Fix deterministic E2E proxy SSE endpoint rewrite tests#4093
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aponcedeleonch merged 1 commit intomainfrom Mar 11, 2026
Merged
Fix deterministic E2E proxy SSE endpoint rewrite tests#4093aponcedeleonch merged 1 commit intomainfrom
aponcedeleonch merged 1 commit intomainfrom
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These SSE endpoint rewrite tests were orphaned from CI until the matrix rebalance (#4074), then had stale flags fixed (#4080), but have never actually passed. Four root causes are addressed: 1. GenerateMCPServerURL omits /sse for remote SSE URLs with empty path, causing waitForInitializeSuccess to GET / instead of /sse (404). 2. getSSERewriteConfig reads X-Forwarded-* from the outbound request which has auto-injected headers from SetXForwarded(), converting relative endpoint URLs into absolute ones with the proxy's own host. 3. Test 3 mock server lacks a 404 fallback for non-/sse paths. 4. Test 4 (OSV + endpoint-prefix) fails due to #3372; skip it. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #4093 +/- ##
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- Coverage 68.52% 68.52% -0.01%
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Files 447 447
Lines 45679 45691 +12
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+ Hits 31300 31308 +8
- Misses 11963 11966 +3
- Partials 2416 2417 +1 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
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jhrozek
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Mar 11, 2026
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jhrozek
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there are still some flaky tests but the one that was failing is not anymore
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Summary
The SSE endpoint rewrite E2E tests (
proxy && sse && endpoint-rewrite) fail 100% of the time. They were orphaned from CI until the matrix rebalance (#4074), then had stale flags fixed (#4080), but have never actually passed. This PR fixes four root causes identified through local reproduction and log inspection.GenerateMCPServerURLomits/ssefor remote SSE URLs with no path, sowaitForInitializeSuccesssendsGET /instead ofGET /sse— the mock server returns 404, init retries for 5 min, and the test's 60s timeout expiresgetSSERewriteConfigreadsX-Forwarded-*headers from the outbound request, which has auto-injected values fromSetXForwarded(), converting relative endpoint URLs (/sse?sessionId=...) into absolute URLs with the proxy's own host — breaking test 3's assertionelseclause for non-/ssepaths (Go defaults to 200 OK), inconsistent with tests 1 and 2--endpoint-prefix) fails because the proxy doesn't strip the prefix from incoming requests (Strip endpointPrefix from request paths in transparent proxy #3372); skipped with a reference to the tracking issueType of change
Test plan
task test)task lint-fix)Changes
pkg/transport/url.go/ssepath for remote SSE URLs with empty pathpkg/transport/url_test.go/ssepkg/transport/proxy/transparent/sse_response_processor.gopkg/transport/proxy/transparent/transparent_proxy.goRewritepkg/transport/proxy/transparent/transparent_test.goTestGetSSERewriteConfigto pass inbound request via contexttest/e2e/sse_endpoint_rewrite_test.goSpecial notes for reviewers
The core issue with Bug 3 is subtle:
httputil.ReverseProxy.Rewritecallspr.SetXForwarded()which writesX-Forwarded-Host,X-Forwarded-Proto, etc. ontopr.Out. Then inModifyResponse,resp.Requestispr.Out— sogetSSERewriteConfigwas reading the proxy's own auto-injected headers rather than the client's original headers. The fix stashespr.In(the original inbound request) in the outbound request's context so the response processor can read the real client headers.Test 4 is skipped rather than fixed because the underlying issue (#3372 — endpoint prefix stripping for incoming requests) requires a separate design decision.
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