Simple Gulpfile that implements Jest. Context is a small Express app written in Coffeescript. The coffeescript is transpiled to JS, and then Jest is run on the result.

simple_jest_coffeescript_gulpfile.js

var gulp = require('gulp');
var coffee = require('gulp-coffee');
var header = require('gulp-header');
var pkg = require('./package.json');
var info = '//===========================\n// <%= pkg.name %>\n// @v<%= pkg.version %>, <%= pkg.license %>\n// <%= pkg.author %>\n//===========================\n';
var jest = require('jest-cli');
var gutil = require('gulp-util');
var through = require('through2');


// Simple setup without watchers - use 'watch' instead if needed
gulp.task('default', ['jest']);


// Run unit tests with jest after a full compile - outputs to a coverage directory
gulp.task('jest', ['compile'], function () {
  return gulp.src(['build'])
    .pipe(
      through.obj(function (file, enc, cb) {
        options = {
          testDirectoryName: "__tests__",
          testPathIgnorePatterns: [
            "node_modules",
            "src"
          ],
          collectCoverage: true,
          verbose: true,
          moduleFileExtensions: [
            "js"
          ]
        };
        options.rootDir = options.rootDir || file.path;
        jest.runCLI({
          config: options
        }, options.rootDir, function (success) {
          if(!success) {
            cb(new gutil.PluginError('gulp-jest', { message: "Tests Failed" }));
          } else {
            cb();
          }
        }.bind(this));
      })
    );
});



// Compiling regular code
gulp.task('compile', function(){
  return gulp.src(['src/**/*.coffee'])
    .pipe(coffee({bare: true}))
    .pipe(header(info, { pkg : pkg }))
    .pipe(gulp.dest('build'));
});