diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 0000000..ef3eb52
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,21 @@
+root = true
+
+[*]
+indent_style = space
+indent_size = 2
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.php]
+indent_size = 4
+
+[*.json]
+indent_size = 4
+
+[composer.lock]
+indent_size = 4
+
+[phpunit.xml.dist]
+indent_size = 4
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..09c3d74
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+/vendor/
+/composer.lock
+/phpunit/
+/phpunit.xml
diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..eba105a
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,17 @@
+dist: trusty
+language: php
+php:
+  - 5.4
+  - 5.5
+  - 5.6
+  - 7.0
+  - 7.1
+cache:
+  directories:
+    - ./vendor/
+before_script:
+  - travis_retry composer install --no-interaction --no-suggest --prefer-source
+script:
+  - composer run tests
+matrix:
+  fast_finish: true
diff --git a/class-php-ico.php b/class-php-ico.php
index 2e9983e..a2102d7 100644
--- a/class-php-ico.php
+++ b/class-php-ico.php
@@ -7,258 +7,276 @@
 Version 1.0.4
 */
 
-class PHP_ICO {
-	/**
-	 * Images in the BMP format.
-	 *
-	 * @var array
-	 * @access private
-	 */
-	var $_images = array();
-
-	/**
-	 * Flag to tell if the required functions exist.
-	 *
-	 * @var boolean
-	 * @access private
-	 */
-	var $_has_requirements = false;
-
-
-	/**
-	 * Constructor - Create a new ICO generator.
-	 *
-	 * If the constructor is not passed a file, a file will need to be supplied using the {@link PHP_ICO::add_image}
-	 * function in order to generate an ICO file.
-	 *
-	 * @param string $file Optional. Path to the source image file.
-	 * @param array $sizes Optional. An array of sizes (each size is an array with a width and height) that the source image should be rendered at in the generated ICO file. If sizes are not supplied, the size of the source image will be used.
-	 */
-	function __construct( $file = false, $sizes = array() ) {
-		$required_functions = array(
-			'getimagesize',
-			'imagecreatefromstring',
-			'imagecreatetruecolor',
-			'imagecolortransparent',
-			'imagecolorallocatealpha',
-			'imagealphablending',
-			'imagesavealpha',
-			'imagesx',
-			'imagesy',
-			'imagecopyresampled',
-		);
-
-		foreach ( $required_functions as $function ) {
-			if ( ! function_exists( $function ) ) {
-				trigger_error( "The PHP_ICO class was unable to find the $function function, which is part of the GD library. Ensure that the system has the GD library installed and that PHP has access to it through a PHP interface, such as PHP's GD module. Since this function was not found, the library will be unable to create ICO files." );
-				return;
-			}
-		}
-
-		$this->_has_requirements = true;
-
-
-		if ( false != $file )
-			$this->add_image( $file, $sizes );
-	}
-
-	/**
-	 * Add an image to the generator.
-	 *
-	 * This function adds a source image to the generator. It serves two main purposes: add a source image if one was
-	 * not supplied to the constructor and to add additional source images so that different images can be supplied for
-	 * different sized images in the resulting ICO file. For instance, a small source image can be used for the small
-	 * resolutions while a larger source image can be used for large resolutions.
-	 *
-	 * @param string $file Path to the source image file.
-	 * @param array $sizes Optional. An array of sizes (each size is an array with a width and height) that the source image should be rendered at in the generated ICO file. If sizes are not supplied, the size of the source image will be used.
-	 * @return boolean true on success and false on failure.
-	 */
-	function add_image( $file, $sizes = array() ) {
-		if ( ! $this->_has_requirements )
-			return false;
-
-		if ( false === ( $im = $this->_load_image_file( $file ) ) )
-			return false;
-
-
-		if ( empty( $sizes ) )
-			$sizes = array( imagesx( $im ), imagesy( $im ) );
-
-		// If just a single size was passed, put it in array.
-		if ( ! is_array( $sizes[0] ) )
-			$sizes = array( $sizes );
-
-		foreach ( (array) $sizes as $size ) {
-			list( $width, $height ) = $size;
-
-			$new_im = imagecreatetruecolor( $width, $height );
-
-			imagecolortransparent( $new_im, imagecolorallocatealpha( $new_im, 0, 0, 0, 127 ) );
-			imagealphablending( $new_im, false );
-			imagesavealpha( $new_im, true );
-
-			$source_width = imagesx( $im );
-			$source_height = imagesy( $im );
-
-			if ( false === imagecopyresampled( $new_im, $im, 0, 0, 0, 0, $width, $height, $source_width, $source_height ) )
-				continue;
-
-			$this->_add_image_data( $new_im );
-		}
-
-		return true;
-	}
-
-	/**
-	 * Write the ICO file data to a file path.
