lcov-merger Gulp task

gulpfile.js

var gulp = require('gulp'),
  merger = require ('lcov-result-merger');

gulp.task('merge-coverage', function() {
  return gulp.src('./reports/coverage/**/lcov.info')
    .pipe(merger())
    .pipe(gulp.src('./reports/merged/'))
});

Line 7 should be .pipe(gulp.dest('./reports/merged/'))