Fix handling of ‘mouse-on-link-p’.

If ‘mouse-on-link-p’ returns a string or vector, the first element
is to be used as new event.  Translation to ‘mouse-2’ should only
happen if the return value is not a string or vector.  See
docstring of ‘mouse-on-link-p’ and Bug#23288.

* lisp/mouse.el (mouse--down-1-maybe-follows-link): Process return
value of ‘mouse-on-link-p’ according to documentation.

* test/lisp/mouse-tests.el (bug23288-use-return-value)
(bug23288-translate-to-mouse-2): Tests for Bug#23288.

1 files changed, 48 insertions, 0 deletions

diff --git a/test/lisp/mouse-tests.el b/test/lisp/mouse-tests.el
new file mode 100644
index 00000000000..21abf38798d
--- /dev/null
+++ b/test/lisp/mouse-tests.el
@@ -0,0 +1,48 @@
+;;; mouse-tests.el --- unit tests for mouse.el       -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2016  Free Software Foundation, Inc.
+
+;; Author: Philipp Stephani <phst@google.com>
+
+;; This program 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.
+
+;; This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; Unit tests for lisp/mouse.el.
+
+;;; Code:
+
+(ert-deftest bug23288-use-return-value ()
+  "If ‘mouse-on-link-p’ returns a string, its first character is
+used."
+  (cl-letf ((last-input-event '(down-mouse-1 nil 1))
+            (unread-command-events '((mouse-1 nil 1)))
+            (mouse-1-click-follows-link t)
+            (mouse-1-click-in-non-selected-windows t)
+            ((symbol-function 'mouse-on-link-p) (lambda (_pos) "abc")))
+    (should-not (mouse--down-1-maybe-follows-link))
+    (should (equal unread-command-events '(?a)))))
+
+(ert-deftest bug23288-translate-to-mouse-2 ()
+  "If ‘mouse-on-link-p’ doesn’t return a string or vector,
+translate ‘mouse-1’ events into ‘mouse-2’ events."
+  (cl-letf ((last-input-event '(down-mouse-1 nil 1))
+            (unread-command-events '((mouse-1 nil 1)))
+            (mouse-1-click-follows-link t)
+            (mouse-1-click-in-non-selected-windows t)
+            ((symbol-function 'mouse-on-link-p) (lambda (_pos) t)))
+    (should-not (mouse--down-1-maybe-follows-link))
+    (should (equal unread-command-events '((mouse-2 nil 1))))))
+
+;;; mouse-tests.el ends here