-	 *
-	 * @param string $file Path to save the ICO file data into.
-	 * @return boolean true on success and false on failure.
-	 */
-	function save_ico( $file ) {
-		if ( ! $this->_has_requirements )
-			return false;
+class PHP_ICO
+{
+    /**
+     * Images in the BMP format.
+     *
+     * @var array
+     */
+    private $_images = array();
+
+    /**
+     * Flag to tell if the required functions exist.
+     *
+     * @var boolean
+     */
+    private $_has_requirements = false;
+
+
+    /**
+     * Constructor - Create a new ICO generator.
+     *
+     * If the constructor is not passed a file, a file will need to be supplied using the {@link PHP_ICO::add_image}
+     * function in order to generate an ICO file.
+     *
+     * @param string $file Optional. Path to the source image file.
+     * @param array $sizes Optional. An array of sizes (each size is an array with a width and height) that the source image should be rendered at in the generated ICO file. If sizes are not supplied, the size of the source image will be used.
+     */
+    public function __construct($file = false, $sizes = array())
+    {
+        $required_functions = array(
+            'getimagesize',
+            'imagecreatefromstring',
+            'imagecreatetruecolor',
+            'imagecolortransparent',
+            'imagecolorallocatealpha',
+            'imagealphablending',
+            'imagesavealpha',
+            'imagesx',
+            'imagesy',
+            'imagecopyresampled',
+        );
+
+        foreach ($required_functions as $function) {
+            if (! function_exists($function)) {
+                trigger_error("The PHP_ICO class was unable to find the $function function, which is part of the GD library. Ensure that the system has the GD library installed and that PHP has access to it through a PHP interface, such as PHP's GD module. Since this function was not found, the library will be unable to create ICO files.");
+                return;
+            }
+        }
+
+        $this->_has_requirements = true;
+
+
+        if (false != $file) {
+            $this->add_image($file, $sizes);
+        }
+    }
+
+    /**
+     * Add an image to the generator.
+     *
+     * This function adds a source image to the generator. It serves two main purposes: add a source image if one was
+     * not supplied to the constructor and to add additional source images so that different images can be supplied for
+     * different sized images in the resulting ICO file. For instance, a small source image can be used for the small
+     * resolutions while a larger source image can be used for large resolutions.
+     *
+     * @param string $file Path to the source image file.
+     * @param array $sizes Optional. An array of sizes (each size is an array with a width and height) that the source image should be rendered at in the generated ICO file. If sizes are not supplied, the size of the source image will be used.
+     * @return boolean true on success and false on failure.
+     */
+    public function add_image($file, $sizes = array())
+    {
+        if (! $this->_has_requirements) {
+            return false;
+        }
+
+        if (false === ($im = $this->_load_image_file($file))) {
+            return false;
+        }
+
+
+        if (empty($sizes)) {
+            $sizes = array( imagesx($im), imagesy($im) );
+        }
+
+        // If just a single size was passed, put it in array.
+        if (! is_array($sizes[0])) {
+            $sizes = array( $sizes );
+        }
+
+        foreach ((array) $sizes as $size) {
+            list($width, $height) = $size;
+
+            $new_im = imagecreatetruecolor($width, $height);
+
+            imagecolortransparent($new_im, imagecolorallocatealpha($new_im, 0, 0, 0, 127));
+            imagealphablending($new_im, false);
+            imagesavealpha($new_im, true);
+
+            $source_width = imagesx($im);
+            $source_height = imagesy($im);
+
+            if (false === imagecopyresampled($new_im, $im, 0, 0, 0, 0, $width, $height, $source_width, $source_height)) {
+                continue;
+            }
+
+            $this->_add_image_data($new_im);
+        }
+
+        return true;
+    }
+
+    /**
+     * Write the ICO file data to a file path.
+     *
+     * @param string $file Path to save the ICO file data into.
+     * @return boolean true on success and false on failure.
+     */
+    public function save_ico($file)
+    {
+        if (! $this->_has_requirements) {
+            return false;
+        }
+
+        if (false === ($data = $this->_get_ico_data())) {
+            return false;
+        }
 
