[SPARK-51689] Support DataFrameWriter

[dongjoon-hyun]

What changes were proposed in this pull request?

This PR aims to support DataFrameWriter.

Why are the changes needed?

For feature parity.

Does this PR introduce any user-facing change?

No because this is a new addition to the unreleased version.

How was this patch tested?

Pass the CIs with the newly added test suite. Or, manual test.

$ swift test --filter DataFrameWriterTests
Building for debugging...
[13/13] Compiling SparkConnectTests DataFrameWriterTests.swift
Build complete! (3.63s)
Test Suite 'Selected tests' started at 2025-04-02 17:01:14.353.
Test Suite 'SparkConnectPackageTests.xctest' started at 2025-04-02 17:01:14.354.
Test Suite 'SparkConnectPackageTests.xctest' passed at 2025-04-02 17:01:14.354.
	 Executed 0 tests, with 0 failures (0 unexpected) in 0.000 (0.000) seconds
Test Suite 'Selected tests' passed at 2025-04-02 17:01:14.354.
	 Executed 0 tests, with 0 failures (0 unexpected) in 0.000 (0.002) seconds
􀟈  Test run started.
􀄵  Testing Library Version: 102 (arm64e-apple-macos13.0)
􀟈  Suite DataFrameWriterTests started.
􀟈  Test orc() started.
􀟈  Test pathAlreadyExist() started.
􀟈  Test csv() started.
􀟈  Test overwrite() started.
􀟈  Test sortByBucketBy() started.
􀟈  Test json() started.
􀟈  Test save() started.
􀟈  Test partitionBy() started.
􀟈  Test parquet() started.
􁁛  Test sortByBucketBy() passed after 0.072 seconds.
􁁛  Test pathAlreadyExist() passed after 0.396 seconds.
􁁛  Test overwrite() passed after 0.504 seconds.
􁁛  Test orc() passed after 0.515 seconds.
􁁛  Test json() passed after 0.524 seconds.
􁁛  Test parquet() passed after 0.539 seconds.
􁁛  Test partitionBy() passed after 0.549 seconds.
􁁛  Test csv() passed after 0.569 seconds.
􁁛  Test save() passed after 1.001 seconds.
􁁛  Suite DataFrameWriterTests passed after 1.002 seconds.
􁁛  Test run with 9 tests passed after 1.002 seconds.

Was this patch authored or co-authored using generative AI tooling?

No.

[peter-toth]

Nit: technically, Spark produces 3 different errors

• when only sortBy and
• when only bucketedBy and
• when both

are specified, so adding a bucketedBy only test case might make sense.

[dongjoon-hyun]

Thank you, @peter-toth .

[dongjoon-hyun]

Merged to main.