]
+                            :len 2)
+          erc-server-process (erc-networks-tests--create-live-proc)))
+
+  (with-current-buffer "foonet/alice"
+    (let ((result (erc-networks--reconcile-buffer-names
+                   (erc--target-from-string "#chan") erc-networks--id)))
+      (should (string= result "#chan@foonet/alice"))))
+
+  (should (equal (erc-networks-tests--bufnames "#chan")
+                 '("#chan@barnet" "#chan@foonet/bob")))
+
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks--reconcile-buffer-names--local ()
+  (with-current-buffer (get-buffer-create "DALnet")
+    (erc-mode)
+    (setq erc-network 'DALnet
+          erc-server-announced-name "elysium.ga.us.dal.net"
+          erc-server-process (erc-networks-tests--create-dead-proc)
+          erc--isupport-params (make-hash-table)
+          erc-networks--id (erc-networks--id-create nil))
+    (puthash 'CHANTYPES '("&#") erc--isupport-params))
+
+  (ert-info ("Local chan buffer from older, disconnected identity")
+    (with-current-buffer (get-buffer-create "&chan")
+      (erc-mode)
+      ;; Cheat here because localp is determined on identity init
+      (setq erc--target (with-current-buffer "DALnet"
+                          (erc--target-from-string "&chan"))
+            erc-network 'DALnet
+            erc-server-announced-name "twisted.ma.us.dal.net"
+            erc-server-process (erc-networks-tests--create-dead-proc)
+            erc-networks--id (erc-networks--id-create nil))))
+
+  (ert-info ("Local channels renamed using network server names")
+    (with-current-buffer "DALnet"
+      (let ((result (erc-networks--reconcile-buffer-names
+                     (erc--target-from-string "&chan") erc-networks--id)))
+        (should (string= result "&chan@elysium.ga.us.dal.net")))))
+
+  (should (get-buffer "&chan@twisted.ma.us.dal.net"))
+  (should-not (get-buffer "&chan"))
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks--set-name ()
+  (with-current-buffer (get-buffer-create "localhost:6667")
+    (let (erc-server-announced-name
+          (erc--isupport-params (make-hash-table))
+          erc-network
+          calls)
+      (erc-mode)
+
+      (cl-letf (((symbol-function 'erc-display-line)
+                 (lambda (&rest r) (push r calls))))
+
+        (ert-info ("Signals when `erc-server-announced-name' unset")
+          (should-error (erc-networks--set-name nil (make-erc-response)))
+          (should-not calls))
+
+        (ert-info ("Signals when table empty and NETWORK param unset")
+          (setq erc-server-announced-name "irc.fake.gnu.org")
+          (let ((err (should-error (erc-networks--set-name
+                                    nil (make-erc-response)))))
+            (should (string-match-p "failed" (cadr err)))
+            (should (eq (car err) 'error)))
+          (should (string-match-p (rx "*** Failed") (car (pop calls)))))))
+
+    (erc-networks-tests--clean-bufs)))
+
+(ert-deftest erc-networks--ensure-announced ()
+  (with-current-buffer (get-buffer-create "localhost:6667")
+    (should (local-variable-if-set-p 'erc-server-announced-name))
+    (let (erc-insert-modify-hook
+          (erc-server-process (erc-networks-tests--create-live-proc))
+          (parsed (make-erc-response
+                   :unparsed ":irc.barnet.org 422 tester :MOTD File is missing"
+                   :sender "irc.barnet.org"
+                   :command "422"
+                   :command-args '("tester" "MOTD File is missing")
+                   :contents "MOTD File is missing")))
+
