packages/runtime/src/__tests__/request-customization-fetch.test.ts

import assert from 'node:assert/strict';
import { describe, test } from 'node:test';
import { createRequestCustomizationFetch } from '../request-customization-fetch.js';

describe('createRequestCustomizationFetch', () => {
  test('applies generic headers and extra fields to a JSON POST request', async () => {
    const requests: Request[] = [];
    const fetch = createRequestCustomizationFetch(
      async (input, init) => {
        requests.push(new Request(input, init));
        return new Response('{}', { status: 200 });
      },
      {
        headers: { 'HTTP-Referer': 'https://maka.example', 'X-Title': 'Maka' },
        bodyOverlay: { provider: { order: ['Anthropic'], allow_fallbacks: false } },
      },
    );

    await fetch('https://openrouter.ai/api/v1/chat/completions', {
      method: 'POST',
      headers: { 'content-type': 'application/json' },
      body: JSON.stringify({ model: 'example/model', messages: [] }),
    });

    const request = requests[0];
    assert.ok(request);
    assert.equal(request.headers.get('http-referer'), 'https://maka.example');
    assert.equal(request.headers.get('x-title'), 'Maka');
    assert.deepEqual(await request.json(), {
      model: 'example/model',
      messages: [],
      provider: { order: ['Anthropic'], allow_fallbacks: false },
    });
  });

  test('adds headers to model discovery without adding a body', async () => {
    let captured: Request | undefined;
    const fetch = createRequestCustomizationFetch(
      async (input, init) => {
        captured = new Request(input, init);
        return new Response('{}', { status: 200 });
      },
      { headers: { 'X-Tenant': 'tenant-a' }, bodyOverlay: { provider: { sort: 'price' } } },
    );

    await fetch('https://openrouter.ai/api/v1/models');

    assert.equal(captured?.headers.get('x-tenant'), 'tenant-a');
    assert.equal(captured?.body, null);
  });

  test('passes URL and init across fetch implementations instead of a realm-specific Request', async () => {
    let captured: Request | undefined;
    const fetch = createRequestCustomizationFetch(
      async (input, init) => {
        assert.equal(typeof input, 'string');
        captured = new Request(input, init);
        return new Response('{}', { status: 200 });
      },
      { bodyOverlay: { provider: { only: ['deepseek'] } } },
    );

    await fetch('https://openrouter.ai/api/v1/chat/completions', {
      method: 'POST',
      headers: { 'content-type': 'application/json' },
      body: JSON.stringify({ model: 'example/model' }),
    });

    assert.deepEqual(await captured?.json(), {
      model: 'example/model',
      provider: { only: ['deepseek'] },
    });
  });

  test('rejects collisions instead of silently overriding generated request data', async () => {
    const fetch = createRequestCustomizationFetch(async () => new Response('{}', { status: 200 }), {
      headers: { 'X-Tenant': 'custom' },
      bodyOverlay: { model: 'other/model' },
    });

    await assert.rejects(
      fetch('https://example.test/chat/completions', {
        method: 'POST',
        headers: { 'content-type': 'application/json', 'x-tenant': 'generated' },
        body: JSON.stringify({ model: 'generated/model' }),
      }),
      /Custom request header conflicts/,
    );

    const bodyOnly = createRequestCustomizationFetch(
      async () => new Response('{}', { status: 200 }),
      { bodyOverlay: { model: 'other/model' } },
    );
    await assert.rejects(
      bodyOnly('https://example.test/responses', {
        method: 'POST',
        headers: { 'content-type': 'application/json' },
        body: JSON.stringify({ model: 'generated/model' }),
      }),
      /Extra request body conflicts/,
    );
  });
});