[FLINK-25228][table] Introduce flink-table-test-utils

[slinkydeveloper]

What is the purpose of the change

Goal of this new module is to provide a easy to use module for testing formats, connectors and end users.

The module brings in transitively all the dependencies you need to run a table test and includes a couple of test utilities.

Brief change log

• Introduce flink-table-test-utils, shipping the existing table assertions and TableFactoryHarness. Both assertions and TableFactoryHarness are marked as @Experimental
• Expand the existing table assertions
• Show the usage of the assertions

Verifying this change

The newly introduced assertions are tested in a new test, showing how to use them.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): yes
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? yes
• If yes, how is the feature documented? JavaDocs

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Last check on commit 0fad0a9 (Mon Jan 03 08:22:36 UTC 2022)

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CI report:

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[twalthr]

Thanks for the PR @slinkydeveloper. I totally support this PR but I would like to remove confusion in the code base and duplicate code. Let's move classes from table-common and other locations to the new test utils package. If it is only about DataStructureConverter we can also perform a class lookup whether flink-table-runtime is present or not. That should be fine for test utils.

[twalthr]

This already comes in through flink-test-utils-junit.

[slinkydeveloper]

flink-test-utils pulls flink-test-utils-junit, but we need to redeclare it here as the parent pom somewhere declares it with scope test, so we need to override the scope here. Removing flink-test-utils-junit returns this:

[INFO] org.apache.flink:flink-table-test-utils:jar:1.15-SNAPSHOT
[INFO] +- org.apache.flink:flink-test-utils:jar:1.15-SNAPSHOT:compile
[INFO] |  +- org.apache.flink:flink-test-utils-junit:jar:1.15-SNAPSHOT:test

[twalthr]

Maybe document the intention as well: In the future we plan to expose this module to users. It should not contain internal/very specialized testing utilities.

[slinkydeveloper]

I doubled down, check now :)

[slinkydeveloper]

@twalthr the reason for placing the classes in two places is to continue to use the asserts in table-common test classpath as well.

If it is only about DataStructureConverter we can also perform a class lookup whether flink-table-runtime is present or not

That's something I can do with some reflections. This way, we can still use the assertions within table-common (without some methods that requires the runtime dep), and then we don't have duplicated code. But we'll still need the shading. Is it ok for you?

[slinkydeveloper]

@twalthr ready for another pass

[twalthr]

Thanks for the update @slinkydeveloper. We still need to remove the duplicate TableFactoryHarness.

[slinkydeveloper]

@twalthr as discussed, I've removed the table factory harness

[twalthr]

LGTM