diff --git a/.editorconfig b/.editorconfig
deleted file mode 100644
index 1513441..0000000
--- a/.editorconfig
+++ /dev/null
@@ -1,13 +0,0 @@
-root = true
-
-[*]
-end_of_line = lf
-insert_final_newline = true
-
-[*.json]
-indent_style = space
-indent_size = 2
-
-[*.{php,xml}]
-indent_style = space
-indent_size = 4
diff --git a/.gitignore b/.gitignore
index fd2bdae..3a9875b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,2 @@
-*.xml
+/vendor/
 composer.lock
-vendor/
diff --git a/README.md b/README.md
deleted file mode 100644
index 3e01ab8..0000000
--- a/README.md
+++ /dev/null
@@ -1,38 +0,0 @@
-# gmail-filter-builder
-
-## Description
-
-Inspired by the [gmail-britta](https://github.com/antifuchs/gmail-britta) Ruby library, the Gmail Filter Builder generates XML that can be imported into Gmail’s filter settings.
-
-## Usage
-
-* Run `composer require opdavies/gmail-filter-builder` to download the library.
-* Create a new PHP file and require `autoload.php`.
-* Create an array of `GmailFilter` objects, each with it’s required methods.
-* Pass the filters into an instance of `GmailFilterBuilder`.
-
-```php
-require __DIR__ . '/vendor/autoload.php';
-
-$filters = [];
-
-// Add filters.
-$filters[] = GmailFilter::create(
-    ...
-);
-
-// Display the output.
-new GmailFilterBuilder($filters);
-```
-
-To generate the output, run PHP on the file - e.g. `php generate.php`.
-
-By default, the output is displayed on screen. To generate a file, use the greater than symbol followed by a file name - e.g. `php generate.php > filters.xml`.
-
-## Example
-
-For a working example, see the [opdavies/gmail-filters](https://github.com/opdavies/gmail-filters/blob/master/generate.php) repository.
-
-## License
-
-MIT
diff --git a/composer.json b/composer.json
index 309e791..e182008 100644
--- a/composer.json
+++ b/composer.json
@@ -1,30 +1,21 @@
 {
-  "name": "opdavies/gmail-filter-builder",
-  "description": "",
-  "authors": [
-    {
-      "name": "Oliver Davies",
-      "email": "oliver@oliverdavies.uk"
+    "name": "opdavies/gmail-filter-builder",
+    "description": "Generates XML to import as Gmail filters.",
+    "type": "library",
+    "license": "MIT",
+    "authors": [
+        {
+            "name": "Oliver Davies",
+            "email": "oliver@oliverdavies.uk"
+        }
+    ],
+    "require": {},
+    "require-dev": {
+        "phpunit/phpunit": "^5.7"
+    },
+    "autoload": {
+        "psr-4": {
+            "Opdavies\\GmailFilterBuilder\\": "src/"
+        }
     }
-  ],
-  "license": "MIT",
-  "autoload": {
-    "psr-4": {
-      "Opdavies\\GmailFilterBuilder\\": "src/Opdavies/GmailFilterBuilder"
-    }
-  },
-  "require": {
-    "opdavies/twig-extensions": "^1.1"
-  },
-  "extra": {
-    "branch-alias": {
-      "dev-master": "0.4-dev"
-    }
-  },
-  "require-dev": {
-    "phpunit/phpunit": "^5.6"
-  },
-  "config": {
-    "sort-packages": true
-  }
 }
diff --git a/phpunit.xml b/phpunit.xml
deleted file mode 100644
index 580ee27..0000000
--- a/phpunit.xml
+++ /dev/null
@@ -1,21 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/5.6/phpunit.xsd"
-         bootstrap="vendor/autoload.php"
-         backupGlobals="false"
-         beStrictAboutCoversAnnotation="true"
-         beStrictAboutOutputDuringTests="true"
-         beStrictAboutTestsThatDoNotTestAnything="true"
-         beStrictAboutTodoAnnotatedTests="true"
-         verbose="true"
-         colors="true">
-    <testsuite>
-        <directory suffix="Test.php">tests</directory>
-    </testsuite>
-
-    <filter>
-        <whitelist processUncoveredFilesFromWhitelist="true">
-            <directory suffix=".php">src</directory>
-        </whitelist>
-    </filter>
-</phpunit>
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
new file mode 100644
index 0000000..a6907ba
--- /dev/null
+++ b/phpunit.xml.dist
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit bootstrap="./vendor/autoload.php"
+         colors="true"
+         convertErrorsToExceptions="true"
+         convertNoticesToExceptions="true"
+         convertWarningsToExceptions="true"
+         stopOnFailure="true">
+    <testsuites>
+        <testsuite name="Unit tests">
+            <directory suffix="Test.php">./tests/Unit</directory>
+        </testsuite>
+    </testsuites>
+</phpunit>
diff --git a/src/Opdavies/GmailFilterBuilder/Builder.php b/src/Opdavies/GmailFilterBuilder/Builder.php
deleted file mode 100644
index 379336c..0000000
--- a/src/Opdavies/GmailFilterBuilder/Builder.php
+++ /dev/null
@@ -1,82 +0,0 @@
-<?php
-
-namespace Opdavies\GmailFilterBuilder;
-
-use Opdavies\Twig\Extensions\TwigBooleanStringExtension;
-use Twig_Environment;
-use Twig_Loader_Filesystem;
-
-class Builder
-{
-    /**
-     * @var string
-     */
-    private $name;
-
-    /**
-     * @var string
-     */
-    private $email;
-
-    /**
-     * @var Twig_Environment
-     */
-    private $twig;
-
-    /**
-     * An array of filters.
