MySQL version switching with MySQL Sandbox

wp-tests-config.php

<?php

/* Path to the WordPress codebase you'd like to test. Add a backslash in the end. */
define( 'ABSPATH', dirname( __FILE__ ) . '/src/' );

// Test with multisite enabled.
// Alternatively, use the tests/phpunit/multisite.xml configuration file.
// define( 'WP_TESTS_MULTISITE', true );

// Force known bugs to be run.
// Tests with an associated Trac ticket that is still open are normally skipped.
// define( 'WP_TESTS_FORCE_KNOWN_BUGS', true );

// Test with WordPress debug mode (default).
define( 'WP_DEBUG', true );

// ** MySQL settings ** //

// This configuration file will be used by the copy of WordPress being tested.
// wordpress/wp-config.php will be ignored.

// WARNING WARNING WARNING!
// These tests will DROP ALL TABLES in the database with the prefix named below.
// DO NOT use a production database or one that is shared with something else.

$current_db = '5.6.17';

if ( $current_db ) {
	define( 'DB_USER', 'msandbox' );
	define( 'DB_PASSWORD', 'msandbox' );

	exec( '~/sandboxes/msb_' . str_replace( '.', '_', $current_db ) . '/start' );
	if ( false === strpos( $GLOBALS['argv'][0], 'install.php' ) ) {
		register_shutdown_function( 'exec', '~/sandboxes/msb_' . str_replace( '.', '_', $current_db ) . '/stop' );
	}
} else {
	define( 'DB_USER', 'wp' );
	define( 'DB_PASSWORD', 'wp' );
}

switch( $current_db ) {
	case '5.0.88':
		define( 'DB_HOST', '127.0.0.1:5088' );
		break;

	case '5.0.96':
		define( 'DB_HOST', '127.0.0.1:5096' );
		break;

	case '5.6.17':
		define( 'DB_HOST', '127.0.0.1:5617' );
		break;

	default:
		define( 'DB_HOST', 'localhost' );
		break;
}

define( 'DB_NAME', 'wordpress_unit_tests' );
define( 'DB_CHARSET', 'utf8' );
define( 'DB_COLLATE', '' );

$table_prefix  = 'wptests_';   // Only numbers, letters, and underscores please!

define( 'WP_TESTS_DOMAIN', 'example.org' );
define( 'WP_TESTS_EMAIL', 'admin@example.org' );
define( 'WP_TESTS_TITLE', 'Test Blog' );

define( 'WP_PHP_BINARY', 'php' );

define( 'WPLANG', '' );