node.js - 获取按持续时间排序的 Jest 测试

Question

我正在努力提高我们的 Jest 测试的性能，其中包含 4,000 多个测试。要查看单个测试持续时间，我使用 --verbose 标志。

是否有一种简单的方法来发现运行时间最长的测试，还是我必须滚动浏览整个输出？

Answer 1

你可以编写一个测试报告器并将其添加到reporters jest的配置。

./reporters/slow-test.js:

class JestSlowTestReporter {
  constructor(globalConfig, options) {
    this._globalConfig = globalConfig;
    this._options = options;
    this._slowTests = [];
  }

  onRunComplete() {
    console.log();
    this._slowTests.sort((a, b) => b.duration - a.duration);
    var rootPathRegex = new RegExp(`^${process.cwd()}`);
    var slowestTests = this._slowTests.slice(0, this._options.numTests || 10);
    var slowTestTime = this._slowTestTime(slowestTests);
    var allTestTime = this._allTestTime();
    var percentTime = (slowTestTime / allTestTime) * 100;

    console.log(
      `Top ${slowestTests.length} slowest examples (${slowTestTime / 1000} seconds,` +
        ` ${percentTime.toFixed(1)}% of total time):`
    );

    for (var i = 0; i < slowestTests.length; i++) {
      var duration = slowestTests[i].duration;
      var fullName = slowestTests[i].fullName;
      var filePath = slowestTests[i].filePath.replace(rootPathRegex, '.');

      console.log(`  ${fullName}`);
      console.log(`    ${duration / 1000} seconds ${filePath}`);
    }
    console.log();
  }

  onTestResult(test, testResult) {
    for (var i = 0; i < testResult.testResults.length; i++) {
      this._slowTests.push({
        duration: testResult.testResults[i].duration,
        fullName: testResult.testResults[i].fullName,
        filePath: testResult.testFilePath,
      });
    }
  }

  _slowTestTime(slowestTests) {
    var slowTestTime = 0;
    for (var i = 0; i < slowestTests.length; i++) {
      slowTestTime += slowestTests[i].duration;
    }
    return slowTestTime;
  }

  _allTestTime() {
    var allTestTime = 0;
    for (var i = 0; i < this._slowTests.length; i++) {
      allTestTime += this._slowTests[i].duration;
    }
    return allTestTime;
  }
}

module.exports = JestSlowTestReporter;

jest.config.js:

module.exports = {
  preset: 'ts-jest/presets/js-with-ts',
  reporters: ['default', ['<rootDir>/reporters/slow-test', { numTests: 3 }]],
};

numTests: 3 参数表示找到前 3 个最慢的测试用例。

index.test.js:

describe('find top slowest test', () => {
  test('should 1', (done) => {
    setTimeout(() => {
      expect(1 + 1).toBe(2);
      done();
    }, 1000);
  });
  test('should 2', (done) => {
    setTimeout(() => {
      expect(1 + 1).toBe(2);
      done();
    }, 1200);
  });
  test('should 3', (done) => {
    setTimeout(() => {
      expect(1 + 1).toBe(2);
      done();
    }, 100);
  });
});

测试结果:

 PASS  examples/find-top-slowest-test/index.test.js
  find top slowest test
    ✓ should 1 (1007 ms)
    ✓ should 2 (1201 ms)
    ✓ should 3 (103 ms)

Test Suites: 1 passed, 1 total
Tests:       3 passed, 3 total
Snapshots:   0 total
Time:        3.588 s, estimated 4 s
Ran all test suites matching /\/Users\/dulin\/workspace\/github.com\/mrdulin\/jest-v26-codelab\/examples\/find-top-slowest-test\/index.test.js/i.

Top 3 slowest examples (2.311 seconds, 100.0% of total time):
  find top slowest test should 2
    1.201 seconds ./examples/find-top-slowest-test/index.test.js
  find top slowest test should 1
    1.007 seconds ./examples/find-top-slowest-test/index.test.js
  find top slowest test should 3
    0.103 seconds ./examples/find-top-slowest-test/index.test.js