[GH] (texera/gh-readonly-queue/main/pr-5952-363308bfa7a880f4e33fbfc42b35e51d2e044c6a): Workflow run "Required Checks" is working again!

[GitBox <gi...@apache.org>]

The GitHub Actions job "Required Checks" on texera.git/gh-readonly-queue/main/pr-5952-363308bfa7a880f4e33fbfc42b35e51d2e044c6a has succeeded.
Run started by GitHub user aglinxinyuan (triggered by aglinxinyuan).

Head commit for run:
2ec7c076cb41c840bd052d8b86f4ac93c05d974c / Xinyuan Lin <xi...@uci.edu>
test(workflow-operator): add unit test coverage for Sklearn prediction/testing/linear-regression descriptors (#5952)

### What changes were proposed in this PR?

Pin behavior of three previously-untested Sklearn model-lifecycle
descriptors in `common/workflow-operator`. No production-code changes.
Unlike the classifier family, these extend `PythonOperatorDescriptor`
directly, so each has its own contract.

| Spec | Source class | Tests |
| --- | --- | --- |
| `SklearnLinearRegressionOpDescSpec` | `SklearnLinearRegressionOpDesc`
| 5 |
| `SklearnPredictionOpDescSpec` | `SklearnPredictionOpDesc` | 5 |
| `SklearnTestingOpDescSpec` | `SklearnTestingOpDesc` | 6 |

**Behavior pinned**

| Surface | Contract |
| --- | --- |
| `operatorInfo` | exact name/description; Sklearn group; correct
multi-port shapes (LinearRegression training/testing + blocking output;
Prediction model/data; Testing model/data) |
| field defaults | LinearRegression `target` null / `degree` 1;
Prediction `model`/`resultAttribute` null, `groundTruthAttribute` `""`;
Testing `isRegression` false, `model`/`target` null |
| `getOutputSchemas` | LinearRegression → `model_name`/`model`;
Prediction → input (port 1) + result attribute; Testing → input (port 0)
+ classification (`accuracy`/`f1`/`precision`/`recall`) or regression
(`R2`/`RMSE`/`MAE`) metric columns |
| `generatePythonCode` | emits the expected estimator import / pipeline
/ scorer fragments |
| Round-trip | config fields preserved through the polymorphic
`LogicalOp` base, with the correct `operatorType` discriminator |

### Any related issues, documentation, discussions?

Part of the ongoing `workflow-operator` unit-test coverage effort.

### How was this PR tested?

- `sbt "WorkflowOperator/testOnly *SklearnLinearRegressionOpDescSpec
*SklearnPredictionOpDescSpec *SklearnTestingOpDescSpec"` — 16 tests, all
green
- `sbt "WorkflowOperator/Test/scalafmtCheck"` and `sbt
"WorkflowOperator/scalafixAll --check"` — clean
- CI to confirm

### Was this PR authored or co-authored using generative AI tooling?

Generated-by: Claude Code (Opus 4.8 [1M context])

Report URL: https://github.com/apache/texera/actions/runs/28270423371

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