+      (erc-mode) ; boilerplate displayable start (needs `erc-server-process')
+      (insert "\n\n")
+      (setq erc-input-marker (make-marker) erc-insert-marker (make-marker))
+      (set-marker erc-insert-marker (point-max))
+      (erc-display-prompt) ; boilerplate displayable end
+
+      (erc-networks--ensure-announced erc-server-process parsed)
+      (goto-char (point-min))
+      (search-forward "Failed")
+      (should (string= erc-server-announced-name "irc.barnet.org")))
+    (when noninteractive (kill-buffer))))
+
+(ert-deftest erc-networks--rename-server-buffer--no-existing--orphan ()
+  (with-current-buffer (get-buffer-create "#chan")
+    (erc-mode)
+    (setq erc-network 'FooNet
+          erc-server-current-nick "tester"
+          erc--target (erc--target-from-string "#chan")
+          erc-networks--id (erc-networks--id-create nil)))
+
+  (with-current-buffer (get-buffer-create "irc.foonet.org")
+    (erc-mode)
+    (setq erc-network 'FooNet
+          erc-server-current-nick "tester"
+          erc-server-process (erc-networks-tests--create-live-proc)
+          erc-networks--id (erc-networks--id-create nil))
+    (should-not (erc-networks--rename-server-buffer erc-server-process))
+    (should (string= (buffer-name) "FooNet")))
+
+  (ert-info ("Channel buffer reassociated")
+    (erc-server-process-alive "#chan")
+    (with-current-buffer "#chan"
+      (should erc-server-connected)
+      (erc-with-server-buffer
+        (should (string= (buffer-name) "FooNet")))))
+
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks--rename-server-buffer--existing--reuse ()
+  (let* ((old-buf (get-buffer-create "FooNet"))
+         (old-proc (erc-networks-tests--create-dead-proc old-buf)))
+
+    (with-current-buffer old-buf
+      (erc-mode)
+      (insert "*** Old buf")
+      (setq erc-network 'FooNet
+            erc-server-current-nick "tester"
+            erc-insert-marker (set-marker (make-marker) (point-max))
+            erc-server-process old-proc
+            erc-networks--id (erc-networks--id-create nil)))
+
+    (with-current-buffer (get-buffer-create "#chan")
+      (erc-mode)
+      (setq erc-network 'FooNet
+            erc-server-process old-proc
+            erc-networks--id (erc-networks--id-create nil)
+            erc--target (erc--target-from-string "#chan")))
+
+    (ert-info ("New buffer steals name, content")
+      (with-current-buffer (get-buffer-create "irc.foonet.org")
+        (erc-mode)
+        (setq erc-network 'FooNet
+              erc-server-current-nick "tester"
+              erc-server-process (erc-networks-tests--create-live-proc)
+              erc-networks--id (erc-networks--id-create nil))
+        (should-not (erc-networks--rename-server-buffer erc-server-process))
+        (should (string= (buffer-name) "FooNet"))
+        (goto-char (point-min))
+        (should (search-forward "Old buf"))))
+
+    (ert-info ("Channel buffer reassociated")
+      (erc-server-process-alive "#chan")
+      (with-current-buffer "#chan"
+        (should erc-server-connected)
+        (should-not (eq erc-server-process old-proc))
+        (erc-with-server-buffer
+          (should (string= (buffer-name) "FooNet")))))
+
+    (ert-info ("Original buffer killed off")
+      (should-not (buffer-live-p old-buf))))
+
+  (erc-networks-tests--clean-bufs))
+
+;; This is for compatibility with pre-28.1 behavior.  Basically, we're
+;; trying to match the behavior bug for bug.  All buffers were always
+;; suffixed and never reassociated.  28.1 introduced a regression that
+;; reversed the latter, but we've reverted that.
