KTOR-9168 Add regression test for case-insensitive Set-Cookie merging in CIO

[fru1tworld]

Subsystem

Client / CIO

Motivation

KTOR-9168 (CIO dropping case-different Set-Cookie headers) was inadvertently fixed by #5379. Add a wire-level regression test to guard the case-insensitive dedup behavior.

Solution

Test only — no production code changes.

Closes KTOR-9168

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: a4d36725-ab1f-42ef-96e4-41f51d47521f

📥 Commits

Reviewing files that changed from the base of the PR and between a1651e3 and acd6ff1.

📒 Files selected for processing (1)

• ktor-client/ktor-client-cio/jvm/test/io/ktor/client/engine/cio/CookieHeaderCaseTest.kt

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📝 Walkthrough

Walkthrough

A new test file is added to verify that the CIO HTTP client engine correctly preserves Set-Cookie response headers regardless of casing in the header name (e.g., "Set-Cookie" vs "set-cookie").

Changes

Set-Cookie Header Case Handling Test

Layer / File(s)	Summary
Test Implementation ktor-client/ktor-client-cio/jvm/test/io/ktor/client/engine/cio/CookieHeaderCaseTest.kt	New test class that spins up a mock HTTP server using ServerSocket, responds with two Set-Cookie headers using different casing, and asserts the CIO client correctly collects both cookies via response.headers.getAll(HttpHeaders.SetCookie).

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Suggested reviewers

• osipxd

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and specifically summarizes the main change: adding a regression test for case-insensitive Set-Cookie header handling in CIO.
Description check	✅ Passed	The description includes all required template sections (Subsystem, Motivation, Solution) with clear explanations of the bug, the fix, and the test addition.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[bjhham]

Thanks, looks good 👍