[Fix][E2E] Fix flaky CI failure in KingbaseDialectContainerTest

[dybyte]

Purpose of this pull request

KingbaseDialectContainerTest were occasionally failing with NullPointerException in CI.

The previous test structure relied on shared static state and reused JDBC connections across test execution, which made the tests sensitive to lifecycle ordering and shared resource state.

Does this PR introduce any user-facing change?

How was this patch tested?

Check list

• If any new Jar binary package adding in your PR, please add License Notice according
  New License Guide
• If necessary, please update the documentation to describe the new feature. https://github.com/apache/seatunnel/tree/dev/docs
• If necessary, please update incompatible-changes.md to describe the incompatibility caused by this PR.
• If you are contributing the connector code, please check that the following files are updated:
  1. Update plugin-mapping.properties and add new connector information in it
  2. Update the pom file of seatunnel-dist
  3. Add ci label in label-scope-conf
  4. Add e2e testcase in seatunnel-e2e
  5. Update connector plugin_config

[LeonYoah]

I still see the same intermittent NPE in CI. My guess is that the CI runner is more timing-sensitive, so although the Kingbase container port is already open, the database itself is not yet fully ready to execute SQL. In that case, the test starts its initialization too early and occasionally fails. We may need an extra readiness check after container startup, and only expose the connection / continue with downstream test setup once the database can actually execute SQL successfully.

[dybyte]

I still see the same intermittent NPE in CI. My guess is that the CI runner is more timing-sensitive, so although the Kingbase container port is already open, the database itself is not yet fully ready to execute SQL. In that case, the test starts its initialization too early and occasionally fails. We may need an extra readiness check after container startup, and only expose the connection / continue with downstream test setup once the database can actually execute SQL successfully.

Thanks, this was very helpful!
I’ve added a SQL readiness check to address this.

[LeonYoah]

@chl-wxp

[LeonYoah]

LGTM

[davidzollo]

+1
Good job

[Carl-Zhou-CN]

+1