-		if ( false === ( $data = $this->_get_ico_data() ) )
-			return false;
+        if (false === ($fh = fopen($file, 'w'))) {
+            return false;
+        }
 
-		if ( false === ( $fh = fopen( $file, 'w' ) ) )
-			return false;
+        if (false === (fwrite($fh, $data))) {
+            fclose($fh);
+            return false;
+        }
 
-		if ( false === ( fwrite( $fh, $data ) ) ) {
-			fclose( $fh );
-			return false;
-		}
+        fclose($fh);
 
-		fclose( $fh );
+        return true;
+    }
 
-		return true;
-	}
+    /**
+     * Generate the final ICO data by creating a file header and adding the image data.
+     */
+    private function _get_ico_data()
+    {
+        if (! is_array($this->_images) || empty($this->_images)) {
+            return false;
+        }
 
-	/**
-	 * Generate the final ICO data by creating a file header and adding the image data.
-	 *
-	 * @access private
-	 */
-	function _get_ico_data() {
-		if ( ! is_array( $this->_images ) || empty( $this->_images ) )
-			return false;
 
+        $data = pack('vvv', 0, 1, count($this->_images));
+        $pixel_data = '';
 
-		$data = pack( 'vvv', 0, 1, count( $this->_images ) );
-		$pixel_data = '';
+        $icon_dir_entry_size = 16;
 
-		$icon_dir_entry_size = 16;
+        $offset = 6 + ($icon_dir_entry_size * count($this->_images));
 
-		$offset = 6 + ( $icon_dir_entry_size * count( $this->_images ) );
+        foreach ($this->_images as $image) {
+            $data .= pack('CCCCvvVV', $image['width'], $image['height'], $image['color_palette_colors'], 0, 1, $image['bits_per_pixel'], $image['size'], $offset);
+            $pixel_data .= $image['data'];
 
-		foreach ( $this->_images as $image ) {
-			$data .= pack( 'CCCCvvVV', $image['width'], $image['height'], $image['color_palette_colors'], 0, 1, $image['bits_per_pixel'], $image['size'], $offset );
-			$pixel_data .= $image['data'];
+            $offset += $image['size'];
+        }
 
-			$offset += $image['size'];
-		}
+        $data .= $pixel_data;
+        unset($pixel_data);
 
-		$data .= $pixel_data;
-		unset( $pixel_data );
 
+        return $data;
+    }
 
-		return $data;
-	}
+    /**
+     * Take a GD image resource and change it into a raw BMP format.
+     */
+    private function _add_image_data($im)
+    {
+        $width = imagesx($im);
+        $height = imagesy($im);
 
-	/**
-	 * Take a GD image resource and change it into a raw BMP format.
-	 *
-	 * @access private
-	 */
-	function _add_image_data( $im ) {
-		$width = imagesx( $im );
-		$height = imagesy( $im );
 
+        $pixel_data = array();
 
-		$pixel_data = array();
+        $opacity_data = array();
+        $current_opacity_val = 0;
 
-		$opacity_data = array();
-		$current_opacity_val = 0;
+        for ($y = $height - 1; $y >= 0; $y--) {
+            for ($x = 0; $x < $width; $x++) {
+                $color = imagecolorat($im, $x, $y);
 
-		for ( $y = $height - 1; $y >= 0; $y-- ) {
-			for ( $x = 0; $x < $width; $x++ ) {
-				$color = imagecolorat( $im, $x, $y );
+                $alpha = ($color & 0x7F000000) >> 24;
+                $alpha = (1 - ($alpha / 127)) * 255;
 
