Make use of the `ert-with-function-mocked' macro

* test/lisp/calendar/icalendar-tests.el (icalendar--create-uid):
* test/lisp/vc/vc-bzr-tests.el (vc-bzr-test-bug9781): Use
`ert-with-function-mocked' instead of implementing the fragile
`unwind-protect' logic openly.

test/lisp/calendar/icalendar-tests.el

@@ -32,6 +32,7 @@
 ;;; Code:
 
 (require 'ert)
+(require 'ert-x)
 (require 'icalendar)
 
 ;; ======================================================================
@@ -58,23 +59,16 @@
 (ert-deftest icalendar--create-uid ()
   "Test for `icalendar--create-uid'."
   (let* ((icalendar-uid-format "xxx-%t-%c-%h-%u-%s")
-         t-ct
          (icalendar--uid-count 77)
          (entry-full "30.06.1964 07:01 blahblah")
          (hash (format "%d" (abs (sxhash entry-full))))
          (contents "DTSTART:19640630T070100\nblahblah")
-         (username (or user-login-name "UNKNOWN_USER"))
-         )
-    (fset 't-ct (symbol-function 'current-time))
-    (unwind-protect
-	(progn
-	  (fset 'current-time (lambda () '(1 2 3)))
-	  (should (= 77 icalendar--uid-count))
-	  (should (string=  (concat "xxx-123-77-" hash "-" username "-19640630")
-			    (icalendar--create-uid entry-full contents)))
-	  (should (= 78 icalendar--uid-count)))
-      ;; restore 'current-time
-      (fset 'current-time (symbol-function 't-ct)))
+         (username (or user-login-name "UNKNOWN_USER")))
+    (ert-with-function-mocked current-time (lambda () '(1 2 3))
+      (should (= 77 icalendar--uid-count))
+      (should (string=  (concat "xxx-123-77-" hash "-" username "-19640630")
+                        (icalendar--create-uid entry-full contents)))
+      (should (= 78 icalendar--uid-count)))
     (setq contents "blahblah")
     (setq icalendar-uid-format "yyy%syyy")
     (should (string=  (concat "yyyDTSTARTyyy")

test/lisp/vc/vc-bzr-tests.el

@@ -25,6 +25,7 @@
 ;;; Code:
 
 (require 'ert)
+(require 'ert-x)
 (require 'vc-bzr)
 (require 'vc-dir)
 
@@ -101,12 +102,8 @@
           (while (vc-dir-busy)
             (sit-for 0.1))
           (vc-dir-mark-all-files t)
-          (let ((f (symbol-function 'y-or-n-p)))
-            (unwind-protect
-                (progn
-                  (fset 'y-or-n-p (lambda (prompt) t))
-                  (vc-next-action nil))
-              (fset 'y-or-n-p f)))
+          (ert-with-function-mocked y-or-n-p (lambda (_) t)
+            (vc-next-action nil))
           (should (get-buffer "*vc-log*")))
       (delete-directory homedir t))))