--- /dev/null
+;;; cal-julian-tests.el --- tests for calendar/cal-julian.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 'cal-julian)
+
+(ert-deftest cal-julian-test-to-absolute ()
+ (should (equal (calendar-gregorian-from-absolute
+ (calendar-julian-to-absolute
+ '(10 25 1917)))
+ '(11 7 1917))))
+
+(ert-deftest cal-julian-test-from-absolute ()
+ (should (equal (calendar-julian-from-absolute
+ (calendar-absolute-from-gregorian
+ '(11 7 1917)))
+ '(10 25 1917))))
+
+(ert-deftest cal-julian-test-date-string ()
+ (should (equal (let ((calendar-date-display-form calendar-iso-date-display-form))
+ (calendar-julian-date-string '(11 7 1917)))
+ "1917-10-25")))
+
+(defmacro with-cal-julian-test (&rest body)
+ `(save-window-excursion
+ (unwind-protect
+ (progn
+ (calendar)
+ ,@body)
+ (kill-buffer "*Calendar*"))))
+
+(ert-deftest cal-julian-test-goto-date ()
+ (with-cal-julian-test
+ (calendar-julian-goto-date '(10 25 1917))
+ (should (looking-at "7"))))
+
+(ert-deftest cal-julian-test-astro-to-and-from-absolute ()
+ (should (= (+ (calendar-astro-to-absolute 0.0)
+ (calendar-astro-from-absolute 0.0))
+ 0.0)))
+
+(ert-deftest cal-julian-calendar-astro-date-string ()
+ (should (equal (calendar-astro-date-string '(10 25 1917)) "2421527")))
+
+(ert-deftest calendar-astro-goto-day-number ()
+ (with-cal-julian-test
+ (calendar-astro-goto-day-number 2421527)
+ (backward-char)
+ (should (looking-at "25"))))
+
+(provide 'cal-julian-tests)
+;;; cal-julian-tests.el ends here