test(core): add unit tests for normalizeHeaders and createFetchWithInit

[k61b]

Add unit tests for normalizeHeaders and createFetchWithInit in packages/core/src/shared/transport.ts.

Motivation and Context

These utility functions are used by both SSEClientTransport and StreamableHTTPClientTransport but had no dedicated unit tests. Adding coverage helps catch regressions and documents expected behavior.

How Has This Been Tested?

pnpm -C packages/core test
# 441 tests passed

Breaking Changes

None. Test-only change.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

(This is a test-only change)

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

Tests cover:

• normalizeHeaders: undefined, Headers instance, array of tuples, plain objects
• createFetchWithInit: base init passthrough, option merging, header merging precedence

[changeset-bot]

⚠️ No Changeset found

Latest commit: 59bded6

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

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commit: 59bded6

[Copilot]

Pull request overview

This PR adds comprehensive unit tests for two utility functions (normalizeHeaders and createFetchWithInit) in the transport module that previously lacked dedicated test coverage. The tests verify various input formats for header normalization and proper merging behavior for fetch initialization options.

Key changes:

• New test file with 142 lines covering two utility functions
• Tests for normalizeHeaders validate handling of undefined, Headers instances, arrays of tuples, and plain objects
• Tests for createFetchWithInit verify base initialization passthrough, option merging, and header merging precedence

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