kv: add comprehensive tests for Batch operations

[vishalv1994]

This commit adds extensive unit tests for the kv.Batch type, covering all major operations including Get, Put, Scan, Delete, conditional operations, bulk operations, and admin methods. Tests also cover error handling, buffer management, and raw vs non-raw batch mixing.

Release notes: None

Epic: None

[blathers-crl]

Your pull request contains more than 1000 changes. It is strongly encouraged to split big PRs into smaller chunks.

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[cockroach-teamcity]

This change is 

[Copilot]

Pull Request Overview

This PR adds comprehensive unit tests for the kv.Batch type to improve test coverage of batch operations. The tests cover all major batch functionality including basic operations (Get, Put, Scan, Delete), conditional operations, bulk operations, error handling, and batch validation.

Key changes:

• Adds 492 lines of comprehensive unit tests for the Batch type
• Tests cover Get, Put, CPut, Inc, Scan, Delete, and bulk operations
• Includes tests for error handling, buffer management, and raw vs non-raw batch mixing
• Updates BUILD.bazel to include the new test file

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
pkg/kv/batch_test.go	New comprehensive test file covering all Batch operations, error handling, and edge cases
pkg/kv/BUILD.bazel	Adds batch_test.go to the test sources list

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[Copilot]

The Next() method doesn't check bounds and will panic if called beyond the data length. Add bounds checking: if m.index >= len(m.data) { return nil, nil } or similar error handling.

Suggested change

	m.index++
	m.index++
	if m.index >= len(m.data) {
	return nil, nil
	}

[Copilot]

The Next() method doesn't check bounds and will panic if called beyond the data length. Add bounds checking: if m.index >= len(m.data) { return nil, roachpb.Value{} } or similar error handling.

Suggested change

	m.index++
	m.index++
	if m.index >= len(m.data) {
	return nil, roachpb.Value{}
	}