;;; ert-x.el --- Staging area for experimental extensions to ERT -*- lexical-binding: t -*-
-;; Copyright (C) 2008, 2010-2015 Free Software Foundation, Inc.
+;; Copyright (C) 2008, 2010-2016 Free Software Foundation, Inc.
;; Author: Lennart Borgman (lennart O borgman A gmail O com)
;; Christian Ohler <ohler@gnu.org>
(kill-buffer clone)))))))
+(defmacro ert-with-function-mocked (name mock &rest body)
+ "Mocks function NAME with MOCK and run BODY.
+
+Once BODY finishes (be it normally by returning a value or
+abnormally by throwing or signalling), the old definition of
+function NAME is restored.
+
+BODY may further change the mock with `fset'.
+
+If MOCK is nil, the function NAME is mocked with a function
+`ert-fail'ing when called.
+
+For example:
+
+ ;; Regular use, function is mocked inside the BODY:
+ (should (eq 2 (+ 1 1)))
+ (ert-with-function-mocked ((+ (lambda (a b) (- a b))))
+ (should (eq 0 (+ 1 1))))
+ (should (eq 2 (+ 1 1)))
+
+ ;; Macro correctly recovers from a throw or signal:
+ (should
+ (catch 'done
+ (ert-with-function-mocked ((+ (lambda (a b) (- a b))))
+ (should (eq 0 (+ 1 1))))
+ (throw 'done t)))
+ (should (eq 2 (+ 1 1)))
+"
+ (declare (indent 2))
+ (let ((old-var (make-symbol "old-var"))
+ (mock-var (make-symbol "mock-var")))
+ `(let ((,old-var (symbol-function (quote ,name))) (,mock-var ,mock))
+ (fset (quote ,name)
+ (or ,mock-var (lambda (&rest _)
+ (ert-fail (concat "`" ,(symbol-name name)
+ "' unexpectedly called.")))))
+ (unwind-protect
+ (progn ,@body)
+ (fset (quote ,name) ,old-var)))))
+
(provide 'ert-x)
;;; ert-x.el ends here