Fix flaky TextIOWriteTest by loosening the shard count

[scwhittle]

Records may end up in the same shard as other records as it is random.

While modifying, simplify the test to use Iterables instead of arrays.

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[gemini-code-assist]

Summary of Changes

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This pull request addresses a flakiness issue in the TextIOWriteTest by adjusting the shard count assertion to be more tolerant of random data distribution. Concurrently, it refactors the test implementation to use Iterable instead of arrays, streamlining the test logic and enhancing code clarity.

Highlights

• Flaky Test Fix: The TextIOWriteTest was made more robust by loosening the assertion on the number of output shards. Previously, an exact shard count was expected, but due to the random nature of record distribution, records could end up in fewer shards, causing flakiness. The test now asserts that the number of shards is not empty and less than or equal to the expected maximum.
• Test Code Simplification: The test suite was refactored to consistently use Iterable<String> instead of String[] for test data. This change simplifies method signatures, removes unnecessary array conversions (e.g., Iterables.toArray), and improves the overall readability and maintainability of the test code.
• Dependency Cleanup: The unused java.util.stream.StreamSupport import was removed as part of the test simplification, further cleaning up the codebase.

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Changelog

• sdks/java/core/src/test/java/org/apache/beam/sdk/io/TextIOWriteTest.java
  • Fixed flaky shard count assertion in testWriteUnboundedWithCustomBatchParameters.
  • Refactored runTestWrite and assertOutputFiles methods to accept Iterable<String> instead of String[].
  • Removed StreamSupport import.
  • Updated all call sites to runTestWrite and assertOutputFiles to pass Iterable directly.

Activity

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[github-actions]

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R: @kennknowles for label java.

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[kennknowles]

Nice readability improvements, too.