vercel__chat/packages/tests

@chat-adapter/tests

npm package: @chat-adapter/tests

Vitest factories, matchers, and setup utilities for testing Chat SDK adapters and bots.

Installation

pnpm add -D @chat-adapter/tests

This package has chat and vitest as peer dependencies — they should already be in your project.

Factories

import {
  createMockAdapter,
  createMockChatInstance,
  createMockState,
  createTestMessage,
  mockLogger,
} from "@chat-adapter/tests";

createMockAdapter(name?, overrides?)

Returns an Adapter with every method as vi.fn() and sensible defaults. Pass overrides to swap individual methods:

const adapter = createMockAdapter("slack", {
  postMessage: vi.fn().mockResolvedValue({ id: "msg-7", raw: {} }),
});

createMockState()

Returns a StateAdapter backed by in-memory Maps — subscriptions, locks, KV, lists, and queues all work end-to-end. Includes a cache: Map<string, unknown> for direct inspection.

createMockChatInstance(options?)

Returns a ChatInstance with every process* handler as vi.fn(). Useful for adapter authors verifying their adapter dispatches incoming events through the right hook.

const state = createMockState();
const chat = createMockChatInstance({ state });
await myAdapter.handleWebhook(req); // your adapter under test
expect(chat.processMessage).toHaveBeenCalledOnce();

createTestMessage(id, text, overrides?)

Builds a Message with parsed markdown AST already wired up.

mockLogger / createMockLogger()

mockLogger is a shared Logger for tests that don't care about isolation. createMockLogger() returns a fresh one per call.

Matchers

Vitest custom matchers covering the most common Chat SDK assertions.

Auto-register via setup file

// vitest.config.ts
import { defineConfig } from "vitest/config";

export default defineConfig({
  test: {
    setupFiles: ["@chat-adapter/tests/setup"],
  },
});

Manual registration

import { matchers } from "@chat-adapter/tests/matchers";
expect.extend(matchers);

Available matchers

Matcher	Asserts
expect(adapter).toHavePosted(threadId, textPattern?)	adapter.postMessage was called for this thread (and message text matches textPattern if given)
expect(adapter).toHaveEdited(threadId, messageId, textPattern?)	adapter.editMessage was called for this message (and text matches textPattern if given)
expect(adapter).toHaveDeleted(threadId, messageId)	adapter.deleteMessage was called for this message
expect(adapter).toHaveReactedWith(threadId, messageId, emoji)	adapter.addReaction was called with the emoji (string or EmojiValue.name)
expect(adapter).toHaveStartedTyping(threadId)	adapter.startTyping was called for this thread
expect(adapter).toHavePostedToChannel(channelId, textPattern?)	adapter.postChannelMessage was called for this channel
expect(chat).toHaveDispatched(handler)	The named process* handler on the mock ChatInstance was called
expect(state).toBeSubscribedTo(threadId)	state.isSubscribed(threadId) resolves to true (async — needs await)

expect(adapter).toHavePosted("slack:C1:t1", /hello/);
expect(adapter).toHaveEdited("slack:C1:t1", "msg-1", /updated/);
expect(adapter).toHaveDeleted("slack:C1:t1", "msg-1");
expect(adapter).toHaveReactedWith("slack:C1:t1", "msg-1", "thumbsup");
expect(adapter).toHaveStartedTyping("slack:C1:t1");
expect(adapter).toHavePostedToChannel("slack:C1");
expect(chat).toHaveDispatched("processMessage");
await expect(state).toBeSubscribedTo("slack:C1:t1");

Text-pattern matchers (toHavePosted, toHaveEdited, toHavePostedToChannel) extract a comparable string from AdapterPostableMessage — handling plain strings, PostableMarkdown.markdown, PostableRaw.raw, and PostableCard.fallbackText. AST-shaped messages (PostableAst) and cards without fallbackText aren't text-matchable; assert without textPattern and inspect mock.calls directly for deeper checks.

Audience

• Bot authors — drive simulated events through your handlers, assert on outbound calls.
• Adapter authors — verify your Adapter implementation routes webhooks through the right ChatInstance.process* hook with the right normalized payload.

Adapter-specific helpers (e.g. signed Slack webhook builders, Teams claim builders) live in each adapter's own /testing subpath, not in this kit.

AI Coding Agents

If you use an AI coding agent such as OpenAI Codex, Claude Code, or Cursor, install the Chat SDK skill so it knows the SDK APIs, adapter patterns, and project conventions before writing code.

npx skills add vercel/chat

The skill references bundled documentation in node_modules/chat/docs, plus adapter guides and starter templates in the published package.

You can also install the Vercel Plugin for a broader agent toolkit — it includes the Chat SDK skill alongside specialist agents, agent slash commands, and more:

npx plugins add vercel/vercel-plugin

The plugin is optional; the skill alone is enough to build with Chat SDK.

For agent-readable documentation, see chat-sdk.dev/llms.txt (page index) or chat-sdk.dev/llms-full.txt (full text).

License

MIT