ai-code-review/app/test/llm.test.js

import { describe, it, beforeEach, afterEach, mock } from 'node:test';
import assert from 'node:assert/strict';
import axios from 'axios';
import { extractBalancedJSON, extractJSONText } from '../llm.js';

const ENV_KEYS = [
  'OPENCODE_BASE_URL', 'OPENCODE_MODEL', 'OPENCODE_PROVIDER',
];

let saved = {};
beforeEach(() => {
  saved = {};
  for (const k of ENV_KEYS) { saved[k] = process.env[k]; delete process.env[k]; }
});
afterEach(() => {
  for (const k of ENV_KEYS) {
    if (saved[k] === undefined) delete process.env[k];
    else process.env[k] = saved[k];
  }
  mock.restoreAll();
});

function mockOpenCodeResponse(content) {
  let calls = 0;
  mock.method(axios, 'post', async () => {
    calls += 1;
    if (calls === 1) return { data: { id: 'ses_test' } };
    return { data: { parts: [{ type: 'text', text: content }] } };
  });
}

describe('chat - OpenCode', async () => {
  const { chat } = await import('../llm.js');

  it('uses OpenCode server session API', async () => {
    process.env.OPENCODE_BASE_URL = 'http://opencode.local:4096';
    process.env.OPENCODE_PROVIDER = 'google';
    process.env.OPENCODE_MODEL = 'gemini-2.5-flash';
    const calls = [];
    mock.method(axios, 'post', async (url, payload, opts) => {
      calls.push({ url, payload, headers: opts.headers });
      if (url.endsWith('/session')) return { data: { id: 'ses_test' } };
      return { data: { parts: [{ type: 'text', text: 'opencode response' }] } };
    });

    const result = await chat('sys', 'user');

    assert.equal(result, 'opencode response');
    assert.equal(calls[0].url, 'http://opencode.local:4096/session');
    assert.deepEqual(calls[0].payload.model, { providerID: 'google', id: 'gemini-2.5-flash' });
    assert.equal(calls[1].url, 'http://opencode.local:4096/session/ses_test/message');
    assert.deepEqual(calls[1].payload.model, { providerID: 'google', modelID: 'gemini-2.5-flash' });
    assert.equal(calls[1].payload.system, 'sys');
    assert.deepEqual(calls[1].payload.parts, [{ type: 'text', text: 'user' }]);
    assert.equal(calls[1].headers['Authorization'], undefined);
  });

  it('passes an insecure https agent to OpenCode by default', async () => {
    process.env.OPENCODE_BASE_URL = 'https://opencode.local:4096';
    const agents = [];
    mock.method(axios, 'post', async (url, _payload, opts) => {
      agents.push(opts.httpsAgent);
      if (url.endsWith('/session')) return { data: { id: 'ses_test' } };
      return { data: { parts: [{ type: 'text', text: 'ok' }] } };
    });

    await chat('sys', 'user');

    assert.equal(agents.length, 2);
    assert.equal(agents[0].options.rejectUnauthorized, false);
    assert.equal(agents[1].options.rejectUnauthorized, false);
  });

  it('extracts text from OpenCode message parts', async () => {
    process.env.OPENCODE_BASE_URL = 'http://opencode.local:4096';
    let calls = 0;
    mock.method(axios, 'post', async () => {
      calls += 1;
      if (calls === 1) return { data: { id: 'ses_test' } };
      return { data: { parts: [{ type: 'text', text: 'hello' }, { type: 'text', text: ' world' }] } };
    });

    const result = await chat('sys', 'user');

    assert.equal(result, 'hello world');
  });

  it('throws an error when OpenCode fails instead of exiting the process', async () => {
    process.env.OPENCODE_BASE_URL = 'http://opencode.local:4096';
    mock.method(axios, 'post', async () => {
      const err = new Error('Request failed with status code 500');
      err.response = { status: 500, data: { error: 'provider overloaded' } };
      throw err;
    });
    const exitMock = mock.method(process, 'exit', () => { throw new Error('exit should not be called'); });

    await assert.rejects(() => chat('sys', 'user'), /HTTP 500.*provider overloaded/);

    assert.equal(exitMock.mock.calls.length, 0);
  });
});

describe('chatJSON', async () => {
  const { chatJSON } = await import('../llm.js');

