diff --git a/functions.org b/functions.org
index 84b99d1..5653735 100644
--- a/functions.org
+++ b/functions.org
@@ -1,4 +1,4 @@
-* TODO Test coverage [5/44]
+* TODO Test coverage [6/44]
   - [ ] timeclock-list-idle-timer ()
   - [ ] timeclock-list-current-project ()
   - [ ] timeclock-list-project-active? (project)
@@ -7,7 +7,7 @@
   - [ ] timeclock-list-project-at-point ()
   - [ ] timeclock-list-goto-last-project ()
   - [X] timeclock-list-time-add (a b)
-  - [ ] timeclock-list-total-time-one-day (&optional date)
+  - [X] timeclock-list-total-time-one-day (&optional date)
   - [ ] timeclock-list-print-non-tabular ()
   - [ ] timeclock-list-toggle-project (&optional arg)
   - [ ] timeclock-list (&optional arg)
diff --git a/timeclock-ui-tests.el b/timeclock-ui-tests.el
index 56b92ce..acef7f7 100644
--- a/timeclock-ui-tests.el
+++ b/timeclock-ui-tests.el
@@ -246,6 +246,7 @@
                  [1 1 1])))
 
 (ert-deftest timeclock-list-time-add-tests ()
+  "Tests for `timeclock-list-time-add'."
   (should (equal (timeclock-list-time-add [0 0 0] [0 0 0])
                  [0 0 0]))
   (should (equal (timeclock-list-time-add [0 0 1] [0 0 0])
@@ -257,6 +258,20 @@
   (should (equal (timeclock-list-time-add [0 1 1] [0 59 59])
                  [1 1 0])))
 
+(ert-deftest timeclock-list-ttod-tests ()
+  "Tests for `timeclock-list-total-time-one-day'."
+  (let ((timeclock-file "test.timelog"))
+    (timeclock-reread-log)
+    (should (equal (timeclock-list-total-time-one-day '(0 0 0 1 1 2018))
+                   [5 0 0]))
+    (should (equal (timeclock-list-total-time-one-day '(0 0 0 2 1 2018))
+                   [1 0 0]))
+    (should (equal (timeclock-list-total-time-one-day '(0 0 0 3 1 2018))
+                   [1 0 0]))))
+
+;; (ert-deftest timeclock-report-iodd-tests ()
+;;   (should (equal (timeclock-report-increment-or-decrement-date '(0 0 0 28 2 2020) '+))))
+
 (provide 'timeclock-ui-tests)
 
 ;; Local Variables: