Use lexical-binding in lunar.el and add tests

* lisp/calendar/lunar.el: Use lexical-binding.
(lunar-phases, diary-lunar-phases): Silence byte-compiler.
* test/lisp/calendar/lunar-tests.el: New file.

lisp/calendar/lunar.el

@@ -1,4 +1,4 @@
-;;; lunar.el --- calendar functions for phases of the moon
+;;; lunar.el --- calendar functions for phases of the moon  -*- lexical-binding:t -*-
 
 ;; Copyright (C) 1992-1993, 1995, 1997, 2001-2020 Free Software
 ;; Foundation, Inc.
@@ -255,6 +255,8 @@ use instead of point."
 If called with an optional prefix argument ARG, prompts for month and year.
 This function is suitable for execution in an init file."
   (interactive "P")
+  (with-suppressed-warnings ((lexical date))
+    (defvar date))
   (save-excursion
     (let* ((date (if arg (calendar-read-date t)
                    (calendar-current-date)))
@@ -262,18 +264,17 @@ This function is suitable for execution in an init file."
            (displayed-year (calendar-extract-year date)))
       (calendar-lunar-phases))))
 
-;; The function below is designed to be used in sexp diary entries,
-;; and may be present in users' diary files, so suppress the warning
-;; about this prefix-less dynamic variable.  It's called from
-;; `diary-list-sexp-entries', which binds the variable.
-(with-suppressed-warnings ((lexical date))
-  (defvar date))
-
 ;;;###diary-autoload
 (defun diary-lunar-phases (&optional mark)
   "Moon phases diary entry.
 An optional parameter MARK specifies a face or single-character string to
 use when highlighting the day in the calendar."
+  ;; This function is designed to be used in sexp diary entries, and
+  ;; may be present in users' diary files, so suppress the warning
+  ;; about this prefix-less dynamic variable.  It's called from
+  ;; `diary-list-sexp-entries', which binds the variable.
+  (with-suppressed-warnings ((lexical date))
+    (defvar date))
   (let* ((index (lunar-index date))
          (phase (lunar-phase index)))
     (while (calendar-date-compare phase (list date))

test/lisp/calendar/lunar-tests.el

@@ -0,0 +1,70 @@
+;;; lunar-tests.el --- tests for calendar/lunar.el  -*- lexical-binding:t -*-
+
+;; Copyright (C) 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/>.
+
+;;; Code:
+
+(require 'ert)
+(require 'lunar)
+
+(defmacro with-lunar-test (&rest body)
+  `(let ((calendar-latitude 40.1)
+         (calendar-longitude -88.2)
+         (calendar-location-name "Urbana, IL")
+         (calendar-time-zone -360)
+         (calendar-standard-time-zone-name "CST")
+         (calendar-time-display-form '(12-hours ":" minutes am-pm)))
+     ,@body))
+
+(ert-deftest lunar-test-phase ()
+  (with-lunar-test
+   (should (equal (lunar-phase 1)
+                  '((1 7 1900) "11:40pm" 1 "")))))
+
+(ert-deftest lunar-test-eclipse-check ()
+  (with-lunar-test
+   (should (equal (eclipse-check 1 1) "**  Eclipse **"))))
+
+(ert-deftest lunar-test-phase-list ()
+  (with-lunar-test
+   (should (equal  (lunar-phase-list 3 1871)
+                   '(((3 20 1871) "11:03pm" 0 "")
+                     ((3 29 1871) "1:46am" 1 "**  Eclipse **")
+                     ((4 5 1871) "9:20am" 2 "")
+                     ((4 12 1871) "12:57am" 3 "**  Eclipse possible **")
+                     ((4 19 1871) "2:06pm" 0 "")
+                     ((4 27 1871) "6:49pm" 1 "")
+                     ((5 4 1871) "5:57pm" 2 "")
+                     ((5 11 1871) "9:29am" 3 "")
+                     ((5 19 1871) "5:46am" 0 "")
+                     ((5 27 1871) "8:02am" 1 ""))))))
+
+(ert-deftest lunar-test-new-moon-time ()
+  (with-lunar-test
+   (should (= (round (lunar-new-moon-time 1))
+              2451580))))
+
+(ert-deftest lunar-test-new-moon-on-or-after ()
+  (with-lunar-test
+   (should (= (round (lunar-new-moon-on-or-after (calendar-absolute-from-gregorian '(5 5 1818))))
+              664525))))
+
+(provide 'lunar-tests)
+;;; lunar-tests.el ends here