  it('parses plain JSON response', async () => {
    process.env.OPENCODE_BASE_URL = 'http://opencode.local:4096';
    mockOpenCodeResponse('[{"level":"critical"}]');

    const result = await chatJSON('sys', 'user');

    assert.deepEqual(result, [{ level: 'critical' }]);
  });

  it('strips markdown code block before parsing', async () => {
    process.env.OPENCODE_BASE_URL = 'http://opencode.local:4096';
    mockOpenCodeResponse('```json\n[{"level":"info"}]\n```');

    const result = await chatJSON('sys', 'user');

    assert.deepEqual(result, [{ level: 'info' }]);
  });

  it('extracts JSON array from surrounding prose', async () => {
    process.env.OPENCODE_BASE_URL = 'http://opencode.local:4096';
    mockOpenCodeResponse('**Reviewing findings**\n\n[{"level":"warning","suggestion":"x"}]\n\nDone.');

    const result = await chatJSON('sys', 'user');

    assert.deepEqual(result, [{ level: 'warning', suggestion: 'x' }]);
  });

  it('extracts JSON object from surrounding prose', async () => {
    process.env.OPENCODE_BASE_URL = 'http://opencode.local:4096';
    mockOpenCodeResponse('**Begin Combine**\n{"merged_text":"repo block\\n\\nsource block"}');

    const result = await chatJSON('sys', 'user');

    assert.deepEqual(result, { merged_text: 'repo block\n\nsource block' });
  });

  it('returns [] when JSON is invalid', async () => {
    process.env.OPENCODE_BASE_URL = 'http://opencode.local:4096';
    mockOpenCodeResponse('not json');

    const result = await chatJSON('sys', 'user');

    assert.deepEqual(result, []);
  });
});

describe('extractBalancedJSON', () => {
  it('returns the whole object for a simple object from index 0', () => {
    const text = '{"a":1}';

    assert.equal(extractBalancedJSON(text, 0), '{"a":1}');
  });

  it('returns the full balanced segment for deeply nested object/array', () => {
    const text = '{"a":[1,{"b":[2,{"c":3}]}],"d":4}';

    assert.equal(extractBalancedJSON(text, 0), '{"a":[1,{"b":[2,{"c":3}]}],"d":4}');
  });

  it('does not let braces inside a string value break balancing', () => {
    const text = '{"a":"}{"}';

    assert.equal(extractBalancedJSON(text, 0), '{"a":"}{"}');
  });

  it('handles an escaped quote inside a string value', () => {
    const text = '{"a":"\\""}';

    assert.equal(extractBalancedJSON(text, 0), '{"a":"\\""}');
  });

  it('returns null for truncated/incomplete JSON', () => {
    const text = '{"a":1';

    assert.equal(extractBalancedJSON(text, 0), null);
  });

  it('extracts a balanced array when starting at a "["', () => {
    const text = '[1,[2,3],{"a":4}]';

    assert.equal(extractBalancedJSON(text, 0), '[1,[2,3],{"a":4}]');
  });

  it('excludes trailing content after the balanced segment', () => {
    const text = '{"a":1} trailing text {"b":2}';

    assert.equal(extractBalancedJSON(text, 0), '{"a":1}');
  });
});

describe('extractJSONText', () => {
  it('strips a fenced ```json block', () => {
    const text = '```json\n{"a":1}\n```';

    const result = extractJSONText(text);

    assert.deepEqual(JSON.parse(result), { a: 1 });
  });

  it('extracts a JSON object after leading prose', () => {
    const text = 'Here are the findings:\n{"level":"critical"}';

    const result = extractJSONText(text);

    assert.deepEqual(JSON.parse(result), { level: 'critical' });
  });

  it('extracts an array embedded in surrounding text', () => {
    const text = 'prefix [1,2,3] suffix';

    const result = extractJSONText(text);

    assert.deepEqual(JSON.parse(result), [1, 2, 3]);
  });

  it('returns an already-pure JSON string as-is', () => {
    const text = '{"a":1,"b":[2,3]}';

    const result = extractJSONText(text);

    assert.equal(result, '{"a":1,"b":[2,3]}');
    assert.deepEqual(JSON.parse(result), { a: 1, b: [2, 3] });
  });

  it('returns the de-fenced original text when no valid JSON is found', () => {
    const text = '```\nnot json at all\n```';

    const result = extractJSONText(text);

    assert.equal(result, 'not json at all');
  });
});