[go-while]

Item 4 of survey-pynntp.md: the fake server as a program, so test suites in other languages can use the kit. It generalises pynntp's fault server (tests/faults/server/main.go in greenbender/pynntp#145, which drives 228 fault scenarios from Python) and leaves room for go-pugleaf's planned nntp-fakepeer (survey-go-pugleaf.md section 3): its peer mode is PeerOptions from JSON.

Usage

nntp-fakeserver [-listen host:port] config.json

• When listening, it prints one JSON line, {"addr","host","port","ca"}. ca is the PEM of a fresh self-signed certificate (tlscert.GenerateSelfSigned, tlscert, fakeserver: twins without testing.TB #9), valid for localhost, 127.0.0.1 and ::1. Clients verify implicit TLS and STARTTLS against it.
• It serves until stdin reaches EOF (or SIGINT/SIGTERM). Then it prints one summary line, {lines, mismatches, articles, notes, accepted, counts, tls_handshakes, tls_failed, server_names}, removes its temp dir and exits 0.
• Exit codes: 2 for a bad config or flag, 1 for another failure.

The full description, with an example for each mode, is in the package doc. README is left for the release.

Config

• Keys are the kit's Go field names (Options, StoreOpts, Faults, PeerOptions, Script, …). The decoder walks the kit types by reflection, so a new kit field, such as the Faults fields in the faults-bytes branch, works from JSON with no change here. TestEveryKitFieldDecodes fails if a new field has a shape it can't read.
• Durations are milliseconds.
• Errors: an unknown key is an error that names its path and lists the valid keys. So is a part the mode doesn't use.
• Not settable from JSON: functions, channels and Options.Store.
• TLS: Options.TLS: true means implicit TLS with the program's certificate. StartTLS: {} (plus the knobs Refuse, HideCapability, AuthNeedsTLS, CloseAfterHandshake) offers STARTTLS with it.
• Modes:
  • store: Store, StoreOpts and Faults.
  • peer: PeerOptions.
  • script: Options.Script as fakeserver.Step.
  • raw: byte-exact scripts. Per step: an anchored regexp for the client line, an optional dot block, chunks as Text or B64 with Gap/Split/SplitGap, then close/rst/hang/starttls/inflate. starttls uses Conn.StartTLS. The kit's Script mode is text lines only, which is why raw stays a mode of its own.

Testing

• main_test.go drives run() in-process:
  • store with faults, STARTTLS and implicit TLS verified against the printed CA file;
  • peer (IHAVE);
  • script;
  • raw: split chunks, starttls then a command over TLS, rst, pipelined plaintext after STARTTLS;
  • config errors (unknown key, wrong mode part, bad JSON);
  • the summary fields;
  • every kit field decoding.
• On a test VM with Go 1.27.3: gofmt -l empty, go vet ./... clean, go test -race -count=1 ./... passes in all packages, and -count=5 passes for this package.
• The built binary was also driven from Python 3.13 with ssl.create_default_context(cafile=ca) and a stdin pipe: TLS verified, summary with tls_handshakes: 1, temp dir gone after exit.

Next on the pynntp side: #145 switches from its own server to this program.

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