Distinguish buttons from widgets (bug#34506)

* lisp/button.el (button-at):
* lisp/wid-edit.el (widget-at): Avoid returning a false positive
when looking for a button and finding a widget, or vice versa.
* test/lisp/button-tests.el:
* test/lisp/wid-edit-tests.el: New files.

2 files changed, 79 insertions, 0 deletions

diff --git a/test/lisp/button-tests.el b/test/lisp/button-tests.el
new file mode 100644
index 00000000000..d54a992ab89
--- /dev/null
+++ b/test/lisp/button-tests.el
@@ -0,0 +1,40 @@
+;;; button-tests.el --- tests for button.el -*- lexical-binding: t -*-
+
+;; Copyright (C) 2019 Free Software Foundation, Inc.
+
+;; 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 <https://www.gnu.org/licenses/>.
+
+;;; Code:
+
+(require 'ert)
+
+(ert-deftest button-at ()
+  "Test `button-at' behavior."
+  (with-temp-buffer
+    (should-not (button-at (point)))
+    (let ((button (insert-text-button "text button"))
+          (marker (button-at (1- (point)))))
+      (should (markerp marker))
+      (should (= (button-end button) (button-end marker) (point))))
+    (let ((button  (insert-button "overlay button"))
+          (overlay (button-at (1- (point)))))
+      (should (overlayp overlay))
+      (should (eq button overlay)))
+    ;; Buttons and widgets are incompatible (bug#34506).
+    (widget-create 'link "link widget")
+    (should-not (button-at (1- (point))))))
+
+;;; button-tests.el ends here
diff --git a/test/lisp/wid-edit-tests.el b/test/lisp/wid-edit-tests.el
new file mode 100644
index 00000000000..a4350e715ed
--- /dev/null
+++ b/test/lisp/wid-edit-tests.el
@@ -0,0 +1,39 @@
+;;; wid-edit-tests.el --- tests for wid-edit.el -*- lexical-binding: t -*-
+
+;; Copyright (C) 2019 Free Software Foundation, Inc.
+
+;; 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 <https://www.gnu.org/licenses/>.
+
+;;; Code:
+
+(require 'ert)
+(require 'wid-edit)
+
+(ert-deftest widget-at ()
+  "Test `widget-at' behavior."
+  (with-temp-buffer
+    (should-not (widget-at))
+    (let ((marco (widget-create 'link "link widget"))
+          (polo  (widget-at (1- (point)))))
+      (should (widgetp polo))
+      (should (eq marco polo)))
+    ;; Buttons and widgets are incompatible (bug#34506).
+    (insert-text-button "text button")
+    (should-not (widget-at (1- (point))))
+    (insert-button "overlay button")
+    (should-not (widget-at (1- (point))))))
+
+;;; wid-edit-tests.el ends here