An attempt to try and test CodeIgnitor library

bootstrap.php

<?php

require(__DIR__ . '/../vendor/autoload.php');
// this is a copy of the default index.php shipped with CodeIgnitor
// The system and application_folder variables are replaced
// Also, in this version we do not bootstrap the framework and rather include our own version below
require('loader.php');
// this is a modified version of system/core/CodeIgniter.php
// they do bootstrapping, routing, and dispatching in one place
// so we can't use the whole file because dispatching fails when running tests
require('framework.php');

// set up the test environment database connection
putenv('DATABASE_HOST=localhost');
putenv('DATABASE_USER=user');
putenv('DATABASE_PASSWORD=password');
putenv('DATABASE=database');

// CI uses a singleton approach and creates an instance of a child of this class during dispatch
// We need to make sure that the singleton holder is populated
$controller = new CI_Controller();

framework.php

<?php
/**
 * This file is modified from system/core/CodeIgniter.php
 * I have removed the routing and dispatch logic.
 *
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2016, British Columbia Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package	CodeIgniter
 * @author	EllisLab Dev Team
 * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
 * @copyright	Copyright (c) 2014 - 2016, British Columbia Institute of Technology (http://bcit.ca/)
 * @license	http://opensource.org/licenses/MIT	MIT License
 * @link	https://codeigniter.com
 * @since	Version 1.0.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * System Initialization File
 *
 * Loads the base classes and executes the request.
 *
 * @package		CodeIgniter
 * @subpackage	CodeIgniter
 * @category	Front-controller
 * @author		EllisLab Dev Team
 * @link		https://codeigniter.com/user_guide/
 */

/**
 * CodeIgniter Version
 *
 * @var	string
 *
 */
const CI_VERSION = '3.1.2';

/*
 * ------------------------------------------------------
 *  Load the framework constants
 * ------------------------------------------------------
 */
if (file_exists(APPPATH.'config/'.ENVIRONMENT.'/constants.php'))
{
    require_once(APPPATH.'config/'.ENVIRONMENT.'/constants.php');
}

require_once(APPPATH.'config/constants.php');

/*
 * ------------------------------------------------------
 *  Load the global functions
 * ------------------------------------------------------
 */
require_once(BASEPATH.'core/Common.php');

/*
 * ------------------------------------------------------
 *  Define a custom error handler so we can log PHP errors
 * ------------------------------------------------------
 */
set_error_handler('_error_handler');
set_exception_handler('_exception_handler');
register_shutdown_function('_shutdown_handler');

/*
 * ------------------------------------------------------
 *  Set the subclass_prefix
 * ------------------------------------------------------
 *
 * Normally the "subclass_prefix" is set in the config file.
 * The subclass prefix allows CI to know if a core class is
 * being extended via a library in the local application
 * "libraries" folder. Since CI allows config items to be
 * overridden via data set in the main index.php file,
 * before proceeding we need to know if a subclass_prefix
 * override exists. If so, we will set this value now,
 * before any classes are loaded
 * Note: Since the config file data is cached it doesn't
 * hurt to load it here.
 */
if ( ! empty($assign_to_config['subclass_prefix']))
{
    get_config(array('subclass_prefix' => $assign_to_config['subclass_prefix']));
}

/*
 * ------------------------------------------------------
 *  Should we use a Composer autoloader?
 * ------------------------------------------------------
 */
if ($composer_autoload = config_item('composer_autoload'))
{
    if ($composer_autoload === TRUE)
    {
        file_exists(APPPATH.'vendor/autoload.php')
            ? require_once(APPPATH.'vendor/autoload.php')
            : log_message('error', '$config[\'composer_autoload\'] is set to TRUE but '.APPPATH.'vendor/autoload.php was not found.');
    }
    elseif (file_exists($composer_autoload))
    {
        require_once($composer_autoload);
    }
    else
    {
        log_message('error', 'Could not find the specified $config[\'composer_autoload\'] path: '.$composer_autoload);
    }
}

/*
 * ------------------------------------------------------
 *  Start the timer... tick tock tick tock...
 * ------------------------------------------------------
 */
$BM =& load_class('Benchmark', 'core');
$BM->mark('total_execution_time_start');
$BM->mark('loading_time:_base_classes_start');

/*
 * ------------------------------------------------------
 *  Instantiate the hooks class
 * ------------------------------------------------------
 */
$EXT =& load_class('Hooks', 'core');

/*
 * ------------------------------------------------------
 *  Is there a "pre_system" hook?
 * ------------------------------------------------------
 */
$EXT->call_hook('pre_system');

/*
 * ------------------------------------------------------
 *  Instantiate the config class
 * ------------------------------------------------------
 *
 * Note: It is important that Config is loaded first as
 * most other classes depend on it either directly or by
 * depending on another class that uses it.
 *
 */
$CFG =& load_class('Config', 'core');

