Sample

Stub HTTP responses for Elixir code that uses Req, with no network, no fake server process and no mocking library

sha256:1a5be8dc134928a8238887f9504e70f60f67fb5fa956fd3fc577d86784ecfa1d

Case

Goal

Stub HTTP responses for Elixir code that uses Req, with no network, no fake server process and no mocking library HOW

Packages

req 0.7.2 plug 1.20.3 jason 1.4.5

Environment

elixir 1

Created

2026-08-14T20:15:02Z

Contract

• assert the response content-type is what decodes the body, so a stub built with Req.Test.json hands the caller a map and no .json() accessor is called anywhere, and that headers are a map of lists where a missing header reads as nil
• assert the same JSON bytes sent with Plug.Conn.send_resp and no content-type stay a binary, so a clean HTTP 200 stops matching the caller's %{"celsius" => _} clause
• assert that with no content-type the request URL path decides instead: /data.json is decoded while /data and /data.txt are not, because decode_body falls back to application/octet-stream and resolves that through MIME.from_path
• assert an HTTP 500 is {:ok, response} and raises from neither Req.request/1 nor Req.request!/1, that the error body is decoded like any other body, and that http_errors: :raise reports the body still undecoded because handle_http_errors runs ahead of decode_body
• assert retry is on by default: one 500 on GET calls the stub four times (the initial request plus max_retries 3), the same 500 on POST calls it once because :safe_transient covers GET and HEAD only, and retry: :transient opts POST in
• assert Req.Test.transport_error produces {:error, %Req.TransportError{}} rather than a response, which a queue of canned responses cannot express, and that Req.get! raises it
• assert expectations are consumed in order ahead of a stub whatever the registration order, and that once drained Req.Test falls through to the stub instead of failing
• assert an exhausted expectation with no stub raises "no mock or stub for X" while a name never registered raises the different "cannot find mock/stub X in process #PID<...>"
• assert an unmet expectation fails nothing until Req.Test.verify! is called, and that verify! then names how many more uses were expected
• assert JSON decoding is switched off by decode_body: false, decoders: false or raw: true, that :decoders replaces the default [:json, :json_api] rather than extending it, and that a codec under :decoders is the 0.7.0 replacement for the deprecated :decode_json
• assert Req.Test implements the Plug behaviour and the stub name is literally that plug's options, so a bare function plug stubs HTTP with no registry at all

Files

• csx.json
• lib/csx_req/weather.ex
• mix.exs
• mix.lock
• test/contract_test.exs
• test/test_helper.exs

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

Origin Seeder

anonymous

Verification receipts

• elixir 1 · CONTAINER_RUN · compile:PASS · contract:PASS · load:PASS · resolve:PASS · hex@1 · 2026-08-14 · ed25519:a2ec939a4c60e243