Merge pull request #1192 from NHSDigital/DTOSS-12370-improve-relative-date-formatting

Improve relative date formatting

Author: MatMoore

manage_breast_screening/core/utils/date_formatting.py

@@ -20,7 +20,7 @@ def format_date(value):
     return value.strftime("%-d %B %Y")
 
 
-def format_relative_date(value: datetime | date):
+def format_relative_date(value: datetime | date, round_days=True):
     """
     Format a date relative to today as a number of days.
     """
@@ -30,7 +30,7 @@ def format_relative_date(value: datetime | date):
     today = date.today()
     days = (value - today).days
 
-    amount = _format_date_difference(value, today)
+    amount = _format_date_difference(value, today, round_days=round_days)
 
     if days < -1:
         return f"{amount} ago"
@@ -80,9 +80,25 @@ def format_year_with_relative(value: int | None):
         return str(value)
 
 
-def _format_date_difference(date1, date2):
+def _format_date_difference(date1, date2, round_days=True):
     diff = relativedelta(date1, date2) if date1 > date2 else relativedelta(date2, date1)
 
+    if round_days and diff.days and (diff.months or diff.years):
+        # If the delta is at least 1 month, and we don't want the exact days,
+        # then pretend that date1 is more recent than the true value so that
+        # the month aligns with date2.
+        #
+        # If the delta is positive (date1 is in the future of date2) then
+        # the formatted delta will be bigger than the true delta.
+        #
+        # If the delta is negative (date1 is in the past of date2) then
+        # the formatted delta will be smaller than the true delta.
+        diff.days = 0
+        if date1 > date2:
+            months = diff.months
+            diff.months = (months + 1) % 12
+            diff.years += (months + 1) // 12
+
     parts = []
     if diff.years:
         parts.append("1 year" if diff.years == 1 else f"{diff.years} years")

manage_breast_screening/core/utils/tests/test_date_formatting.py

@@ -15,22 +15,32 @@
 
 @time_machine.travel(datetime(2025, 5, 2, 10, tzinfo=ZoneInfo("Europe/London")))
 @pytest.mark.parametrize(
-    ("dateiso", "output"),
+    ("dateiso", "round_days", "output"),
     (
-        ("2025-05-02T09:00:00", "today"),
-        ("2025-05-01T09:00:00", "yesterday"),
-        ("2025-05-01T11:59:00", "yesterday"),
-        ("2025-04-30T08:00:00", "2 days ago"),
-        ("2025-05-03T07:00:00", "tomorrow"),
-        ("2025-05-04T12:00:00", "in 2 days"),
-        ("2024-05-02T12:00:00", "1 year ago"),
-        ("2024-04-02T12:00:00", "1 year, 1 month ago"),
-        ("2024-03-31T12:00:00", "1 year, 1 month, 2 days ago"),
-        ("2026-03-31T12:00:00", "in 10 months, 29 days"),
+        ("2025-05-02T09:00:00", True, "today"),
+        ("2025-05-02T09:00:00", False, "today"),
+        ("2025-05-01T09:00:00", True, "yesterday"),
+        ("2025-05-01T11:59:00", True, "yesterday"),
+        ("2025-04-30T08:00:00", True, "2 days ago"),
+        ("2025-04-30T08:00:00", False, "2 days ago"),
+        ("2025-05-03T07:00:00", True, "tomorrow"),
+        ("2025-05-04T12:00:00", True, "in 2 days"),
+        ("2024-05-02T12:00:00", True, "1 year ago"),
+        ("2024-04-02T12:00:00", True, "1 year, 1 month ago"),
+        ("2024-03-31T12:00:00", False, "1 year, 1 month, 2 days ago"),
+        ("2024-03-31T12:00:00", True, "1 year, 1 month ago"),
+        ("2026-03-31T12:00:00", True, "in 11 months"),
+        ("2026-03-31T12:00:00", False, "in 10 months, 29 days"),
+        ("2026-04-30T12:00:00", True, "in 1 year"),
+        ("2026-04-30T12:00:00", False, "in 11 months, 28 days"),
+        ("2027-04-30T12:00:00", True, "in 2 years"),
     ),
 )
-def test_relative_dates(dateiso, output):
-    assert format_relative_date(datetime.fromisoformat(dateiso)) == output
+def test_relative_dates(dateiso, round_days, output):
+    assert (
+        format_relative_date(datetime.fromisoformat(dateiso), round_days=round_days)
+        == output
+    )
 
 
 @time_machine.travel(datetime(2025, 5, 2, 10, tzinfo=ZoneInfo("Europe/London")))

manage_breast_screening/mammograms/tests/presenters/test_appointment_presenters.py

@@ -757,7 +757,7 @@ def test_slot_timestamp_multi_line(self, clinic_slot_mock):
 
         assert (
             ClinicSlotPresenter(clinic_slot_mock).slot_timestamp_multi_line
-            == "9:30am (30 minutes) - 2 January 2025 (4 months, 17 days ago)"
+            == "9:30am (30 minutes) - 2 January 2025 (4 months ago)"
         )
 
     @time_machine.travel(datetime(2025, 5, 19, tzinfo=tz.utc))