Encapsulate date_range... fn in FiniteDatetimeRange

This moves/renames `ranges.date_range_for_midnight_range` so it's a method: `FiniteDatetimeRange.as_date_range` - more concise. Before: ranges.date_range_for_midnight_range( dt_range.localize(my_timezone) # common pre-step ) After: dt_range.localize(my_timezone).as_date_range() The behaviour is unchanged: only midnight ranges, which fully span a date range, are supported in the conversion.
octoenergy · Dec 18, 2024 · 2786ddb · 2786ddb
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -2,6 +2,9 @@
 
 ## Unreleased
 
+- Add `FiniteDatetimeRange.as_date_range` [#181](https://github.com/octoenergy/xocto/pull/181)
+- [Breaking] Remove `ranges.date_range_for_midnight_range` (replaced by FiniteDatetimeRange.as_date_range)[#181] (https://github.com/octoenergy/xocto/pull/181)
+
 ## v6.2.0 - 2024-12-11
 
 - Add `ranges.date_range_for_midnight_range` [#178] (https://github.com/octoenergy/xocto/pull/178)

diff --git a/tests/test_ranges.py b/tests/test_ranges.py
@@ -1028,6 +1028,53 @@ def test_errors_if_naive(self):
 
             assert "naive" in str(exc_info.value)
 
+    class TestAsDateRange:
+        def test_returns_date_range(self):
+            dt_range = ranges.FiniteDatetimeRange(
+                datetime.datetime(2020, 1, 1),
+                datetime.datetime(2020, 1, 10),
+            )
+
+            assert dt_range.as_date_range() == ranges.FiniteDateRange(
+                datetime.date(2020, 1, 1),
+                datetime.date(2020, 1, 9),
+            )
+
+        def test_errors_if_different_timezones(self):
+            dt_range = ranges.FiniteDatetimeRange(
+                datetime.datetime(2020, 1, 1, tzinfo=zoneinfo.ZoneInfo("Asia/Dubai")),
+                datetime.datetime(
+                    2020, 1, 10, tzinfo=zoneinfo.ZoneInfo("Australia/Sydney")
+                ),
+            )
+
+            with pytest.raises(ValueError) as exc_info:
+                dt_range.as_date_range()
+
+            assert "Start and end in different timezones" in str(exc_info.value)
+
+        def test_errors_if_start_not_midnight(self):
+            dt_range = ranges.FiniteDatetimeRange(
+                datetime.datetime(2020, 1, 1, hour=1),
+                datetime.datetime(2020, 1, 10),
+            )
+
+            with pytest.raises(ValueError) as exc_info:
+                dt_range.as_date_range()
+
+            assert "Start of range is not midnight-aligned" in str(exc_info.value)
+
+        def test_errors_if_end_not_midnight(self):
+            dt_range = ranges.FiniteDatetimeRange(
+                datetime.datetime(2020, 1, 1),
+                datetime.datetime(2020, 1, 10, hour=1),
+            )
+
+            with pytest.raises(ValueError) as exc_info:
+                dt_range.as_date_range()
+
+            assert "End of range is not midnight-aligned" in str(exc_info.value)
+
 
 class TestAsFiniteDatetimePeriods:
     def test_converts(self):
@@ -1187,54 +1234,6 @@ def test_yields_correct_ranges(self, row):
         assert result == row["expected"]
 