+
+(ert-deftest erc-networks--rename-server-buffer--existing--noreuse ()
+  (with-suppressed-warnings ((obsolete erc-reuse-buffers))
+    (should erc-reuse-buffers) ; default
+    (let* ((old-buf (get-buffer-create "irc.foonet.org:6697/irc.foonet.org"))
+           (old-proc (erc-networks-tests--create-dead-proc old-buf))
+           erc-reuse-buffers)
+      (with-current-buffer old-buf
+        (erc-mode)
+        (insert "*** Old buf")
+        (setq erc-network 'FooNet
+              erc-server-current-nick "tester"
+              erc-insert-marker (set-marker (make-marker) (point-max))
+              erc-server-process old-proc
+              erc-networks--id (erc-networks--id-create nil)))
+      (with-current-buffer (get-buffer-create "#chan")
+        (erc-mode)
+        (setq erc-network 'FooNet
+              erc-server-process old-proc
+              erc-networks--id (buffer-local-value 'erc-networks--id old-buf)
+              erc--target (erc--target-from-string "#chan"))
+        (rename-buffer (erc-networks--construct-target-buffer-name erc--target)))
+
+      (ert-info ("Server buffer uniquely renamed")
+        (with-current-buffer
+            (get-buffer-create "irc.foonet.org:6697/irc.foonet.org<2>")
+          (erc-mode)
+          (setq erc-network 'FooNet
+                erc-server-current-nick "tester"
+                erc-server-process (erc-networks-tests--create-live-proc)
+                erc-networks--id (erc-networks--id-create nil))
+          (should-not (erc-networks--rename-server-buffer erc-server-process))
+          (should (string= (buffer-name)
+                           "irc.foonet.org:6697/irc.foonet.org<2>"))
+          (goto-char (point-min))
+          (should-not (search-forward "Old buf" nil t))))
+
+      (ert-info ("Channel buffer not reassociated")
+        (should-not
+         (erc-server-process-alive
+          (should (get-buffer "#chan/irc.foonet.org"))))
+        (with-current-buffer (get-buffer "#chan/irc.foonet.org")
+          (should-not erc-server-connected)
+          (should (eq erc-server-process old-proc))
+          (erc-with-server-buffer
+            (should (string= (buffer-name)
+                             "irc.foonet.org:6697/irc.foonet.org")))))
+
+      (ert-info ("Old buffer still around")
+        (should (buffer-live-p old-buf)))))
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks--rename-server-buffer--reconnecting ()
+  (let* ((old-buf (get-buffer-create "FooNet"))
+         (old-proc (erc-networks-tests--create-dead-proc old-buf)))
+
+    (with-current-buffer old-buf
+      (erc-mode)
+      (insert "*** Old buf")
+      (setq erc-network 'FooNet
+            erc-server-current-nick "tester"
+            erc-insert-marker (set-marker (make-marker) (point-max))
+            erc-server-process old-proc
+            erc-networks--id (erc-networks--id-create nil)))
+
+    (with-current-buffer (get-buffer-create "#chan")
+      (erc-mode)
+      (setq erc-network 'FooNet
+            erc-server-process old-proc
+            erc--target (erc--target-from-string "#chan")
+            erc-networks--id (erc-networks--id-create nil)))
+
+    (ert-info ("No new buffer")
+      (with-current-buffer old-buf
+        (setq erc-server-process (erc-networks-tests--create-live-proc))
+        (should-not (erc-networks--rename-server-buffer erc-server-process))
+        (should (string= (buffer-name) "FooNet"))
+        (goto-char (point-min))
+        (should (search-forward "Old buf"))))
+
+    (ert-info ("Channel buffer updated with live proc")
+      (erc-server-process-alive "#chan")
+      (with-current-buffer "#chan"
+        (should erc-server-connected)
+        (should-not (eq erc-server-process old-proc))
+        (erc-with-server-buffer
+          (should (string= (buffer-name) "FooNet"))))))
+
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks--rename-server-buffer--id ()
+  (let* ((old-buf (get-buffer-create "MySession"))
+         (old-proc (erc-networks-tests--create-dead-proc old-buf)))
+
+    (with-current-buffer old-buf
+      (erc-mode)
+      (insert "*** Old buf")
+      (setq erc-network 'FooNet
+            erc-networks--id (erc-networks--id-create 'MySession)
+            erc-insert-marker (set-marker (make-marker) (point-max))
+            erc-server-process old-proc))
+
+    (with-current-buffer (get-buffer-create "#chan")