// Do we have any manually set config items in the index.php file?
if (isset($assign_to_config) && is_array($assign_to_config))
{
    foreach ($assign_to_config as $key => $value)
    {
        $CFG->set_item($key, $value);
    }
}

/*
 * ------------------------------------------------------
 * Important charset-related stuff
 * ------------------------------------------------------
 *
 * Configure mbstring and/or iconv if they are enabled
 * and set MB_ENABLED and ICONV_ENABLED constants, so
 * that we don't repeatedly do extension_loaded() or
 * function_exists() calls.
 *
 * Note: UTF-8 class depends on this. It used to be done
 * in it's constructor, but it's _not_ class-specific.
 *
 */
$charset = strtoupper(config_item('charset'));
ini_set('default_charset', $charset);

if (extension_loaded('mbstring'))
{
    define('MB_ENABLED', TRUE);
    // mbstring.internal_encoding is deprecated starting with PHP 5.6
    // and it's usage triggers E_DEPRECATED messages.
    @ini_set('mbstring.internal_encoding', $charset);
    // This is required for mb_convert_encoding() to strip invalid characters.
    // That's utilized by CI_Utf8, but it's also done for consistency with iconv.
    mb_substitute_character('none');
}
else
{
    define('MB_ENABLED', FALSE);
}

// There's an ICONV_IMPL constant, but the PHP manual says that using
// iconv's predefined constants is "strongly discouraged".
if (extension_loaded('iconv'))
{
    define('ICONV_ENABLED', TRUE);
    // iconv.internal_encoding is deprecated starting with PHP 5.6
    // and it's usage triggers E_DEPRECATED messages.
    @ini_set('iconv.internal_encoding', $charset);
}
else
{
    define('ICONV_ENABLED', FALSE);
}

if (is_php('5.6'))
{
    ini_set('php.internal_encoding', $charset);
}

/*
 * ------------------------------------------------------
 *  Load compatibility features
 * ------------------------------------------------------
 */

require_once(BASEPATH.'core/compat/mbstring.php');
require_once(BASEPATH.'core/compat/hash.php');
require_once(BASEPATH.'core/compat/password.php');
require_once(BASEPATH.'core/compat/standard.php');

/*
 * ------------------------------------------------------
 *  Instantiate the UTF-8 class
 * ------------------------------------------------------
 */
$UNI =& load_class('Utf8', 'core');

/*
 * ------------------------------------------------------
 *  Instantiate the URI class
 * ------------------------------------------------------
 */
$URI =& load_class('URI', 'core');

/*
 * ------------------------------------------------------
 *  Instantiate the routing class and set the routing
 * ------------------------------------------------------
 */
$RTR =& load_class('Router', 'core', isset($routing) ? $routing : NULL);

/*
 * ------------------------------------------------------
 *  Instantiate the output class
 * ------------------------------------------------------
 */
$OUT =& load_class('Output', 'core');

/*
 * -----------------------------------------------------
 * Load the security class for xss and csrf support
 * -----------------------------------------------------
 */
$SEC =& load_class('Security', 'core');

/*
 * ------------------------------------------------------
 *  Load the Input class and sanitize globals
 * ------------------------------------------------------
 */
$IN	=& load_class('Input', 'core');

/*
 * ------------------------------------------------------
 *  Load the Language class
 * ------------------------------------------------------
 */
$LANG =& load_class('Lang', 'core');

/*
 * ------------------------------------------------------
 *  Load the app controller and local controller
 * ------------------------------------------------------
 *
 */
// Load the base controller class
require_once BASEPATH.'core/Controller.php';

/**
 * Reference to the CI_Controller method.
 *
 * Returns current CI instance object
 *
 * @return CI_Controller
 */
function &get_instance()
{
    return CI_Controller::get_instance();
}


// Set a mark point for benchmarking
$BM->mark('loading_time:_base_classes_end');

loader.php

<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2016, British Columbia Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package	CodeIgniter
 * @author	EllisLab Dev Team
 * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
 * @copyright	Copyright (c) 2014 - 2016, British Columbia Institute of Technology (http://bcit.ca/)
 * @license	http://opensource.org/licenses/MIT	MIT License
 * @link	https://codeigniter.com
 * @since	Version 1.0.0
 * @filesource
 */

/*
 *---------------------------------------------------------------
 * APPLICATION ENVIRONMENT
 *---------------------------------------------------------------
 *
 * You can load different configurations depending on your
 * current environment. Setting the environment also influences
 * things like logging and error reporting.
 *
 * This can be set to anything, but default usage is:
 *
 *     development
 *     testing
 *     production
 *
 * NOTE: If you change these, also change the error_reporting() code below
 */
	define('ENVIRONMENT', isset($_SERVER['CI_ENV']) ? $_SERVER['CI_ENV'] : 'development');