 
-class TestDateRangeForMidnightRange:
-    def test_returns_date_range(self):
-        dt_range = ranges.FiniteDatetimeRange(
-            datetime.datetime(2020, 1, 1),
-            datetime.datetime(2020, 1, 10),
-        )
-
-        assert ranges.date_range_for_midnight_range(dt_range) == ranges.FiniteDateRange(
-            datetime.date(2020, 1, 1),
-            datetime.date(2020, 1, 9),
-        )
-
-    def test_errors_if_different_timezones(self):
-        dt_range = ranges.FiniteDatetimeRange(
-            datetime.datetime(2020, 1, 1, tzinfo=zoneinfo.ZoneInfo("Asia/Dubai")),
-            datetime.datetime(
-                2020, 1, 10, tzinfo=zoneinfo.ZoneInfo("Australia/Sydney")
-            ),
-        )
-
-        with pytest.raises(ValueError) as exc_info:
-            ranges.date_range_for_midnight_range(dt_range)
-
-        assert "Start and end in different timezones" in str(exc_info.value)
-
-    def test_errors_if_start_not_midnight(self):
-        dt_range = ranges.FiniteDatetimeRange(
-            datetime.datetime(2020, 1, 1, hour=1),
-            datetime.datetime(2020, 1, 10),
-        )
-
-        with pytest.raises(ValueError) as exc_info:
-            ranges.date_range_for_midnight_range(dt_range)
-
-        assert "Start of range is not midnight-aligned" in str(exc_info.value)
-
-    def test_errors_if_end_not_midnight(self):
-        dt_range = ranges.FiniteDatetimeRange(
-            datetime.datetime(2020, 1, 1),
-            datetime.datetime(2020, 1, 10, hour=1),
-        )
-
-        with pytest.raises(ValueError) as exc_info:
-            ranges.date_range_for_midnight_range(dt_range)
-
-        assert "End of range is not midnight-aligned" in str(exc_info.value)
-
-
 def _rangeset_from_string(rangeset_str: str) -> ranges.RangeSet[int]:
     """
     Convenience method to make test declarations clearer.

diff --git a/xocto/ranges.py b/xocto/ranges.py
@@ -904,6 +904,36 @@ def localize(self, tz: datetime.tzinfo) -> FiniteDatetimeRange:
             self.end.astimezone(tz),
         )
 
+    def as_date_range(
+        self: FiniteDatetimeRange,
+    ) -> FiniteDateRange:
+        """
+        Returns the date range covered by this range (if midnight-aligned).
+
+        This can be useful where a range is available at datetime granularity,
+        but is used in functions that operate at date granularity.
+
+        Raises:
+            ValueError:
+                If the range boundaries are in different timezeones.
+                If the range boundaries are not midnight-aligned.
+        """
+        # First check range timezone is uniform.
+        if self.start.tzinfo != self.end.tzinfo:
+            raise ValueError("Start and end in different timezones")
+
+        # Check datetimes are both midnight-aligned.
+        if self.start.time() != datetime.time(0, 0):
+            raise ValueError("Start of range is not midnight-aligned")
+
+        if self.end.time() != datetime.time(0, 0):
+            raise ValueError("End of range is not midnight-aligned")
+
+        return FiniteDateRange(
+            self.start.date(),
+            self.end.date() - datetime.timedelta(days=1),
+        )
+
 
 class FiniteDateRange(FiniteRange[datetime.date]):
     """
@@ -1085,34 +1115,3 @@ def iterate_over_months(
 
         yield FiniteDatetimeRange(start_at, this_end)
         start_at = next_start
-
-
-def date_range_for_midnight_range(
-    range: FiniteDatetimeRange,
-) -> FiniteDateRange:
-    """
-    Returns the date range of a midnight-aligned datetime range.
-
-    This can be useful where a range is available at datetime granularity,
-    but is used in functions that operate at date granularity.
-
-    Raises:
-        ValueError:
-            If the range boundaries are in different timezeones.
-            If the range boundaries are not midnight-aligned.
-    """
-    # First check range timezone is uniform.
-    if range.start.tzinfo != range.end.tzinfo:
-        raise ValueError("Start and end in different timezones")
-
-    # Check datetimes are both midnight-aligned.
-    if range.start.time() != datetime.time(0, 0):
-        raise ValueError("Start of range is not midnight-aligned")
-
-    if range.end.time() != datetime.time(0, 0):
-        raise ValueError("End of range is not midnight-aligned")
-
-    return FiniteDateRange(
-        range.start.date(),
-        range.end.date() - datetime.timedelta(days=1),
-    )