fix IsNow

[samuelcolvin]

The following should pass

assert '2022-07-15T10:56:38.311Z' == IsNow(delta=10, tz='utc', format_string='%Y-%m-%dT%H:%M:%S.%fZ', enforce_tz=False)

(ignoring that that's not "now" any longer obvisouly)

[alexmojaki]

Here's what's happening if exceptions are allowed to propagate:

Traceback (most recent call last):
  File "/home/alex/.config/JetBrains/PyCharm2023.2/scratches/scratch_1195.py", line 3, in <module>
    assert '2023-09-15T10:56:38.311Z' == IsNow(delta=1000000, tz='utc', format_string='%Y-%m-%dT%H:%M:%S.%fZ', enforce_tz=False)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/alex/work/dirty-equals/dirty_equals/_base.py", line 104, in __eq__
    self._was_equal = self.equals(other)
                      ^^^^^^^^^^^^^^^^^^
  File "/home/alex/work/dirty-equals/dirty_equals/_numeric.py", line 118, in equals
    return self.bounds_checks(other)
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/alex/work/dirty-equals/dirty_equals/_numeric.py", line 133, in bounds_checks
    return self.approx_equals(other, delta)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/alex/work/dirty-equals/dirty_equals/_datetime.py", line 111, in approx_equals
    if not super().approx_equals(other, delta):
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/alex/work/dirty-equals/dirty_equals/_numeric.py", line 146, in approx_equals
    return abs(self.approx - other) <= delta
               ~~~~~~~~~~~~^~~~~~~
TypeError: can't subtract offset-naive and offset-aware datetimes

This fixes it:

@@ -103,8 +103,11 @@ class IsDatetime(IsNumeric[datetime]):
         else:
             raise ValueError(f'{type(other)} not valid as datetime')
 
-        if self.approx is not None and not self.enforce_tz and self.approx.tzinfo is None and dt.tzinfo is not None:
-            dt = dt.replace(tzinfo=None)
+        if self.approx is not None and not self.enforce_tz:
+            if self.approx.tzinfo is None and dt.tzinfo is not None:
+                dt = dt.replace(tzinfo=None)
+            elif self.approx.tzinfo is not None and dt.tzinfo is None:
+                dt = dt.replace(tzinfo=self.approx.tzinfo)
         return dt

but it causes failures in existing tests, e.g:

        pytest.param(
            datetime(2020, 1, 1, 12, 13, 14),
            IsDatetime(approx=datetime(2020, 1, 1, 12, 13, 14, tzinfo=timezone.utc), enforce_tz=False),
            False,
            id='tz-approx-tz',
        ),

so I'm confused about the desired behaviour.

[tekumara]

I was also expecting this to work:

        now_utc = datetime.now(timezone.utc)
        date_format = "%Y-%m-%dT%H:%M:%S.%fZ"
>       assert now_utc.strftime(date_format) == IsNow(format_string=date_format, tz=timezone.utc)
E       AssertionError: assert '2024-05-22T08:12:30.899780Z' == IsNow(approx=datetime.datetime(2024, 5, 22, 8, 35, 9, 821721, tzinfo=datetime.timezone.utc), delta=datetime.timedelta(seconds=2), format_string='%Y-%m-%dT%H:%M:%S.%fZ', tz=datetime.timezone.utc)
E        +  where '2024-05-22T08:12:30.899780Z' = <built-in method strftime of datetime.datetime object at 0x10454b4b0>('%Y-%m-%dT%H:%M:%S.%fZ')
E        +    where <built-in method strftime of datetime.datetime object at 0x10454b4b0> = datetime.datetime(2024, 5, 22, 8, 12, 30, 899780, tzinfo=datetime.timezone.utc).strftime
E        +  and   IsNow(approx=datetime.datetime(2024, 5, 22, 8, 35, 9, 821721, tzinfo=datetime.timezone.utc), delta=datetime.timedelta(seconds=2), format_string='%Y-%m-%dT%H:%M:%S.%fZ', tz=datetime.timezone.utc) = IsNow(format_string='%Y-%m-%dT%H:%M:%S.%fZ', tz=datetime.timezone.utc)
E        +    where datetime.timezone.utc = timezone.utc