Use lexical-binding in saveplace.el and add tests

* lisp/saveplace.el: Use lexical-binding.
(save-place-to-alist): Doc fix.
* test/lisp/saveplace-tests.el:
* test/lisp/saveplace-resources/saveplace: New files.

lisp/saveplace.el

@@ -1,4 +1,4 @@
-;;; saveplace.el --- automatically save place in files
+;;; saveplace.el --- automatically save place in files  -*- lexical-binding:t -*-
 
 ;; Copyright (C) 1993-1994, 2001-2020 Free Software Foundation, Inc.
 
@@ -42,7 +42,6 @@
   "Automatically save place in files."
   :group 'data)
 
-
 (defvar save-place-alist nil
   "Alist of saved places to go back to when revisiting files.
 Each element looks like (FILENAME . POSITION);
@@ -175,10 +174,11 @@ file:
 (declare-function dired-get-filename "dired" (&optional localp no-error-if-not-filep))
 
 (defun save-place-to-alist ()
-  ;; put filename and point in a cons box and then cons that onto the
-  ;; front of the save-place-alist, if save-place-mode is non-nil.
-  ;; Otherwise, just delete that file from the alist.
-  ;; first check to make sure alist has been loaded in from the master
+  "Add current buffer filename and position to `save-place-alist'.
+Put filename and point in a cons box and then cons that onto the
+front of the `save-place-alist', if `save-place-mode' is non-nil.
+Otherwise, just delete that file from the alist."
+  ;; First check to make sure alist has been loaded in from the master
   ;; file.  If not, do so, then feel free to modify the alist.  It
   ;; will be saved again when Emacs is killed.
   (or save-place-loaded (load-save-place-alist-from-file))

test/lisp/saveplace-resources/saveplace

@@ -0,0 +1,4 @@
+;;; -*- coding: utf-8 -*-
+(("/home/skangas/.emacs.d/cache/recentf" . 1306)
+ ("/home/skangas/wip/emacs/"
+  (dired-filename . "/home/skangas/wip/emacs/COPYING")))

test/lisp/saveplace-tests.el

@@ -0,0 +1,103 @@
+;;; saveplace-tests.el --- Tests for saveplace.el  -*- lexical-binding:t -*-
+
+;; Copyright (C) 2019-2020 Free Software Foundation, Inc.
+
+;; Author: Stefan Kangas <stefankangas@gmail.com>
+
+;; 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/>.
+
+;;; Commentary:
+
+(require 'ert)
+(require 'saveplace)
+
+(defvar saveplace-tests-dir
+  (file-truename
+   (expand-file-name "saveplace-resources"
+                     (file-name-directory (or load-file-name
+                                              buffer-file-name)))))
+
+(ert-deftest saveplace-test-save-place-to-alist/dir ()
+  (save-place-mode)
+  (let* ((save-place-alist nil)
+         (save-place-loaded t)
+         (loc saveplace-tests-dir))
+    (save-window-excursion
+      (dired loc)
+      (save-place-to-alist)
+      (should (equal save-place-alist
+                     `((,(concat loc "/")
+                        (dired-filename . ,(concat loc "/saveplace")))))))))
+
+(ert-deftest saveplace-test-save-place-to-alist/file ()
+  (save-place-mode)
+  (let* ((tmpfile (make-temp-file "emacs-test-saveplace-"))
+         (save-place-alist nil)
+         (save-place-loaded t)
+         (loc tmpfile)
+         (pos 4))
+    (unwind-protect
+        (save-window-excursion
+          (find-file loc)
+          (insert "abc") ; must insert something
+          (save-place-to-alist)
+          (should (equal save-place-alist (list (cons tmpfile pos)))))
+      (delete-file tmpfile))))
+
+(ert-deftest saveplace-test-forget-unreadable-files ()
+  (save-place-mode)
+  (let* ((save-place-loaded t)
+         (tmpfile (make-temp-file "emacs-test-saveplace-"))
+         (alist-orig (list (cons "/this/file/does/not/exist" 10)
+                           (cons tmpfile 1917)))
+         (save-place-alist alist-orig))
+    (unwind-protect
+        (progn
+          (save-place-forget-unreadable-files)
+          (should (equal save-place-alist (cdr alist-orig))))
+      (delete-file tmpfile))))
+
+(ert-deftest saveplace-test-place-alist-to-file ()
+  (save-place-mode)
+  (let* ((tmpfile (make-temp-file "emacs-test-saveplace-"))
+         (tmpfile2 (make-temp-file "emacs-test-saveplace-"))
+         (save-place-file tmpfile)
+         (save-place-alist (list (cons tmpfile2 99))))
+    (unwind-protect
+        (progn (save-place-alist-to-file)
+               (setq save-place-alist nil)
+               (save-window-excursion
+                 (find-file save-place-file)
+                 (unwind-protect
+                     (should (string-match tmpfile2 (buffer-string)))
+                   (kill-buffer))))
+      (delete-file tmpfile)
+      (delete-file tmpfile2))))
+
+(ert-deftest saveplace-test-load-alist-from-file ()
+  (save-place-mode)
+  (let ((save-place-loaded nil)
+        (save-place-file
+         (expand-file-name "saveplace" saveplace-tests-dir))
+        (save-place-alist nil))
+    (load-save-place-alist-from-file)
+    (should (equal save-place-alist
+                   '(("/home/skangas/.emacs.d/cache/recentf" . 1306)
+                     ("/home/skangas/wip/emacs/"
+                      (dired-filename . "/home/skangas/wip/emacs/COPYING")))))))
+
+(provide 'saveplace-tests)
+;;; saveplace-tests.el ends here