Run codesniffer only on pull requests

bin/phpcs.ruleset.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0"?>
+<ruleset name="WordPress Coding Standards for Plugins">
+    <description>Generally-applicable sniffs for WordPress plugins</description>
+
+    <rule ref="WordPress-Extra" />
+
+    <exclude-pattern>/tests/*,/vendor/*</exclude-pattern>
+
+</ruleset>

bin/prepare.sh

@@ -0,0 +1,14 @@
+#!/bin/bash
+
+PLUGIN_DIR=$(pwd)
+PHPCS_GITHUB_SRC=squizlabs/PHP_CodeSniffer
+PHPCS_GIT_TREE=master
+PHPCS_IGNORE="$TRAVIS_BUILD_DIR/tests,$TRAVIS_BUILD_DIR/vendor,$TRAVIS_BUILD_DIR/bin,$TRAVIS_BUILD_DIR/assets*,$TRAVIS_BUILD_DIR/languages,$TRAVIS_BUILD_DIR/node_modules,$TRAVIS_BUILD_DIR/readme"
+echo "PHPCS_IGNORE: $PHPCS_IGNORE"
+WPCS_DIR=/tmp/wpcs
+WPCS_GITHUB_SRC=WordPress-Coding-Standards/WordPress-Coding-Standards
+WPCS_GIT_TREE=develop
+
+mkdir -p $PHPCS_DIR && curl -L https://github.com/$PHPCS_GITHUB_SRC/archive/$PHPCS_GIT_TREE.tar.gz | tar xvz --strip-components=1 -C $PHPCS_DIR
+mkdir -p $WPCS_DIR && curl -L https://github.com/$WPCS_GITHUB_SRC/archive/$WPCS_GIT_TREE.tar.gz | tar xvz --strip-components=1 -C $WPCS_DIR
+$PHPCS_DIR/scripts/phpcs --config-set installed_paths $WPCS_DIR