+      (erc-mode)
+      (setq erc-network 'FooNet
+            erc-networks--id (erc-networks--id-create 'MySession)
+            erc-server-process old-proc
+            erc--target (erc--target-from-string "#chan")))
+
+    (ert-info ("No new buffer")
+      (with-current-buffer old-buf
+        (setq erc-server-process (erc-networks-tests--create-live-proc))
+        (should-not (erc-networks--rename-server-buffer erc-server-process))
+        (should (string= (buffer-name) "MySession"))
+        (goto-char (point-min))
+        (should (search-forward "Old buf"))))
+
+    (ert-info ("Channel buffer updated with live proc")
+      (erc-server-process-alive "#chan")
+      (with-current-buffer "#chan"
+        (should erc-server-connected)
+        (should-not (eq erc-server-process old-proc))
+        (erc-with-server-buffer
+          (should (string= (buffer-name) "MySession"))))))
+
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks--rename-server-buffer--existing--live ()
+  (let* (erc-kill-server-hook
+         erc-insert-modify-hook
+         (old-buf (get-buffer-create "FooNet"))
+         (old-proc (erc-networks-tests--create-live-proc old-buf))) ; live
+
+    (with-current-buffer old-buf
+      (erc-mode)
+      (insert "*** Old buf")
+      (setq erc-network 'FooNet
+            erc-server-current-nick "tester"
+            erc-insert-marker (set-marker (make-marker) (point-max))
+            erc-server-process old-proc
+            erc-networks--id (erc-networks--id-create nil))
+      (should (erc-server-process-alive)))
+
+    (with-current-buffer (get-buffer-create "#chan")
+      (erc-mode)
+      (setq erc-network 'FooNet
+            erc-server-process old-proc
+            erc-networks--id (erc-networks--id-create nil)
+            erc-server-connected t
+            erc--target (erc--target-from-string "#chan")))
+
+    (ert-info ("New buffer rejected, abandoned, not killed")
+      (with-current-buffer (get-buffer-create "irc.foonet.org")
+        (erc-mode)
+        (setq erc-network 'FooNet
+              erc-server-current-nick "tester"
+              erc-insert-marker (set-marker (make-marker) (point-max))
+              erc-server-process (erc-networks-tests--create-live-proc)
+              erc-networks--id (erc-networks--id-create nil))
+        (should-not (erc-networks--rename-server-buffer erc-server-process))
+        (should (eq erc-active-buffer old-buf))
+        (should-not (erc-server-process-alive))
+        (should (string= (buffer-name) "irc.foonet.org"))
+        (goto-char (point-min))
+        (search-forward "still connected")))
+
+    (ert-info ("Channel buffer updated with live proc")
+      (should (erc-server-process-alive "#chan"))
+      (with-current-buffer "#chan"
+        (should erc-server-connected)
+        (should (erc-server-buffer-live-p))
+        (should (eq erc-server-process old-proc))
+        (should (buffer-live-p (process-buffer erc-server-process)))
+        (with-current-buffer (process-buffer erc-server-process)
+          (should (eq (current-buffer) (get-buffer "FooNet")))
+          (should (eq (current-buffer) old-buf))))))
+
+  (should (get-buffer "FooNet"))
+  (should (get-buffer "irc.foonet.org"))
+
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks--rename-server-buffer--local-match ()
+  (let* ((old-buf (get-buffer-create "FooNet"))
+         (old-proc (erc-networks-tests--create-dead-proc old-buf)))
+
+    (with-current-buffer old-buf
+      (erc-mode)
+      (insert "*** Old buf")
+      (setq erc-network 'FooNet
+            erc-server-current-nick "tester"
+            erc-server-announced-name "us-east.foonet.org"
+            erc-insert-marker (set-marker (make-marker) (point-max))
+            erc-server-process old-proc
+            erc--isupport-params (make-hash-table)
+            erc-networks--id (erc-networks--id-create nil))
+      (puthash 'CHANTYPES '("&#") erc--isupport-params))
+
+    (with-current-buffer (get-buffer-create "&chan")
+      (erc-mode)
+      (setq erc-network 'FooNet
+            erc-server-process old-proc
+            erc-server-announced-name "us-east.foonet.org"
+            erc--target (erc--target-from-string "&chan")
+            erc-networks--id (erc-networks--id-create nil)))
+
+    (ert-info ("New server buffer steals name, content")
+      (with-current-buffer (get-buffer-create "irc.foonet.org")