-     *
-     * @var GmailFilter[]
-     */
-    private $filters = [];
-
-    public function __construct(array $filters)
-    {
-        $this->twig = new Twig_Environment(
-            new Twig_Loader_Filesystem(__DIR__.'/../../../templates')
-        );
-
-        $this->twig->addExtension(new TwigBooleanStringExtension());
-
-        $this->filters = $filters;
-
-        return $this->generate();
-    }
-
-    public function __toString()
-    {
-        return $this->generate();
-    }
-
-    /**
-     * Build Gmail filters.
-     *
-     * @param GmailFilter[] $filters
-     *   An array of filters to process.
-     *
-     * @return $this
-     */
-    public static function build(array $filters)
-    {
-        return new static($filters);
-    }
-
-    /**
-     * @return string
-     */
-    private function generate()
-    {
-        ob_start();
-
-        print $this->twig->render(
-            'filters.xml.twig',
-            [
-                'name' => $this->name,
-                'email' => $this->email,
-                'filters' => $this->filters,
-            ]
-        );
-
-        return ob_get_contents();
-    }
-}
diff --git a/src/Opdavies/GmailFilterBuilder/Filter.php b/src/Opdavies/GmailFilterBuilder/Filter.php
deleted file mode 100644
index 3125ace..0000000
--- a/src/Opdavies/GmailFilterBuilder/Filter.php
+++ /dev/null
@@ -1,240 +0,0 @@
-<?php
-
-namespace Opdavies\GmailFilterBuilder;
-
-class Filter
-{
-    /**
-     * @param array
-     */
-    private $conditions = [];
-
-    /**
-     * @param array
-     */
-    private $labels = [];
-
-    /**
-     * @var bool
-     */
-    private $archive = false;
-
-    /**
-     * @var bool
-     */
-    private $spam = false;
-
-    /**
-     * @var bool
-     */
-    private $trash = false;
-
-    /**
-     * @var bool
-     */
-    private $neverSpam = false;
-
-    public static function create()
-    {
-        return new static();
-    }
-
-    /**
-     * @return boolean
-     */
-    public function isTrash() {
-        return $this->trash;
-    }
-
-    /**
-     * @return array
-     */
-    public function getConditions() {
-        return $this->conditions;
-    }
-
-    /**
-     * @return array
-     */
-    public function getLabels() {
-        return $this->labels;
-    }
-
-    /**
-     * @return boolean
-     */
-    public function isArchive() {
-        return $this->archive;
-    }
-
-    /**
-     * @return boolean
-     */
-    public function isSpam() {
-        return $this->spam;
-    }
-
-    /**
-     * @return boolean
-     */
-    public function isNeverSpam() {
-        return $this->neverSpam;
-    }
-
-    /**
-     * Condition based on words within the email.
-     *
-     * @param string $value
-     *   The value to compare against.
-     *
-     * @return $this
-     */
-    public function contains($value) {
-        return $this->condition('hasTheWord', $value);
-    }
-
-    /**
-     * Condition based on words within the email.
-     *
-     * @param string $value
-     *   The value to compare against.
-     *
-     * @return $this
-     */
-    public function has($value) {
-        return $this->contains($value);
-    }
-
-    /**
-     * Condition based on the subject.
-     *
-     * @param string $value
-     *   The value to compare against.
-     *
-     * @return $this
-     */
-    public function subject($value) {
-        return $this->condition('subject', $value);
-    }
-
-    /**
-     * Add a label.
-     *
-     * @param string $label
-     *   The label to assign.
-     *
-     * @return $this
-     */
-    public function label($label) {
-        $this->labels[] = $label;
-
-        return $this;
-    }
-
-    /**
-     * Label and archive a message.
-     *
-     * @param string $label
-     *   The label to assign.
-     *
-     * @return $this
-     */
-    public function labelAndArchive($label)
-    {
-        $this->label($label)->archive();
-
-        return $this;
-    }
-
-    /**
-     * @return $this
-     */
-    public function archive() {
-        $this->archive = true;
-
-        return $this;
-    }
-
-    /**
-     * Mark as spam.
-     *
-     * @return $this
-     */
-    public function spam() {
-        $this->spam = true;
-        $this->neverSpam = false;
-
-        return $this;
-    }
-
-    /**
-     * Never mark as spam.
-     *
-     * @return $this
-     */
-    public function neverSpam() {
-        $this->neverSpam = true;
-        $this->spam = false;
-
-        return $this;
-    }
-
-    /**
-     * Who the email is from.
-     *
-     * @param array $values
-     *   An array of names or email addresses for the sender.
