1// Copyright 2020 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5/**
6 * @fileoverview Test helpers.
7 */
8
9'use strict';
10
11const assert = require('assert');
12const path = require('path');
13const fs = require('fs');
14
15const sourceHelpers = require('../source_helpers.js');
16
17const BASE_DIR = path.join(path.dirname(__dirname), 'test_data');
18const DB_DIR = path.join(BASE_DIR, 'fake_db');
19
20const HEADER = `// Copyright 2020 the V8 project authors. All rights reserved.
21// Use of this source code is governed by a BSD-style license that can be
22// found in the LICENSE file.
23
24`;
25
26/**
27 * Create a function that returns one of `probs` when called. It rotates
28 * through the values. Useful to replace `random.random()` in tests using
29 * the probabilities that trigger different interesting cases.
30 */
31function cycleProbabilitiesFun(probs) {
32  let index = 0;
33  return () => {
34    index = index % probs.length;
35    return probs[index++];
36  };
37}
38
39/**
40 * Replace Math.random with a deterministic pseudo-random function.
41 */
42function deterministicRandom(sandbox) {
43    let seed = 1;
44    function random() {
45        const x = Math.sin(seed++) * 10000;
46        return x - Math.floor(x);
47    }
48    sandbox.stub(Math, 'random').callsFake(() => { return random(); });
49}
50
51function loadTestData(relPath) {
52  return sourceHelpers.loadSource(BASE_DIR, relPath);
53}
54
55function assertExpectedResult(expectedPath, result) {
56  const absPath = path.join(BASE_DIR, expectedPath);
57  if (process.env.GENERATE) {
58    fs.writeFileSync(absPath, HEADER + result.trim() + '\n');
59    return;
60  }
61
62  // Omit copyright header when comparing files.
63  const expected = fs.readFileSync(absPath, 'utf-8').trim().split('\n');
64  expected.splice(0, 4);
65  assert.strictEqual(expected.join('\n'), result.trim());
66}
67
68module.exports = {
69  BASE_DIR: BASE_DIR,
70  DB_DIR: DB_DIR,
71  assertExpectedResult: assertExpectedResult,
72  cycleProbabilitiesFun: cycleProbabilitiesFun,
73  deterministicRandom: deterministicRandom,
74  loadTestData: loadTestData,
75}
76