+        (erc-mode)
+        (setq erc-network 'FooNet
+              erc-server-current-nick "tester"
+              erc-server-announced-name "us-east.foonet.org"
+              erc-server-process (erc-networks-tests--create-live-proc)
+              erc--isupport-params (make-hash-table)
+              erc-networks--id (erc-networks--id-create nil))
+        (puthash 'CHANTYPES '("&#") erc--isupport-params)
+        (should-not (erc-networks--rename-server-buffer erc-server-process))
+        (should (string= (buffer-name) "FooNet"))
+        (goto-char (point-min))
+        (should (search-forward "Old buf"))))
+
+    (ert-info ("Channel buffer reassociated when &local server matches")
+      (should (erc-server-process-alive "&chan"))
+      (with-current-buffer "&chan"
+        (should erc-server-connected)
+        (should-not (eq erc-server-process old-proc))
+        (erc-with-server-buffer
+          (should (string= (buffer-name) "FooNet")))))
+
+    (ert-info ("Original buffer killed off")
+      (should-not (buffer-live-p old-buf)))
+
+    (erc-networks-tests--clean-bufs)))
+
+(ert-deftest erc-networks--rename-server-buffer--local-nomatch ()
+  (let* ((old-buf (get-buffer-create "FooNet"))
+         (old-proc (erc-networks-tests--create-dead-proc old-buf)))
+
+    (with-current-buffer old-buf
+      (erc-mode)
+      (insert "*** Old buf")
+      (setq erc-network 'FooNet
+            erc-server-current-nick "tester"
+            erc-server-announced-name "us-west.foonet.org"
+            erc-insert-marker (set-marker (make-marker) (point-max))
+            erc-server-process old-proc
+            erc--isupport-params (make-hash-table)
+            erc-networks--id (erc-networks--id-create nil))
+      (puthash 'CHANTYPES '("&#") erc--isupport-params))
+
+    (with-current-buffer (get-buffer-create "&chan")
+      (erc-mode)
+      (setq erc-network 'FooNet
+            erc-server-process old-proc
+            erc-server-announced-name "us-west.foonet.org" ; west
+            erc--target (erc--target-from-string "&chan")
+            erc-networks--id (erc-networks--id-create nil)))
+
+    (ert-info ("New server buffer steals name, content")
+      (with-current-buffer (get-buffer-create "irc.foonet.org")
+        (erc-mode)
+        (setq erc-network 'FooNet
+              erc-server-current-nick "tester"
+              erc-server-announced-name "us-east.foonet.org" ; east
+              erc-server-process (erc-networks-tests--create-live-proc)
+              erc--isupport-params (make-hash-table)
+              erc-networks--id (erc-networks--id-create nil))
+
+        (puthash 'CHANTYPES '("&#") erc--isupport-params)
+        (should-not (erc-networks--rename-server-buffer erc-server-process))
+        (should (string= (buffer-name) "FooNet"))
+        (goto-char (point-min))
+        (should (search-forward "Old buf"))))
+
+    (ert-info ("Channel buffer now orphaned even though network matches")
+      (should-not (erc-server-process-alive "&chan"))
+      (with-current-buffer "&chan"
+        (should-not erc-server-connected)
+        (should (eq erc-server-process old-proc))
+        (erc-with-server-buffer
+          (should (string= (buffer-name) "FooNet")))))
+
+    (ert-info ("Original buffer killed off")
+      (should-not (buffer-live-p old-buf)))
+
+    (erc-networks-tests--clean-bufs)))
+
+(ert-deftest erc-networks--update-server-identity--double-existing ()
+  (with-temp-buffer
+    (erc-mode)
+    (setq erc-networks--id (make-erc-networks--id-qualifying
+                            :parts [foonet "bob"] :len 1))
+
+    (with-current-buffer (get-buffer-create "#chan@foonet/bob")
+      (erc-mode)
+      (setq erc-networks--id (make-erc-networks--id-qualifying
+                              :parts [foonet "bob"] :len 2)))
+    (with-current-buffer (get-buffer-create "foonet/alice")
+      (erc-mode)
+      (setq erc-networks--id
+            (make-erc-networks--id-qualifying :parts [foonet "alice"] :len 2)))
+
+    (ert-info ("Adopt equivalent identity")
+      (should (eq (erc-networks--update-server-identity)
+                  (buffer-local-value 'erc-networks--id
+                                      (get-buffer "#chan@foonet/bob")))))
+
+    (ert-info ("Ignore non-matches")
+      (should-not (erc-networks--update-server-identity))
+      (should (eq erc-networks--id