/*
 *---------------------------------------------------------------
 * ERROR REPORTING
 *---------------------------------------------------------------
 *
 * Different environments will require different levels of error reporting.
 * By default development will show errors but testing and live will hide them.
 */
switch (ENVIRONMENT)
{
	case 'development':
		error_reporting(-1);
		ini_set('display_errors', 1);
	break;

	case 'testing':
	case 'production':
		ini_set('display_errors', 0);
		if (version_compare(PHP_VERSION, '5.3', '>='))
		{
			error_reporting(E_ALL & ~E_NOTICE & ~E_DEPRECATED & ~E_STRICT & ~E_USER_NOTICE & ~E_USER_DEPRECATED);
		}
		else
		{
			error_reporting(E_ALL & ~E_NOTICE & ~E_STRICT & ~E_USER_NOTICE);
		}
	break;

	default:
		header('HTTP/1.1 503 Service Unavailable.', TRUE, 503);
		echo 'The application environment is not set correctly.';
		exit(1); // EXIT_ERROR
}

/*
 *---------------------------------------------------------------
 * SYSTEM DIRECTORY NAME
 *---------------------------------------------------------------
 *
 * This variable must contain the name of your "system" directory.
 * Set the path if it is not in the same directory as this file.
 */
	$system_path = '../system';

/*
 *---------------------------------------------------------------
 * APPLICATION DIRECTORY NAME
 *---------------------------------------------------------------
 *
 * If you want this front controller to use a different "application"
 * directory than the default one you can set its name here. The directory
 * can also be renamed or relocated anywhere on your server. If you do,
 * use an absolute (full) server path.
 * For more info please see the user guide:
 *
 * https://codeigniter.com/user_guide/general/managing_apps.html
 *
 * NO TRAILING SLASH!
 */
	$application_folder = '../application';

/*
 *---------------------------------------------------------------
 * VIEW DIRECTORY NAME
 *---------------------------------------------------------------
 *
 * If you want to move the view directory out of the application
 * directory, set the path to it here. The directory can be renamed
 * and relocated anywhere on your server. If blank, it will default
 * to the standard location inside your application directory.
 * If you do move this, use an absolute (full) server path.
 *
 * NO TRAILING SLASH!
 */
	$view_folder = '';


/*
 * --------------------------------------------------------------------
 * DEFAULT CONTROLLER
 * --------------------------------------------------------------------
 *
 * Normally you will set your default controller in the routes.php file.
 * You can, however, force a custom routing by hard-coding a
 * specific controller class/function here. For most applications, you
 * WILL NOT set your routing here, but it's an option for those
 * special instances where you might want to override the standard
 * routing in a specific front controller that shares a common CI installation.
 *
 * IMPORTANT: If you set the routing here, NO OTHER controller will be
 * callable. In essence, this preference limits your application to ONE
 * specific controller. Leave the function name blank if you need
 * to call functions dynamically via the URI.
 *
 * Un-comment the $routing array below to use this feature
 */
	// The directory name, relative to the "controllers" directory.  Leave blank
	// if your controller is not in a sub-directory within the "controllers" one
	// $routing['directory'] = '';

	// The controller class file name.  Example:  mycontroller
	// $routing['controller'] = '';

	// The controller function you wish to be called.
	// $routing['function']	= '';


/*
 * -------------------------------------------------------------------
 *  CUSTOM CONFIG VALUES
 * -------------------------------------------------------------------
 *
 * The $assign_to_config array below will be passed dynamically to the
 * config class when initialized. This allows you to set custom config
 * items or override any default config values found in the config.php file.
 * This can be handy as it permits you to share one application between
 * multiple front controller files, with each file containing different
 * config values.
 *
 * Un-comment the $assign_to_config array below to use this feature
 */
	// $assign_to_config['name_of_config_item'] = 'value of config item';



// --------------------------------------------------------------------
// END OF USER CONFIGURABLE SETTINGS.  DO NOT EDIT BELOW THIS LINE
// --------------------------------------------------------------------

/*
 * ---------------------------------------------------------------
 *  Resolve the system path for increased reliability
 * ---------------------------------------------------------------
 */

	// Set the current directory correctly for CLI requests
	if (defined('STDIN'))
	{
		chdir(dirname(__FILE__));
	}

	if (($_temp = realpath($system_path)) !== FALSE)
	{
		$system_path = $_temp.DIRECTORY_SEPARATOR;
	}
	else
	{
		// Ensure there's a trailing slash
		$system_path = strtr(
			rtrim($system_path, '/\\'),
			'/\\',
			DIRECTORY_SEPARATOR.DIRECTORY_SEPARATOR
		).DIRECTORY_SEPARATOR;
	}

