Fix TzInfo equality check based on offset (#1197)

Co-authored-by: David Hewitt <[email protected]>

Author: 13sin

src/input/datetime.rs

@@ -563,8 +563,19 @@ impl TzInfo {
         hasher.finish()
     }
 
-    fn __richcmp__(&self, other: &Self, op: CompareOp) -> bool {
-        op.matches(self.seconds.cmp(&other.seconds))
+    fn __richcmp__(&self, other: &PyAny, op: CompareOp) -> PyResult<Py<PyAny>> {
+        let py = other.py();
+        if other.is_instance_of::<PyTzInfo>() {
+            let offset_delta = other.call_method1(intern!(py, "utcoffset"), (py.None(),))?;
+            if offset_delta.is_none() {
+                return Ok(py.NotImplemented());
+            }
+            let offset_seconds: f64 = offset_delta.call_method0(intern!(py, "total_seconds"))?.extract()?;
+            let offset = offset_seconds.round() as i32;
+            Ok(op.matches(self.seconds.cmp(&offset)).into_py(py))
+        } else {
+            Ok(py.NotImplemented())
+        }
     }
 
     fn __deepcopy__(&self, py: Python, _memo: &PyDict) -> PyResult<Py<Self>> {

tests/test_tzinfo.py

@@ -1,11 +1,15 @@
 import copy
 import functools
 import pickle
+import sys
 import unittest
 from datetime import datetime, timedelta, timezone, tzinfo
 
 from pydantic_core import SchemaValidator, TzInfo, core_schema
 
+if sys.version_info >= (3, 9):
+    from zoneinfo import ZoneInfo
+
 
 class _ALWAYS_EQ:
     """
@@ -80,6 +84,7 @@ class TestTzInfo(unittest.TestCase):
     def setUp(self):
         self.ACDT = TzInfo(timedelta(hours=9.5).total_seconds())
         self.EST = TzInfo(-timedelta(hours=5).total_seconds())
+        self.UTC = TzInfo(timedelta(0).total_seconds())
         self.DT = datetime(2010, 1, 1)
 
     def test_str(self):
@@ -163,6 +168,17 @@ def test_comparison(self):
         self.assertFalse(tz <= SMALLEST)
         self.assertTrue(tz >= SMALLEST)
 
+        # offset based comparion tests for tzinfo derived classes like datetime.timezone.
+        utcdatetime = self.DT.replace(tzinfo=timezone.utc)
+        self.assertTrue(tz == utcdatetime.tzinfo)
+        estdatetime = self.DT.replace(tzinfo=timezone(-timedelta(hours=5)))
+        self.assertTrue(self.EST == estdatetime.tzinfo)
+        self.assertTrue(tz > estdatetime.tzinfo)
+        if sys.version_info >= (3, 9) and sys.platform == 'linux':
+            self.assertFalse(tz == ZoneInfo('Europe/London'))
+            with self.assertRaises(TypeError):
+                tz > ZoneInfo('Europe/London')
+
     def test_copy(self):
         for tz in self.ACDT, self.EST:
             tz_copy = copy.copy(tz)