-				$alpha = ( $color & 0x7F000000 ) >> 24;
-				$alpha = ( 1 - ( $alpha / 127 ) ) * 255;
+                $color &= 0xFFFFFF;
+                $color |= 0xFF000000 & ($alpha << 24);
 
-				$color &= 0xFFFFFF;
-				$color |= 0xFF000000 & ( $alpha << 24 );
+                $pixel_data[] = $color;
 
-				$pixel_data[] = $color;
 
+                $opacity = ($alpha <= 127) ? 1 : 0;
 
-				$opacity = ( $alpha <= 127 ) ? 1 : 0;
+                $current_opacity_val = ($current_opacity_val << 1) | $opacity;
 
-				$current_opacity_val = ( $current_opacity_val << 1 ) | $opacity;
+                if ((($x + 1) % 32) == 0) {
+                    $opacity_data[] = $current_opacity_val;
+                    $current_opacity_val = 0;
+                }
+            }
 
-				if ( ( ( $x + 1 ) % 32 ) == 0 ) {
-					$opacity_data[] = $current_opacity_val;
-					$current_opacity_val = 0;
-				}
-			}
+            if (($x % 32) > 0) {
+                while (($x++ % 32) > 0) {
+                    $current_opacity_val = $current_opacity_val << 1;
+                }
 
-			if ( ( $x % 32 ) > 0 ) {
-				while ( ( $x++ % 32 ) > 0 )
-					$current_opacity_val = $current_opacity_val << 1;
+                $opacity_data[] = $current_opacity_val;
+                $current_opacity_val = 0;
+            }
+        }
 
-				$opacity_data[] = $current_opacity_val;
-				$current_opacity_val = 0;
-			}
-		}
+        $image_header_size = 40;
+        $color_mask_size = $width * $height * 4;
+        $opacity_mask_size = (ceil($width / 32) * 4) * $height;
 
-		$image_header_size = 40;
-		$color_mask_size = $width * $height * 4;
-		$opacity_mask_size = ( ceil( $width / 32 ) * 4 ) * $height;
 
+        $data = pack('VVVvvVVVVVV', 40, $width, ($height * 2), 1, 32, 0, 0, 0, 0, 0, 0);
 
-		$data = pack( 'VVVvvVVVVVV', 40, $width, ( $height * 2 ), 1, 32, 0, 0, 0, 0, 0, 0 );
+        foreach ($pixel_data as $color) {
+            $data .= pack('V', $color);
+        }
 
-		foreach ( $pixel_data as $color )
-			$data .= pack( 'V', $color );
+        foreach ($opacity_data as $opacity) {
+            $data .= pack('N', $opacity);
+        }
 
-		foreach ( $opacity_data as $opacity )
-			$data .= pack( 'N', $opacity );
 
+        $image = array(
+            'width'                => $width,
+            'height'               => $height,
+            'color_palette_colors' => 0,
+            'bits_per_pixel'       => 32,
+            'size'                 => $image_header_size + $color_mask_size + $opacity_mask_size,
+            'data'                 => $data,
+        );
 
-		$image = array(
-			'width'                => $width,
-			'height'               => $height,
-			'color_palette_colors' => 0,
-			'bits_per_pixel'       => 32,
-			'size'                 => $image_header_size + $color_mask_size + $opacity_mask_size,
-			'data'                 => $data,
-		);
+        $this->_images[] = $image;
+    }
 
-		$this->_images[] = $image;
-	}
+    /**
+     * Read in the source image file and convert it into a GD image resource.
+     */
+    private function _load_image_file($file)
+    {
+        if (!is_string($file) || empty($file)) {
+            return false;
+        }
+        // Run a cheap check to verify that it is an image file.
+        if (false === ($size = getimagesize($file))) {
+            return false;
+        }
 
-	/**
-	 * Read in the source image file and convert it into a GD image resource.
-	 *
-	 * @access private
-	 */
-	function _load_image_file( $file ) {
-		// Run a cheap check to verify that it is an image file.
-		if ( false === ( $size = getimagesize( $file ) ) )
-			return false;
+        if (false === ($file_data = file_get_contents($file))) {
+            return false;
+        }
 
