diff --git a/test/Tests/src/Data/Time/Date_Time_Spec.enso b/test/Tests/src/Data/Time/Date_Time_Spec.enso
index ba65ad70b9168..65410aabe6540 100644
--- a/test/Tests/src/Data/Time/Date_Time_Spec.enso
+++ b/test/Tests/src/Data/Time/Date_Time_Spec.enso
@@ -331,11 +331,15 @@ spec_with name create_new_datetime parse_datetime nanoseconds_loss_in_precision=
             d1.start_of (Date_Period.Week first_day=Day_Of_Week.Saturday) . should_equal (Date_Time.new 2022 9 10)
             d1.end_of (Date_Period.Week first_day=Day_Of_Week.Saturday) . should_equal (Date_Time.new 2022 9 16 23 59 59 max_nanos)
 
-            d2 = create_new_datetime 2022 2 7 12 34 56 123456789
+            d2 = create_new_datetime 2022 2 6 12 34 56 123456789
             d2.start_of Date_Period.Quarter . should_equal (Date_Time.new 2022 1 1)
             d2.end_of Date_Period.Quarter . should_equal (Date_Time.new 2022 3 31 23 59 59 max_nanos)
             d2.start_of Date_Period.Month . should_equal (Date_Time.new 2022 2 1)
             d2.end_of Date_Period.Month . should_equal (Date_Time.new 2022 2 28 23 59 59 max_nanos)
+            d2.start_of (Date_Period.Week) . should_equal (Date_Time.new 2022 1 31)
+            d2.end_of (Date_Period.Week) . should_equal (Date_Time.new 2022 2 6 23 59 59 max_nanos)
+            d2.start_of (Date_Period.Week first_day=Day_Of_Week.Sunday) . should_equal (Date_Time.new 2022 2 6)
+            d2.end_of (Date_Period.Week first_day=Day_Of_Week.Sunday) . should_equal (Date_Time.new 2022 2 12 23 59 59 max_nanos)
 
             d3 = create_new_datetime 2020 2 19
             d3.start_of Date_Period.Year . should_equal (Date_Time.new 2020 1 1)