+                  (buffer-local-value 'erc-networks--id
+                                      (get-buffer "#chan@foonet/bob"))))))
+
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks--update-server-identity--double-new ()
+  (with-temp-buffer
+    (erc-mode)
+    (setq erc-networks--id (make-erc-networks--id-qualifying
+                            :parts [foonet "bob"] :len 1))
+
+    (with-current-buffer (get-buffer-create "foonet/alice")
+      (erc-mode)
+      (setq erc-networks--id
+            (make-erc-networks--id-qualifying :parts [foonet "alice"] :len 2)))
+    (with-current-buffer (get-buffer-create "#chan@foonet/alice")
+      (erc-mode)
+      (setq erc-networks--id (buffer-local-value 'erc-networks--id
+                                                 (get-buffer "foonet/alice"))))
+
+    (ert-info ("Evolve identity to prevent ambiguity")
+      (should-not (erc-networks--update-server-identity))
+      (should (= (erc-networks--id-qualifying-len erc-networks--id) 2))
+      (should (eq (erc-networks--id-symbol erc-networks--id) 'foonet/bob))))
+
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks--update-server-identity--double-bounded ()
+  (with-temp-buffer
+    (erc-mode)
+    (setq erc-networks--id (make-erc-networks--id-qualifying
+                            :parts [foonet "bob"] :len 1))
+
+    (with-current-buffer (get-buffer-create "foonet/alice/home")
+      (erc-mode)
+      (setq erc-networks--id (make-erc-networks--id-qualifying
+                              :parts [foonet "alice" home] :len 3)))
+    (with-current-buffer (get-buffer-create "#chan@foonet/alice/home")
+      (erc-mode)
+      (setq erc-networks--id
+            (buffer-local-value 'erc-networks--id
+                                (get-buffer "foonet/alice/home"))))
+
+    (ert-info ("Evolve identity to prevent ambiguity")
+      (should-not (erc-networks--update-server-identity))
+      (should (= (erc-networks--id-qualifying-len erc-networks--id) 2))
+      (should (eq (erc-networks--id-symbol erc-networks--id) 'foonet/bob))))
+
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks--update-server-identity--double-even ()
+  (with-temp-buffer
+    (erc-mode)
+    (setq erc-networks--id
+          (make-erc-networks--id-qualifying :parts [foonet "bob"] :len 1))
+
+    (with-current-buffer (get-buffer-create "foonet")
+      (erc-mode)
+      (setq erc-networks--id
+            (make-erc-networks--id-qualifying :parts [foonet "alice"] :len 1)))
+    (with-current-buffer (get-buffer-create "#chan")
+      (erc-mode)
+      (setq erc--target (erc--target-from-string "#chan")
+            erc-networks--id (buffer-local-value 'erc-networks--id
+                                                 (get-buffer "foonet"))))
+
+    (ert-info ("Evolve identity to prevent ambiguity")
+      (should-not (erc-networks--update-server-identity))
+      (should (= (erc-networks--id-qualifying-len erc-networks--id) 2))
+      (should (eq (erc-networks--id-symbol erc-networks--id) 'foonet/bob)))
+
+    (ert-info ("Collision renamed")
+      (with-current-buffer "foonet/alice"
+        (should (eq (erc-networks--id-symbol erc-networks--id) 'foonet/alice)))
+
+      (with-current-buffer "#chan@foonet/alice"
+        (should (eq (erc-networks--id-symbol erc-networks--id)
+                    'foonet/alice)))))
+
+  (erc-networks-tests--clean-bufs))
+
+(ert-deftest erc-networks--update-server-identity--triple-new ()
+  (with-temp-buffer
+    (erc-mode)
+    (setq erc-networks--id
+          (make-erc-networks--id-qualifying :parts [foonet "bob" home] :len 1))
+
+    (with-current-buffer (get-buffer-create "foonet/bob/office")
+      (erc-mode)
+      (setq erc-networks--id
+            (make-erc-networks--id-qualifying :parts [foonet "bob" office]
+                                              :len 3)))
+    (with-current-buffer (get-buffer-create "#chan@foonet/bob/office")
+      (erc-mode)
+      (setq erc-networks--id
+            (buffer-local-value 'erc-networks--id
+                                (get-buffer "foonet/bob/office"))))
+
+    (ert-info ("Extend our identity's canonical ID so that it's unique")
+      (should-not (erc-networks--update-server-identity))
+      (should (= (erc-networks--id-qualifying-len erc-networks--id) 3))))
+
+  (erc-networks-tests--clean-bufs))
+
+;;; erc-networks-tests.el ends here