Github user xccui commented on a diff in the pull request:
https://github.com/apache/flink/pull/6027#discussion_r188895939
--- Diff:
flink-libraries/flink-table/src/test/scala/org/apache/flink/table/expressions/ScalarOperatorsTest.scala
---
@@ -406,5 +406,26 @@ class ScalarOperatorsTest extends
ScalarOperatorsTestBase {
"((((true) === true) || false).cast(STRING) + 'X ').trim",
"trueX")
testTableApi(12.isNull, "12.isNull", "false")
+
--- End diff --
I think we can use a separate test method for `Between`. Besides, some
validation tests can be added to
`org.apache.flink.table.expressions.validation.ScalarOperatorsValidationTest`.
---
