; Make some ERC test fixtures a bit more courteous

* test/lisp/erc/erc-dcc-tests.el (erc-dcc-tests--pcomplete-common):
Only emit messages when interactive.
* test/lisp/erc/resources/erc-d/erc-d-tests.el
(erc-d-tests-with-server): Shadow `erc-after-connect' so
`erc-autojoin-channels' doesn't affect other tests.
test/lisp/erc/resources/erc-scenarios-common.el
(erc-scenarios-common--make-bindings): Shadow `erc-after-connect' here
as well.  Also require erc instead of erc-backend to silence some new
compiler warnings the cropped up after the creation of erc-common.el.

test/lisp/erc/erc-dcc-tests.el

@@ -167,7 +167,8 @@
 
 (defun erc-dcc-tests--pcomplete-common (test-fn)
   (with-current-buffer (get-buffer-create "*erc-dcc-do-GET-command*")
-    (let* ((proc (start-process "fake" (current-buffer) "sleep" "10"))
+    (let* ((inhibit-message noninteractive)
+           (proc (start-process "fake" (current-buffer) "sleep" "10"))
            (elt (list :nick "tester!~tester@fake.irc"
                       :type 'GET
                       :peer nil

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

@@ -562,6 +562,7 @@ DUMB-SERVER-VAR are bound accordingly in BODY."
           ;;
           (erc-server-flood-penalty 0.05)
           erc-autojoin-channels-alist
+          erc-after-connect
           erc-server-auto-reconnect)
      (should-not erc-d--slow-mo)
      (with-current-buffer "*erc-d-server*" (erc-d-t-search-for 4 "Starting"))

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

@@ -73,7 +73,7 @@
     (require 'erc-d-t)
     (require 'erc-d)))
 
-(require 'erc-backend)
+(require 'erc)
 
 (eval-when-compile (require 'erc-join)
                    (require 'erc-services))
@@ -125,6 +125,7 @@
       (erc-auth-source-parameters-join-function nil)
       (erc-autojoin-channels-alist nil)
       (erc-server-auto-reconnect nil)
+      (erc-after-connect nil)
       (erc-d-linger-secs 10)
       ,@bindings)))