-		if ( false === ( $file_data = file_get_contents( $file ) ) )
-			return false;
+        if (false === ($im = imagecreatefromstring($file_data))) {
+            return false;
+        }
 
-		if ( false === ( $im = imagecreatefromstring( $file_data ) ) )
-			return false;
+        unset($file_data);
 
-		unset( $file_data );
 
-
-		return $im;
-	}
+        return $im;
+    }
 }
diff --git a/composer.json b/composer.json
index 71d4a93..14aa203 100644
--- a/composer.json
+++ b/composer.json
@@ -12,6 +12,10 @@
             "role": "Developer"
         }
     ],
+    "config": {
+        "optimize-autoloader": true,
+        "sort-packages": true
+    },
     "support": {
         "issues": "https://github.com/chrisbliss18/php-ico/issues",
         "source": "https://github.com/chrisbliss18/php-ico"
@@ -24,5 +28,20 @@
         "classmap": [
             "class-php-ico.php"
         ]
+    },
+    "autoload-dev": {
+        "psr-4": {
+            "PHP_ICO\\Tests\\": "tests/"
+        }
+    },
+    "require-dev": {
+        "friendsofphp/php-cs-fixer": "^1.12",
+        "phpunit/phpunit": "^4.8||^5.6"
+    },
+    "scripts": {
+        "tests" : [
+            "php-cs-fixer fix --verbose --level=psr2 class-php-ico.php --dry-run",
+            "phpunit"
+        ]
     }
 }
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
new file mode 100644
index 0000000..f456179
--- /dev/null
+++ b/phpunit.xml.dist
@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit
+    backupGlobals="true"
+    backupStaticAttributes="false"
+    bootstrap="vendor/autoload.php"
+    colors="true"
+    convertErrorsToExceptions="true"
+    convertNoticesToExceptions="true"
+    convertWarningsToExceptions="true"
+    failOnRisky="true"
+    failOnWarning="true"
+    processIsolation="false"
+    stopOnError="false"
+    stopOnFailure="false"
+    syntaxCheck="true"
+>
+    <testsuites>
+        <testsuite name="PHP_ICO Test Suite">
+            <directory suffix="Test.php">./tests</directory>
+        </testsuite>
+    </testsuites>
+    <filter>
+        <whitelist processUncoveredFilesFromWhitelist="true">
+            <file>./class-php-ico.php</file>
+        </whitelist>
+    </filter>
+    <logging>
+        <log
+            type="coverage-text"
+            target="php://stdout"
+            showUncoveredFiles="true"
+            showOnlySummary="false"
+        />
+    </logging>
+</phpunit>
diff --git a/tests/OutputIcoTest.php b/tests/OutputIcoTest.php
new file mode 100644
index 0000000..3f57299
--- /dev/null
+++ b/tests/OutputIcoTest.php
@@ -0,0 +1,141 @@
+<?php
+declare (strict_types=1);
+
+namespace PHP_ICO\Tests;
+
+use PHP_ICO;
+use PHPUnit_Framework_TestCase;
+
+/**
+ * Class EasyDBTest
+ * @package ParagonIE\EasyDB\Tests
+ */
+class OutputIcoTest extends PHPUnit_Framework_TestCase
+{
+
+    public function goodAddImageSingleProvider()
+    {
+        return array(
+            array(
+                __DIR__ . DIRECTORY_SEPARATOR . 'test-ico-1.gif',
+                array(),
+            ),
+            array(
+                __DIR__ . DIRECTORY_SEPARATOR . 'test-ico-1.jpg',
+                array(),
+            ),
+            array(
+                __DIR__ . DIRECTORY_SEPARATOR . 'test-ico-1.png',
+                array(),
+            ),
+            array(
+                __DIR__ . DIRECTORY_SEPARATOR . 'test-ico-1.gif',
+                array(16,16),
+            ),
+            array(
+                __DIR__ . DIRECTORY_SEPARATOR . 'test-ico-1.jpg',
+                array(16, 16),
+            ),
+            array(
+                __DIR__ . DIRECTORY_SEPARATOR . 'test-ico-1.png',
+                array(16, 16),
+            ),
+            array(
+                __DIR__ . DIRECTORY_SEPARATOR . 'test-ico-1.gif',
