Clickhouse support for tests

[mzitnik]

Summary

Closes #6

Delete items not relevant to your PR:

• Closes Testing Junit with Embedded Flink with diffreant ClickHouse versions #6
• Unit and integration tests covering the common scenarios were added
• A human-readable description of the changes was provided to include in CHANGELOG
• For significant changes, documentation in https://github.com/ClickHouse/clickhouse-docs was updated with further explanations or tutorials

[Copilot]

Pull Request Overview

Adds support for embedded ClickHouse instances in tests, refactors Flink cluster setup, and extends CI to run tests across multiple ClickHouse versions including cloud.

• Introduce ClickHouseTestHelpers and ClickHouseServerForTests for managing test ClickHouse instances.
• Refactor EmbeddedFlinkClusterForTests for manual lifecycle control and add a combined FlinkClusterTests class.
• Update DummyFlinkClusterTest with new ClickHouse assertions and extend GitHub Actions to matrix-test against different ClickHouse versions.

Reviewed Changes

Copilot reviewed 6 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
flink-connector-clickhouse-base/src/test/java/org/apache/flink/connector/test/embedded/flink/EmbeddedFlinkClusterForTests.java	Changed package, made lifecycle methods public for manual invocation
flink-connector-clickhouse-base/src/test/java/org/apache/flink/connector/test/embedded/clickhouse/ClickHouseTestHelpers.java	Added utility methods/constants for ClickHouse versions and client setup
flink-connector-clickhouse-base/src/test/java/org/apache/flink/connector/test/embedded/clickhouse/ClickHouseServerForTests.java	New class to start/stop an embedded or cloud ClickHouse server and run SQL
flink-connector-clickhouse-base/src/test/java/org/apache/flink/connector/test/FlinkClusterTests.java	Wrapper test class to orchestrate both Flink and ClickHouse lifecycles
flink-connector-clickhouse-base/src/test/java/org/apache/flink/connector/test/DummyFlinkClusterTest.java	Updated to extend FlinkClusterTests, removed redundant imports, added ClickHouse test
.github/workflows/tests.yaml	Extended CI with version matrix, added conditional skip for missing cloud credentials

Files not reviewed (2)

• flink-connector-clickhouse-base/build.gradle.kts: Language not supported
• flink-connector-clickhouse-base/src/test/resources/log4j.properties: Language not supported

Comments suppressed due to low confidence (3)

flink-connector-clickhouse-base/src/test/java/org/apache/flink/connector/test/embedded/clickhouse/ClickHouseServerForTests.java:78

• The method name getDataBase() uses an inconsistent camel-case for 'database'. Rename it to getDatabase() for clarity and consistency.

public static String getDataBase() { return database; }

flink-connector-clickhouse-base/src/test/java/org/apache/flink/connector/test/DummyFlinkClusterTest.java:49

• The test only asserts on the collection size and no longer checks the actual mapped values. Reintroduce assertions for the expected output values to improve coverage and correctness.

Assertions.assertEquals(2, CollectSink.values.size());

.github/workflows/tests.yaml:23

• The conditional if: env.SKIP_STEP != 'true' on the checkout step will skip checking out the repository when testing cloud, causing subsequent steps to fail. You should always run checkout before conditionally skipping test execution.

- uses: actions/checkout@v3

[Copilot]

This import is no longer used after changing the base class to FlinkClusterTests. Consider removing it to clean up unused imports.

Suggested change

import org.apache.flink.connector.test.embedded.flink.EmbeddedFlinkClusterForTests;