tears.js

      var watcher = options.watcher;
      var started = false;
      var builder = watcher.builder;
      var oldBuild = builder.build;

      builder.build = function(){
        return this.pausePromise.then(function(){
          return oldBuild.apply(this);
        }.bind(this));
      };

      //builder.build = require('lodash.debounce')(builder.build, 300);

      builder.pausePromise = Promise.resolve();

      watcher.on('error', function(err){
        ui.write('oops', err);
        ui.write('oops', err.message);
        process.exit(1);
      });

      function restart(){
        var once = require('lodash.once');
        builder.pausePromise = new Promise(function(resolve, reject){
          testem.app.startTests(function(){
            testem.app.on('all-runners-complete', once(resolve));
          });
        });
      }

      require('osx-ulimit').set(4096);
      var restartTestem = require('lodash.throttle')(restart, 300);

      // Wait for a build and then either start or restart testem
      watcher.on('change', function() {
        if (started) {
          restartTestem();
        } else {
          started = true;

          ui.pleasantProgress.stop();

          testem.startDev(testemOptions, function(code) {
            rimraf(options.outputPath)
              .finally(function() {
                process.exit(code);
              });
          });
        }
      });
    }).catch(function(err){