Switch get_previous_interval precision to milliseconds to match Edge

geomagio/Controller.py

@@ -653,11 +653,11 @@ def get_previous_interval(
     Returns
     -------
     Previous interval of approximately the same size.
-    Interval is rounded to nearest second, and ends one microsecond earlier.
+    Interval is rounded to nearest second, and ends one millisecond earlier.
     """
     # round to nearest second to recover removed microsecond from repeated calls
     interval_size = round(end - start)
-    return (start - interval_size, start - 1e-6)
+    return (start - interval_size, start - 1e-3)
 
 
 def get_realtime_interval(interval_seconds: int) -> Tuple[UTCDateTime, UTCDateTime]:

test/Controller_test.py

@@ -301,12 +301,12 @@ def test_get_previous_interval():
     previous = get_previous_interval(start=start, end=end)
     assert previous == (
         UTCDateTime("2022-01-04T23:00:00"),
-        UTCDateTime("2022-01-04T23:59:59.999999Z"),
+        UTCDateTime("2022-01-04T23:59:59.999Z"),
     )
     # previous interval still starts at beginning of previous hour
-    # even though interval is one microsecond smaller
+    # even though interval is one millisecond smaller
     previous = get_previous_interval(*previous)
     assert previous == (
         UTCDateTime("2022-01-04T22:00:00"),
-        UTCDateTime("2022-01-04T22:59:59.999999Z"),
+        UTCDateTime("2022-01-04T22:59:59.999Z"),
     )