	// Is the system path correct?
	if ( ! is_dir($system_path))
	{
		header('HTTP/1.1 503 Service Unavailable.', TRUE, 503);
		echo 'Your system folder path does not appear to be set correctly. Please open the following file and correct this: '.pathinfo(__FILE__, PATHINFO_BASENAME);
		exit(3); // EXIT_CONFIG
	}

/*
 * -------------------------------------------------------------------
 *  Now that we know the path, set the main path constants
 * -------------------------------------------------------------------
 */
	// The name of THIS file
	define('SELF', pathinfo(__FILE__, PATHINFO_BASENAME));

	// Path to the system directory
	define('BASEPATH', $system_path);

	// Path to the front controller (this file) directory
	define('FCPATH', dirname(__FILE__).DIRECTORY_SEPARATOR);

	// Name of the "system" directory
	define('SYSDIR', basename(BASEPATH));

	// The path to the "application" directory
	if (is_dir($application_folder))
	{
		if (($_temp = realpath($application_folder)) !== FALSE)
		{
			$application_folder = $_temp;
		}
		else
		{
			$application_folder = strtr(
				rtrim($application_folder, '/\\'),
				'/\\',
				DIRECTORY_SEPARATOR.DIRECTORY_SEPARATOR
			);
		}
	}
	elseif (is_dir(BASEPATH.$application_folder.DIRECTORY_SEPARATOR))
	{
		$application_folder = BASEPATH.strtr(
			trim($application_folder, '/\\'),
			'/\\',
			DIRECTORY_SEPARATOR.DIRECTORY_SEPARATOR
		);
	}
	else
	{
		header('HTTP/1.1 503 Service Unavailable.', TRUE, 503);
		echo 'Your application folder path does not appear to be set correctly. Please open the following file and correct this: '.SELF;
		exit(3); // EXIT_CONFIG
	}

	define('APPPATH', $application_folder.DIRECTORY_SEPARATOR);

	// The path to the "views" directory
	if ( ! isset($view_folder[0]) && is_dir(APPPATH.'views'.DIRECTORY_SEPARATOR))
	{
		$view_folder = APPPATH.'views';
	}
	elseif (is_dir($view_folder))
	{
		if (($_temp = realpath($view_folder)) !== FALSE)
		{
			$view_folder = $_temp;
		}
		else
		{
			$view_folder = strtr(
				rtrim($view_folder, '/\\'),
				'/\\',
				DIRECTORY_SEPARATOR.DIRECTORY_SEPARATOR
			);
		}
	}
	elseif (is_dir(APPPATH.$view_folder.DIRECTORY_SEPARATOR))
	{
		$view_folder = APPPATH.strtr(
			trim($view_folder, '/\\'),
			'/\\',
			DIRECTORY_SEPARATOR.DIRECTORY_SEPARATOR
		);
	}
	else
	{
		header('HTTP/1.1 503 Service Unavailable.', TRUE, 503);
		echo 'Your view folder path does not appear to be set correctly. Please open the following file and correct this: '.SELF;
		exit(3); // EXIT_CONFIG
	}

	define('VIEWPATH', $view_folder.DIRECTORY_SEPARATOR);

phpunit.xml.dist

<?xml version="1.0" encoding="UTF-8"?>

<!-- https://phpunit.de/manual/current/en/appendixes.configuration.html -->
<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:noNamespaceSchemaLocation="http://schema.phpunit.de/4.8/phpunit.xsd"
         backupGlobals="false"
         colors="true"
         bootstrap="./tests/bootstrap.php"
>
    <php>
        <ini name="error_reporting" value="-1" />
    </php>

    <testsuites>
        <testsuite name="Project Test Suite">
            <directory>tests</directory>
        </testsuite>
    </testsuites>

    <filter>
        <whitelist processUncoveredFilesFromWhitelist="true">
            <directory suffix=".php">src</directory>
        </whitelist>
    </filter>

</phpunit>

TestBase.php

<?php

namespace Test;

use PHPUnit\Framework\TestCase;
use ReflectionClass;
use ReflectionException;

class TestBase extends TestCase
{
    protected $CI;

    /**
     * TestBase constructor.
     * @param string|null $name
     * @param array $data
     * @param string $dataName
     */
    public function __construct(?string $name = null, array $data = [], $dataName = '')
    {
        parent::__construct($name, $data, $dataName);
        if (!defined('BASEPATH')) {
            define('BASEPATH', __DIR__ . '../');
        }
        $this->CI = &get_instance();
    }

    /**
     * @param $methodName
     * @param $object
     * @return \ReflectionMethod
     */
    protected function getMethod($methodName, $object)
    {
        try {
            $class = new ReflectionClass(get_class($object));
            $method = $class->getMethod($methodName);
            $method->setAccessible(true);
            return $method;
        } catch (ReflectionException $e) {
            die("Reflection exception [{$e->getMessage()}]");
        }
    }
}