added code coverage and the first real test

.gitignore

 /vendor/
+/coverage/
 composer.lock

.gitlab-ci.yml

 image: "iras/php7-phalcon-test"
 
 test:
+  artifacts:
+    path:
+    - coverage/
   script:
     - composer install
-    - vendor/bin/phpunit
+    - composer test-wcc

README.md

 # Dependency Injector
 
 A simple and lightweight dependency injector. You will need nothing more to tests your old legacy code.
+
+Did you ever wondered how complicated it could be to write a dependency injector that works? In fact it is very easy
+and you don't need a tons of classes laying around and learn a dozens of new fancy words. 
+
+It is just a storage of functions and values for a specific key. Store your function to create an instance and it get
+executed the first time you need this instance.
+
+Sounds to easy? What about dependencies? Check the examples. It is nothing more needed than this.
  
 ## What is a dependency
 

composer.json

 {
     "name": "tflori/dependency-injector",
+    "type": "library",
+    "keywords": ["di", "dependency injection", "dependency injector", "dependency", "dependencies"],
+    "description": "Easy and lightweight dependency injector",
+    "licence": "MIT",
+    "authors": [
+        {
+            "name": "Thomas Flori",
+            "email": "thflori@gmail.com",
+            "role": "Developer"
+        }
+    ],
+    "scripts": {
+        "test": "phpunit",
+        "test-wcc": "phpunit --coverage-html coverage"
+    },
     "version": "1.0.0-alpha",
     "require-dev": {
         "phpunit/phpunit": "5.5.*",

src/DependencyInjector.php

 <?php
 
-class DependencyInjector {}
+/**
+ * Class DependencyInjector
+ *
+ * This is a Dependency Injector. It gives the opportunity to define how to get a dependency from outside of the code
+ * that needs the dependency. This is especially helpful for testing proposes when you need to mock a dependency.
+ *
+ * You can never get an instance of this class. For usage you have only two static methods.
+ *
+ * Example usage:
+ * DependencyInjector::set('hello', function() { return 'hello'; });
+ * DependencyInjector::set('world', function() { return 'world'; });
+ * echo DependencyInjector:get('hello') . " " . DependencyInjector:.get('world') . "!\n";
+ */
+class DependencyInjector {
+
+    /**
+     * Get a previously defined dependency identified by $name.
+     *
+     * @param string $name
+     * @throws DependencyInjectorException
+     */
+    public static function get($name) {
+        throw new DependencyInjectorException("Unknown dependency '" . $name . "'");
+    }
+}

src/DependencyInjectorException.php

+<?php
+
+class DependencyInjectorException extends Exception {};

tests/DependencyInjectorTest.php

 <?php
 
 use PHPUnit\Framework\TestCase;
+use DependencyInjector as DI;
 
 class DependencyInjectorTest extends TestCase {
+    /**
+     * Test that the setup works - the class should exist
+     */
     public function testSetUp() {
         $this->assertTrue(class_exists('DependencyInjector'));
     }
+
+    /**
+     * Test that DI::get() throws a exception when the requested depency is unknown.
+     *
+     * @expectedException DependencyInjectorException
+     * @expectedExceptionMessage Unknown dependency 'unknown'
+     */
+    public function testGet_throwsForUnknownDependencies() {
+        DI::get('unknown');
+    }
 }