LongFieldMapperTests test testFetchCoerced failing

[smalyshev]

LongFieldMapperTests testFetchCoerced failing

Build Scans:

• Failed CI Run

Reproduction Line:

./gradlew ":server:test" --tests "org.elasticsearch.index.mapper.LongFieldMapperTests.testFetchCoerced" -Dtests.seed=1D9DCAF60052564D -Dtests.locale=tk-Latn-TM -Dtests.timezone=Pacific/Guadalcanal -Druntime.java=24

Failure Message:

java.lang.AssertionError: fetching 3.783147882954537E18
Expected: iterable with items [<3783147882954536960L>] in any order
but: not matched: <3783147882954537000L>

Note:
This issue was created from stale AwaitsFix test. See #132306 for more details.

[elasticsearchmachine]

Pinging @elastic/es-search (Team:Search)

[elasticsearchmachine]

Pinging @elastic/es-search-foundations (Team:Search Foundations)

[smalyshev]

This problem is happening because the test is converting doubles to longs in two ways - one way is via Numbers class which uses BigDecimal and is precise, and another way is by parsing JSON that is converting it using base Double.longValue or its analogue under the hood, which loses precision. Not sure what to do about it though.

@nik9000 you wrote this test, maybe you have an idea?