Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/5016#discussion_r151099552
--- Diff:
flink-libraries/flink-table/src/test/scala/org/apache/flink/table/runtime/stream/table/TableSourceITCase.scala
---
@@ -154,6 +154,40 @@ class TableSourceITCase extends
StreamingMultipleProgramsTestBase {
}
@Test
+ def testRowtimeTableSourceWithoutWMStrategy(): Unit = {
--- End diff --
The test does not really check that watermarks are preserved.
We would need a `TableSource` with a non-parallel `SourceFunction` that
emits records and watermarks, similar to
`TimeTestUtil.EventTimeSourceFunction`.
There are two ways to ensure that the watermarks have been preserved:
1. easy / not precise: we emit late data from the TableSource and validated
that the late data is not included in the result
2. more complex / precise: We run a simple select project query on the
table and convert the query result into an append `DataStream`. Finally, we
need to check that all watermarks have been preserved using a custom operator
(other functions do not have access to watermarks).
---
