Sample

Handle shelf request URL parsing, subpath rewrites with change, single-subscription body buffering, and pipeline error handling

sha256:8b87dbe3a6d2ab33ba4b807d61e35686efe22f1481d942766d8e1190783f14fe

Case

Goal

Handle shelf request URL parsing, subpath rewrites with change, single-subscription body buffering, and pipeline error handling HOW

Packages

shelf 1.4.2

Environment

dart

Created

2026-08-16T12:20:28Z

Commonly assumed

A shelf Request's url property is an absolute Uri whose path starts with a leading slash matching requestedUri.path, and change(path:) appends subpaths.

The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.

Contract

• assert request.url is a relative Uri with no scheme, host, or leading slash, that handlerPath defaults to '/', that requestedUri.path equals handlerPath + url.path, that change(path:) consumes path segments from url.path into handlerPath rather than appending, that change(path:) with a leading slash or unmatched prefix throws ArgumentError, and that Request constructor rejects a non-empty handlerPath missing a trailing slash
• assert reading a request body with readAsString drains the single-subscription Body stream so a second read throws StateError synchronously, that Request.change without body preserves the drained body so downstream handlers fail, and that passing body to change restores a fresh readable stream
• assert createMiddleware requestHandler short-circuit passes the response through its own responseHandler, that an exception caught by errorHandler does not run responseHandler on the error response, and that HijackException bypasses errorHandler completely to unwind the call stack
• assert Cascade dispatches to subsequent handlers on matching 404 status codes, but returns a 500 response immediately without cascading
• assert Response headers are case-insensitive on lookup while preserving original key casing in keys, and that string bodies automatically populate content-type and content-length whereas stream bodies do not

Files

• NOTES.md
• csx.json
• pubspec.lock
• pubspec.yaml
• test/contract.dart

Download the verified artifact (tar.gz) — the exact bytes the contract ran against

Origin Seeder

csx-seed

Verification receipts

• dart 3 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · pub@1 · 2026-08-16 · ed25519:d91480838ac982c9