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+;;; test-chime--today.el --- Tests for chime--today -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2024 Craig Jennings
+
+;; Author: Craig Jennings <c@cjennings.net>
+
+;; 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 chime--today function.
+;; Tests retrieving beginning of current day timestamp.
+
+;;; Code:
+
+;; Initialize package system for batch mode
+(when noninteractive
+  (package-initialize))
+
+(require 'ert)
+(require 'dash)
+(require 'alert)
+
+;; Load chime from parent directory
+(load (expand-file-name "../chime.el") nil t)
+
+;;; Setup and Teardown
+
+(defun test-chime--today-setup ()
+  "Setup test environment."
+  ;; No special setup needed
+  )
+
+(defun test-chime--today-teardown ()
+  "Teardown test environment."
+  ;; No special teardown needed
+  )
+
+;;; Normal Cases
+
+(ert-deftest test-chime--today-normal-returns-current-date ()
+  "Test that chime--today returns midnight of current day."
+  (test-chime--today-setup)
+  (unwind-protect
+      (let* ((now (encode-time 30 45 14 8 11 2025))  ; 2025-11-08 14:45:30
+             (expected (encode-time 0 0 0 8 11 2025))) ; 2025-11-08 00:00:00
+        (cl-letf (((symbol-function 'current-time) (lambda () now)))
+          (should (equal (chime--today) expected))))
+    (test-chime--today-teardown)))
+
+(ert-deftest test-chime--today-normal-truncates-time-component ()
+  "Test that chime--today zeros out hour/minute/second."
+  (test-chime--today-setup)
+  (unwind-protect
+      (let* ((now (encode-time 59 59 23 8 11 2025))  ; 2025-11-08 23:59:59
+             (result (cl-letf (((symbol-function 'current-time) (lambda () now)))
+                       (chime--today)))
+             (decoded (decode-time result)))
+        ;; Check that hour, minute, second are all 0
+        (should (= 0 (decoded-time-second decoded)))
+        (should (= 0 (decoded-time-minute decoded)))
+        (should (= 0 (decoded-time-hour decoded)))
+        ;; Check date is preserved
+        (should (= 8 (decoded-time-day decoded)))
+        (should (= 11 (decoded-time-month decoded)))
+        (should (= 2025 (decoded-time-year decoded))))
+    (test-chime--today-teardown)))
+
+;;; Boundary Cases
+
+(ert-deftest test-chime--today-boundary-midnight-returns-correct-day ()
+  "Test that chime--today at midnight returns same day."
+  (test-chime--today-setup)
+  (unwind-protect
+      (let* ((now (encode-time 0 0 0 8 11 2025))     ; Already at midnight
+             (expected (encode-time 0 0 0 8 11 2025)))
+        (cl-letf (((symbol-function 'current-time) (lambda () now)))
+          (should (equal (chime--today) expected))))
+    (test-chime--today-teardown)))
+
+(provide 'test-chime--today)
+;;; test-chime--today.el ends here