Use datetime.isoformat to ensure timezone handling is correct (#987)

* Use datetime.isoformat to ensure timezone handling is correct

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update changelog

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

CHANGELOG.md

@@ -8,6 +8,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/).
 ### Fixed
 - Further handling for readonly files
 - Improved chopping with axes that span the kept axes removed
+- Timezone offset for `wt.kit.TimeStamp.RFC3339`
 
 ## [3.3.2]
 

WrightTools/kit/_timestamp.py

@@ -118,6 +118,9 @@ def __str__(self):
         """Readable representation."""
         return self.RFC3339
 
+    def __eq__(self, other):
+        return self.datetime == other.datetime
+
     @property
     def date(self):
         """year-month-day."""
@@ -151,27 +154,7 @@ def RFC3339(self):
 
         __ https://www.ietf.org/rfc/rfc3339.txt
         """
-        # get timezone offset
-        delta_sec = time.timezone
-        m, s = divmod(delta_sec, 60)
-        h, m = divmod(m, 60)
-        # timestamp
-        format_string = "%Y-%m-%dT%H:%M:%S.%f"
-        out = self.datetime.strftime(format_string)
-        # timezone
-        if delta_sec == 0.0:
-            out += "Z"
-        else:
-            if delta_sec > 0:
-                sign = "+"
-            elif delta_sec < 0:
-                sign = "-"
-
-            def as_string(num):
-                return str(np.abs(int(num))).zfill(2)
-
-            out += sign + as_string(h) + ":" + as_string(m)
-        return out
+        return self.datetime.isoformat()
 
     @property
     def RFC5322(self):

tests/kit/timestamp.py

@@ -36,6 +36,7 @@ def test_human():
 def test_RFC3339():
     ts = wt.kit.TimeStamp()
     assert ts.RFC3339
+    assert wt.kit.timestamp_from_RFC3339(ts.RFC3339) == ts
 
 
 def test_RFC5322():