Testing

@threadplane/ag-ui gives you two test doubles, smallest scope first:

• provideFakeAgent() — a one-call fake backend that runs the real adapter pipeline and streams canned tokens. No server, no LLM.
• mockAgent() (from @threadplane/chat) — a writable-signal mock for component/unit tests. The ag-ui agent is the neutral Agent contract, so there is no ag-ui-specific mock — use the neutral one directly.

See Choosing an adapter → Testing for when to use each test double.

#Fake backend: provideFakeAgent()

provideFakeAgent({ tokens, reasoningTokens, delayMs }) wires a fake backend into Angular DI in one call. It exercises the real adapter pipeline — injectAgent(), status transitions, message accumulation — but the wire events are canned, so there's no server and no LLM. Use it for adapter-integration tests, in-browser demos, and offline development.

It drops in exactly where provideAgent() would go — the call shape matches the LangGraph adapter:

import { ApplicationConfig } from '@angular/core';
import { provideFakeAgent } from '@threadplane/ag-ui';
 
export const appConfig: ApplicationConfig = {
  providers: [
    provideFakeAgent({ tokens: ['Hello'] }),
  ],
};

The component is byte-identical to production — only the provider changes. FakeAgentConfig ({ tokens?, reasoningTokens?, delayMs? }) lives in @threadplane/chat/testing:

For the underlying FakeAgent class and its canned event sequence, see Fake Agent.

#Contract mock: mockAgent()

For component and unit tests where you don't need a streaming pipeline at all, use the neutral mockAgent(initial) from @threadplane/chat. It returns an Agent whose state surface is exposed as writable signals — set state directly and assert your component reacts. Nothing is real.

The ag-ui adapter exposes exactly the neutral Agent contract, so there is no ag-ui-specific mock — mockAgent() is the right tool.

import { mockAgent } from '@threadplane/chat';
 
const m = mockAgent({ status: 'running' });
m.messages.set([{ role: 'assistant', content: 'Hello!' }]);
 
expect(m.messages()[0].content).toBe('Hello!');
expect(m.status()).toBe('running');