New library thunk.el

thunk.el is extracted from stream.el in ELPA, with additional tests.

* lisp/emacs-lisp/thunk.el: New file.
* test/automated/thunk-tests.el: New file.
* etc/NEWS: Add information about thunk.el

1 files changed, 55 insertions, 0 deletions

diff --git a/test/automated/thunk-tests.el b/test/automated/thunk-tests.el
new file mode 100644
index 00000000000..7abbd299ead
--- /dev/null
+++ b/test/automated/thunk-tests.el
@@ -0,0 +1,55 @@
+;;; thunk-tests.el --- Tests for thunk.el -*- lexical-binding: t -*-
+
+;; Copyright (C) 2015 Free Software Foundation, Inc.
+
+;; Author: Nicolas Petton <nicolas@petton.fr>
+;; Maintainer: emacs-devel@gnu.org
+
+;; 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 <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; Tests for thunk.el
+
+;;; Code:
+
+(require 'ert)
+(require 'thunk)
+
+(ert-deftest thunk-should-be-lazy ()
+  (let (x)
+    (thunk-delay (setq x t))
+    (should (null x))))
+
+(ert-deftest thunk-can-be-evaluated ()
+  (let* (x
+         (thunk (thunk-delay (setq x t))))
+    (should-not (thunk-evaluated-p thunk))
+    (should (null x))
+    (thunk-force thunk)
+    (should (thunk-evaluated-p thunk))
+    (should x)))
+
+(ert-deftest thunk-evaluation-is-cached ()
+  (let* ((x 0)
+        (thunk (thunk-delay (setq x (1+ x)))))
+    (thunk-force thunk)
+    (should (= x 1))
+    (thunk-force thunk)
+    (should (= x 1))))
+
+(provide 'thunk-tests)
+;;; thunk-tests.el ends here