Jest Extension

@heilgar/pest-jest registers pest matchers with jest's expect.

Setup

npm install @heilgar/pest-jest @heilgar/pest-core

Option 1: Setup file

// jest.setup.ts
import { loadEnv } from "@heilgar/pest-core";
import { pestMatchers } from "@heilgar/pest-jest";

loadEnv();
expect.extend(pestMatchers);

// jest.config.json
{
  "setupFiles": ["./jest.setup.ts"]
}

Option 2: Per-file

import { loadEnv } from "@heilgar/pest-core";
import { pestMatchers } from "@heilgar/pest-jest";

loadEnv();
expect.extend(pestMatchers);

TypeScript

Add type declarations to your tsconfig.json:

{
  "compilerOptions": {
    "types": ["@heilgar/pest-jest"]
  }
}

This extends jest's Matchers interface so expect(res).toContainToolCall(...) has full type support.

Usage

Once registered, all pest matchers are available on expect():

import { send, createProvider } from "@heilgar/pest-core";

const provider = createProvider({
  name: "gpt4o",
  type: "openai",
  model: "gpt-4o",
});

describe("flight booking agent", () => {
  test("calls search tool for flight queries", async () => {
    const res = await send(provider, "Find flights to Paris tomorrow", {
      tools: flightTools,
    });

    expect(res).toContainToolCall("search_flights", {
      destination: "Paris",
    });
  });

  test("responds with relevant information", async () => {
    const res = await send(provider, "What is the capital of France?");

    expect(res).toMatchSemanticMeaning("Paris is the capital of France");
  });
});

Differences from Vitest Extension

The API is identical. The only differences are:

• Import source: @heilgar/pest-jest instead of @heilgar/pest-vitest
• Setup mechanism: jest's setupFilesAfterFramework vs vitest's setupFiles
• Type declarations: extends jest.Matchers instead of vitest's Assertion

Available Matchers

See Matchers for the full list. All matchers listed there are available after expect.extend(pestMatchers).