NIFI-8023 Test failure after NIFI-7996 commit if system default TZ is…

[adenes]

… CET

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[exceptionfactory]

Looking at the issue in more detail, did you evaluate AvroTypeUtil.convertToAvroObject() and how it handles the LOGICAL_TYPE_DATE? The current implementation converts from java.sql.Date.getTime() to Instant, using Instant.ofEpochMilli() and passes in the milliseconds from java.sql.Date.getTime().

Since java.sql.Date does not include the timezone, the ChronoUnit.DAYS.between() calculation returns a different number of days depending on the JVM timezone.

Changing AvroTypeUtil.convertToAvroObject() line 669 to use java.sql.Date.toLocalDate().toEpochDay() results in both tests working without any changes, and appears to operate according to the original intent of the method.

[adenes]

Thanks @exceptionfactory for the review. Actually your recommended change is the revert of the original commit that caused these test to fail (see: 83948db#diff-98d8c798133bf7b6d8a2b49a35139863b6ac85c6001787a62b3c6117abafb440L669)

I think we have a more generic issue, using java.sql.Date for representing dates is not the best solution. Being a subclass of java.util.Data means that under the hood it stores the time too, just doesn't expose it.
Storing the time leads to a "date skew" issue: when 2020-11-20 is represented as 2020-11-20 00:00 UTC but if later it's converted to a different timezone (e.g. EST, UTC-5) the same instant is presented as 2020-11-19 19:00 EST, thus the date part has changed.
This case is covered by a newly added test case: https://github.com/apache/nifi/blob/main/nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/test/java/org/apache/nifi/processors/standard/TestConvertRecord.java#L378

My opinion is that in case of dates time zone doesn't make sense (i.e. 2020-11-19 is the same date in every time zone, even if in some it starts earlier), that's why I removed the toLocalDate() call in the previously mentioned commit to fix this issue.

Unfortunately this led to these two failing tests, but I think the tests are incorrect.

[exceptionfactory]

Thanks for the background @adenes that is helpful to know. I agree with you that the underlying issue is related to using java.sql.Date for representing dates without times.

Looking at the unit test you referenced in TestConvertRecord and stepping through the code, it looks like the better place to address the problem is in DataTypeUtils.toDate() where DateFormat.parse() creates a java.util.Date. As you described, when walking through the unit test, the parse result returns a java.util.Date with a local time zone, which skews the resulting java.sql.Date. Replacing DateFormat with LocalDate.parse() and using java.sql.Date.valueOf() avoids the skewed return value. Making the change at that level would avoid the need to readjust values later on.

Making the change in DataTypeUtils.toDate() will probably have other consequences, but that seems like it is worth considering to get to the root of the problem.

[adenes]

Closing in favor of implementation in #4781