The current code style and PHP compatibility setup is pretty out-of-date, inconsistent and convoluted:
The Travis script seems to try use your theme to unit test PHPCompatibility.
Honestly, you don't have to as PHPCompatibility does extensive unit testing itself.
Just run it once on a high PHP version with a properly set testVersion and you're done - or in case you want to test separately for compatibility with PHP 5.6 and above and compatibility with PHP 5.2/5.3-5.5, run it twice, but running it the way it's done now.... is really not very effective.
See: https://github.com/PHPCompatibility/PHPCompatibility#sniffing-your-code-for-compatibility-with-specific-php-versions
The Composer file is pointing to the abandoned wimg/php-compatibility repo.
The package was moved to phpcompatibility/php-compatibility a year ago....
squizlabs/php_codesniffer is not a direct dependency for your theme, but a dependency of PHPCompatibility(WP). Don't require it, but let the package which depends on it manage the supported versions.
You seem to include a codesniffer.ruleset.xml file, but don't require-dev the needed dependency (WPCS) for it.
The WPCS version which the ruleset seems to be based on is very much out of date and a number of sniffs have been renamed since. This ruleset will not work anymore.
The ruleset has a non-standard name which means that PHPCS will not pick up on it automatically.
Please consider renaming the file to phpcs.xml.dist.
The code is not actually checked against the ruleset via Travis anyway, so what is going on here ?
The current code style and PHP compatibility setup is pretty out-of-date, inconsistent and convoluted:
testVersionand you're done - or in case you want to test separately for compatibility with PHP 5.6 and above and compatibility with PHP 5.2/5.3-5.5, run it twice, but running it the way it's done now.... is really not very effective. See: https://github.com/PHPCompatibility/PHPCompatibility#sniffing-your-code-for-compatibility-with-specific-php-versionsPHPCompatibilityWPinstead ofPHPCompatibility. See: https://github.com/PHPCompatibility/PHPCompatibilityWPwimg/php-compatibilityrepo. The package was moved tophpcompatibility/php-compatibilitya year ago....squizlabs/php_codesnifferis not a direct dependency for your theme, but a dependency of PHPCompatibility(WP). Don'trequireit, but let the package which depends on it manage the supported versions.^0.5.0. Composer treats minors < 1.0 as majors, so this needs to be done explicitly. See: https://github.com/Dealerdirect/phpcodesniffer-composer-installer/releasescodesniffer.ruleset.xmlfile, but don'trequire-devthe needed dependency (WPCS) for it.phpcs.xml.dist.If this is truly intended as a starter-theme, I would strongly suggest leading by example and setting these things up properly and correctly.