kahlan-config.travis.php

<?php
use Kahlan\Filter\Filter;
use Kahlan\Reporter\Coverage\Exporter\Coveralls;

$commandLine = $this->commandLine();
$commandLine->option('coverage', 'default', 3);

Filter::register('kahlan.coverage-exporter', function($chain) {
    $reporter = $this->reporters()->get('coverage');
    if (!$reporter) {
        return;
    }
    Coveralls::write([
        'collector'      => $reporter,
        'file'           => 'coveralls.json',
        'service_name'   => 'travis-ci',
        'service_job_id' => getenv('TRAVIS_JOB_ID') ?: null
    ]);
    return $chain->next();
});

Filter::apply($this, 'reporting', 'kahlan.coverage-exporter');