Vfrdtyky

I am working on gulp-mocha and gulp-Istanbul but when I run command gulp mocha
the error coming up to screen. I am a new with the gulp and trying build a unit test in my project

here is my gulpfile.babel.js

import gulp from 'gulp';

import gulpLoadPlugins from 'gulp-load-plugins';

import path from 'path';

import del from 'del';

import runSequence from 'run-sequence';

import babelCompiler from 'babel-core/register';

import * as isparta from 'isparta';

import babel from 'gulp-babel';



const plugins = gulpLoadPlugins();



const paths = {

  js: ['./**/*.js', '!dist/**', '!node_modules/**', '!coverage/**'],

  nonJs: ['./package.json', './.gitignore', './**/*.ejs'],

  tests: './server/tests/*.js'

};



const options = {

  codeCoverage: {

    reporters: ['lcov', 'text-summary'],

    thresholds: {

      global: {

        statements: 50, branches: 50, functions: 50, lines: 50

      }

    }

  }

};



// Clean up dist and coverage directory

gulp.task('clean', () =>

  del(['dist/**', 'coverage/**', '!dist', '!coverage']));



// Set env variables

gulp.task('set-env', () => {

  plugins.env({

    vars: {

      NODE_ENV: 'test'

    }

  });

});



// Lint Javascript

gulp.task('lint', () =>

  gulp.src(paths.js)

    // eslint() attaches the lint output to the "eslint" property

    // of the file object so it can be used by other modules.

    .pipe(plugins.eslint())

    // eslint.format() outputs the lint results to the console.

    // Alternatively use eslint.formatEach() (see Docs).

    .pipe(plugins.eslint.format())

    // To have the process exit with an error code (1) on

    // lint error, return the stream and pipe to failAfterError last.

    .pipe(plugins.eslint.failAfterError()));



// Copy non-js files to dist

gulp.task('copy', () =>

  gulp.src(paths.nonJs)

    .pipe(plugins.newer('dist'))

    .pipe(gulp.dest('dist')));



// Compile ES6 to ES5 and copy to dist

gulp.task('babel', () =>

  gulp.src([...paths.js, '!gulpfile.babel.js'], { base: '.' })

    .pipe(plugins.newer('dist'))

    .pipe(plugins.sourcemaps.init())

    .pipe(babel())

    .pipe(plugins.sourcemaps.write('.', {

      includeContent: false,

      sourceRoot(file) {

        return path.relative(file.path, __dirname);

      }

    }))

    .pipe(gulp.dest('dist')));



// Start server with restart on file changes

gulp.task('nodemon', ['copy', 'babel'], () =>

  plugins.nodemon({

    script: path.join('dist', 'index.js'),

    ext: 'js',

    ignore: ['node_modules/**/*.js', 'dist/**/*.js'],

    tasks: ['copy', 'babel']

  }));



// covers files for code coverage

gulp.task('pre-test', () =>

  gulp.src([...paths.js, '!gulpfile.babel.js'])

    // Covering files

    .pipe(plugins.istanbul({

      instrumenter: isparta.Instrumenter,

      includeUntested: true

    }))

    // Force `require` to return covered files

    .pipe(plugins.istanbul.hookRequire()));



// triggers mocha test with code coverage

gulp.task('test', ['pre-test', 'set-env'], () => {

  let reporters;

  let exitCode = 0;

  if (plugins.util.env['code-coverage-reporter']) {

    reporters = [...options.codeCoverage.reporters, plugins.util.env['code-coverage-reporter']];

  } else {

    reporters = options.codeCoverage.reporters;

  }



  return gulp.src([paths.tests], { read: false })

    .pipe(plugins.plumber())

    .pipe(plugins.mocha({

      reporter: plugins.util.env['mocha-reporter'] || 'spec',

      ui: 'bdd',

      timeout: 11000,

      compilers: {

        js: babelCompiler,

      }

    }))

    .once('error', (err) => {

      plugins.util.log(err);

      exitCode = 1;

    })

    // Creating the reports after execution of test cases

    .pipe(plugins.istanbul.writeReports({

      dir: './coverage',

      reporters,

    }))

    // Enforce test coverage

    .pipe(plugins.istanbul.enforceThresholds({

      thresholds: options.codeCoverage.thresholds,

    }))

    .once('end', () => {

      plugins.util.log('completed !!');

      process.exit(exitCode);

    });

});



// clean dist, compile js files, copy non-js files and execute tests

gulp.task('mocha', ['clean'], () => {

  runSequence(

    ['copy', 'babel'],

    'test',

  );

});



// gulp serve for development

gulp.task('serve', ['clean'], () => runSequence('nodemon'));



// default task: clean dist, compile js files and copy non-js files.

gulp.task('default', ['clean'], () => {

  runSequence(['copy', 'babel']);

});

and here is the error I am facing

I don't know why the error happens to me, can anyone suggest me a solution to fix this bug or explain why this happen