Lite Agent
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      • Testing utilities

      The kernel is testable without any network access. @lite-agent/core ships a scripted ModelProvider test double (fakeProvider) so agent-loop tests are deterministic, plus two conformance suites — providerConformance and checkpointerConformance — that validate any custom strategy implementation against the exact contract the kernel relies on. If you write your own provider or persistence backend, running these suites is the cheapest way to know you got the contract right.

      Scripting a model with fakeProvider

      fakeProvider(turns) replays scripted FakeTurns ({ text?, message, usage? }) in order — deterministic, no network. Use it to drive the full kernel loop in a unit test:

      import { createAgent, nativeCodec, fakeProvider, textBlock } from "@lite-agent/core";

const agent = createAgent({
  model: fakeProvider([
    { text: "hi", message: { role: "assistant", content: [textBlock("hi")] } },
  ]),
  codec: nativeCodec(),
});

const result = await agent.send("hello");
console.log(result.text); // "hi"

      Each scripted turn can carry text, a complete assistant message (including tool_call blocks, to exercise the tool phase), and a usage record. Because fakeProvider is a real ModelProvider, everything around it — middleware, codecs, checkpointers, permission gates — runs exactly as in production.

      providerConformance

      An array of named test cases that any ModelProvider must pass: text-delta ordering, a single terminal message_done, error mapping to ProviderError, and abort handling. Feed it a ProviderConformanceFactory that builds your provider for each ProviderConformanceScenario:

      import { providerConformance } from "@lite-agent/core";

for (const test of providerConformance) {
  it(test.name, () => test.run((scenario) => makeMyProvider(scenario)));
}

      The maintained anthropic() and openai() adapters pass this suite offline, via their injected-client seam.

      checkpointerConformance

      The same idea for Checkpointer backends: monotonic seq, sinceSeq replay, conflict rejection (CheckpointConflictError on a stale expectedHead), list/delete, serialized concurrent appends, and payload round-trip:

      import { checkpointerConformance } from "@lite-agent/core";

for (const test of checkpointerConformance) {
  it(test.name, () => test.run(() => myCheckpointer()));
}

      The SQLite backend validates itself against this suite — the same one the SDK's default fileCheckpointer runs against. Run it against your own backend before trusting it with real sessions.

      See also