-     *
-     * @return $this
-     */
-    public function from(array $values)
-    {
-        $this->condition('from', implode(' OR ', $values));
-
-        return $this;
-    }
-
-    /**
-     * Who the email is sent to.
-     *
-     * @param array $values
-     *   An array of names or email addresses for the receiver.
-     *
-     * @return $this
-     */
-    public function to(array $values)
-    {
-        $this->condition('to', implode(' OR ', $values));
-
-        return $this;
-    }
-
-    /**
-     * Mark a message to be trashed.
-     *
-     * @return $this
-     */
-    public function trash()
-    {
-        $this->trash = TRUE;
-
-        return $this;
-    }
-
-    /**
-     * Add a condition.
-     *
-     * @param string $type
-     *   The type of condition.
-     * @param $value
-     *   The value of the condition.
-     *
-     * @return $this
-     */
-    private function condition($type, $value)
-    {
-        $this->conditions[] = [$type, $value];
-
-        return $this;
-    }
-}
diff --git a/templates/filters.xml.twig b/templates/filters.xml.twig
deleted file mode 100644
index 1314cf7..0000000
--- a/templates/filters.xml.twig
+++ /dev/null
@@ -1,22 +0,0 @@
-<?xml version='1.0' encoding='UTF-8'?><feed xmlns='http://www.w3.org/2005/Atom' xmlns:apps='http://schemas.google.com/apps/2006'>
-    <title>Mail Filters (Blackhole)</title>
-    <id>tag:mail.google.com,2008:filters:1297349082768</id>
-    <updated>2013-02-04T15:50:38Z</updated>
-
-    {% for filter in filters -%}
-        <entry>
-            <category term='filter'></category>
-            <title>Mail Filter</title>
-            <content></content>
-            <apps:property name='shouldArchive' value='{{ filter.isArchive|boolean_string }}'/>
-            <apps:property name='shouldNeverSpam' value='{{ filter.isNeverSpam|boolean_string }}'/>
-            <apps:property name='shouldTrash' value='{{ filter.isTrash|boolean_string }}'/>
-            {% for condition in filter.conditions -%}
-                <apps:property name='{{ condition[0] }}' value='{{ condition[1] }}'/>
-            {%- endfor %}
-            {%- for label in filter.labels %}
-                <apps:property name='label' value='{{ label }}'/>
-            {% endfor %}
-        </entry>
-    {% endfor %}
-</feed>
diff --git a/tests/GmailFilterTest.php b/tests/GmailFilterTest.php
deleted file mode 100644
index 3e071b9..0000000
--- a/tests/GmailFilterTest.php
+++ /dev/null
@@ -1,83 +0,0 @@
-<?php
-
-class GmailFilterTest extends \PHPUnit_Framework_TestCase
-{
-    /**
-     * @var GmailFilter
-     */
-    private $filter;
-
-    /**
-     * {@inheritdoc}
-     */
-    protected function setUp() {
-        parent::setUp();
-
-        $this->filter = new GmailFilter();
-    }
-
-    public function testSingleFrom() {
-        // TODO: Does this need to be done each time?
-        $output = $this->createBuilder([
-            $this->filter->from(['foo@example.com'])
-        ]);
-
-        $this->assertContains('name=\'from\' value=\'foo@example.com\'', $output);
-    }
-
-    public function testMultipleFrom() {
-        $output = $this->createBuilder([
-            $this->filter->from(['foo@example.com', 'bar@example.com'])
-        ]);
-
-        $this->assertContains('name=\'from\' value=\'foo@example.com OR bar@example.com\'', $output);
-    }
-
-    public function testSingleTo() {
-        // TODO: Does this need to be done each time?
-        $output = $this->createBuilder([
-            $this->filter->to(['foo@example.com'])
-        ]);
-
-        $this->assertContains('name=\'to\' value=\'foo@example.com\'', $output);
-    }
-
-    public function testMultipleTo() {
-        $output = $this->createBuilder([
-            $this->filter->to(['foo@example.com', 'bar@example.com'])
-        ]);
-
-        $this->assertContains('name=\'to\' value=\'foo@example.com OR bar@example.com\'', $output);
-    }
-
-    public function testArchive()
-    {
-        $output = $this->createBuilder([
-            $this->filter->archive()
-        ]);
-
-        $this->assertContains('name=\'shouldArchive\' value=\'true\'', $output);
-        $this->assertNotContains('name=\'shouldArchive\' value=\'false\'', $output);
-    }
-
-    public function testLabelAndArchive()
-    {
-        $output = $this->createBuilder([
-            $this->filter->labelAndArchive('foo')
-        ]);
-
-        $this->assertContains('name=\'label\' value=\'foo\'', $output);
-
-        $this->assertContains('name=\'shouldArchive\' value=\'true\'', $output);
-        $this->assertNotContains('name=\'shouldArchive\' value=\'false\'', $output);
-    }
-
-    /**
-     * @param GmailFilter[] $filters An array of filters.
-     *
-     * @return string A string representation of GmailFilterBuilder.
-     */
-    private function createBuilder($filters) {
-        return (string) new GmailFilterBuilder($filters);
-    }
-}