reportFinish(
    hasError: boolean,
    errors: { [fileName: string]: ErrorMessage; }
  ): void {
    Object
      .keys(errors)
      .map(fileName => [fileName, errors[fileName]])
      .forEach(([fileName, errorMessage], index) => {
        console.log(`${red('✗ failure: ')}${fileName}`);
        console.log(errorMessage);
      });

    // assert this.totalFileNum === [totalFileNum in reportFileNumber];
    const totalFileNum = this.totalFileNum;
    // assert this.failedFileNum === Object.keys(errors).length;
    const failedFileNum = this.failedFileNum;
    // assert this.succeedFileNum === totalFileNum - failedFileNum;
    // const succeedFileNum = this.succeedFileNum; // unused
    const totalTestNum = this.totalTestNum;
    const failedTestNum = this.failedTestNum;
    // const succeedTestNum = this.succeedTestNum; // unused
    const summary = hasError
      ? red(
        `✗ ${failedFileNum} of ${totalFileNum} files` +
        `, ${failedTestNum} of ${totalTestNum} tests failed`
      )
      : green(`✓ ${totalFileNum} files ${totalTestNum} tests completed`);
    console.log(summary);
  }

  finished(results: TestResult[]): void {
    const passed = results.filter(({ error }) => !!!error);
    const failed = results.filter(({ error }) => !!error);

    failed.forEach(({ test, error: { name, message } }) => {
      console.log(`${red(x + ' failure: ')}${test.name}`);
      console.log(`${name}: ${message}`);
    });

    const summary = failed.length > 0
      ? red(x + ` ${failed.length} of ${results.length} tests failed`)
      : green(v + ` ${results.length} tests passed`);
    console.log(summary);
  }

  reportSuccess(fileName: TestName) {
    this.totalFileNum += 1;
    this.succeedFileNum += 1;

    console.log(`${green('✓ success: ')}${fileName}`);
  }

 testFinished(result: TestResult): void {
   if (!!result.error) return;
   console.log(`${green(v + ' success: ')}${result.test.name}`);
 }