testing.chunks

In-process ASGI chunk capture for streaming-response assertions.

TestClient.request() joins every http.response.bodyASGI message into a single bufferedResponse, which is the right shape for ordinary handlers but erases the framing of a streaming response. For Stream / TemplateStream / Suspensethe boundaries between body messages are load-bearing — they are the difference between a progressive, shell-first render and a fully buffered one.

CapturedStreampreserves that framing: it records the ordered list of non-empty body chunks exactly as the ASGIsend()callable received them (one entry perhttp.response.bodymessage), so a test can assert that a response arrives as more than one chunk, that the shell bytes precede the deferred/streamed-block bytes, and that specific markers land in the expected chunk.

This is a socket-free counterpart to a real chunked-transfer client: the same send()messages an ASGI server would write to the wire, captured in memory. Real socket binding is unavailable in the CI sandbox, so structural and ordering assertions live here; wall-clock timing assertions do not (they need a socket and are flaky).