+                array(
+                    array(16,16),
+                ),
+            ),
+            array(
+                __DIR__ . DIRECTORY_SEPARATOR . 'test-ico-1.jpg',
+                array(
+                    array(16,16),
+                ),
+            ),
+            array(
+                __DIR__ . DIRECTORY_SEPARATOR . 'test-ico-1.png',
+                array(
+                    array(16,16),
+                ),
+            ),
+        );
+    }
+
+    public function badAddImageSingleProvider_invalidFile()
+    {
+        return array(
+            array(
+                null,
+                array(),
+            ),
+            array(
+                false,
+                array(),
+            ),
+            array(
+                true,
+                array(),
+            ),
+            array(
+                1,
+                array(),
+            ),
+            array(
+                '',
+                array(),
+            ),
+            array(
+                __DIR__ . DIRECTORY_SEPARATOR . 'test-ico-1.xcf',
+                array(),
+            ),
+        );
+    }
+
+    public function badSaveIcoProvider_GetIcoDataReturnsFalse()
+    {
+        return array(
+            array(
+                array(),
+            ),
+        );
+    }
+
+    /**
+    * @dataProvider goodAddImageSingleProvider
+    */
+    public function testConstructorOnly($file, $sizes) {
+        $this->assertTrue(is_file($file));
+        $this->assertTrue(is_readable($file));
+        $this->assertTrue(is_file($file . '.ico'));
+        $this->assertTrue(is_readable($file . '.ico'));
+
+        $ico = new PHP_ICO($file, $sizes);
+        $outputToHere = tempnam(sys_get_temp_dir(), 'PHP_ICO_tests');
+        $this->assertTrue($ico->save_ico($outputToHere));
+        $this->assertSame(sha1_file($file . '.ico'), sha1_file($outputToHere));
+        unlink($outputToHere);
+    }
+
+    /**
+    * @dataProvider badAddImageSingleProvider_invalidFile
+    */
+    public function testAddImageBadFiles($file, $sizes) {
+        $ico = new PHP_ICO();
+        $this->assertFalse($ico->add_image($file, $sizes));
+    }
+
+    /**
+    * @dataProvider badSaveIcoProvider_GetIcoDataReturnsFalse
+    */
+    public function testSaveIcoBadData($arrayOfFilesAndSizes)
+    {
+        $ico = new PHP_ICO();
+        foreach ($arrayOfFilesAndSizes as $file => $sizes)
+        {
+            $ico->add_image($file, $sizes);
+        }
+        $outputToHere = tempnam(sys_get_temp_dir(), 'PHP_ICO_tests');
+        $this->assertFalse($ico->save_ico($outputToHere));
+        unlink($outputToHere);
+    }
+}
diff --git a/tests/test-ico-1.gif b/tests/test-ico-1.gif
new file mode 100644
index 0000000..9c0a951
Binary files /dev/null and b/tests/test-ico-1.gif differ
diff --git a/tests/test-ico-1.gif.ico b/tests/test-ico-1.gif.ico
new file mode 100644
index 0000000..5b3d22a
Binary files /dev/null and b/tests/test-ico-1.gif.ico differ
diff --git a/tests/test-ico-1.jpg b/tests/test-ico-1.jpg
new file mode 100644
index 0000000..e21c5cc
Binary files /dev/null and b/tests/test-ico-1.jpg differ
diff --git a/tests/test-ico-1.jpg.ico b/tests/test-ico-1.jpg.ico
new file mode 100644
index 0000000..d2e2e83
Binary files /dev/null and b/tests/test-ico-1.jpg.ico differ
diff --git a/tests/test-ico-1.png b/tests/test-ico-1.png
new file mode 100644
index 0000000..f110ae2
Binary files /dev/null and b/tests/test-ico-1.png differ
diff --git a/tests/test-ico-1.png.ico b/tests/test-ico-1.png.ico
new file mode 100644
index 0000000..5b3d22a
Binary files /dev/null and b/tests/test-ico-1.png.ico differ
diff --git a/tests/test-ico-1.xcf b/tests/test-ico-1.xcf
new file mode 100644
index 0000000..54104cb
Binary files /dev/null and b/tests/test-ico-1.xcf differ