Add two more tests for optional and nullable arguments fallbacks

Author: e1himself

specs/Fixtures/MyNullableArgumentService.php

@@ -0,0 +1,15 @@
+<?php
+
+namespace Technically\DependencyResolver\Specs\Fixtures;
+
+use Psr\Container\ContainerInterface;
+
+final class MyNullableArgumentService
+{
+    public $container;
+
+    public function __construct(?ContainerInterface $container)
+    {
+        $this->container = $container;
+    }
+}

specs/Fixtures/MyOptionalArgumentService.php

@@ -0,0 +1,13 @@
+<?php
+
+namespace Technically\DependencyResolver\Specs\Fixtures;
+
+final class MyOptionalArgumentService
+{
+    public $name;
+
+    public function __construct(string $name = 'MyOptionalArgumentService')
+    {
+        $this->name = $name;
+    }
+}

specs/dependency-resolver.spec.php

@@ -7,6 +7,8 @@
 use Technically\DependencyResolver\Specs\Fixtures\MyAbstractClass;
 use Technically\DependencyResolver\Specs\Fixtures\MyConcreteContainerService;
 use Technically\DependencyResolver\Specs\Fixtures\MyAbstractContainerService;
+use Technically\DependencyResolver\Specs\Fixtures\MyNullableArgumentService;
+use Technically\DependencyResolver\Specs\Fixtures\MyOptionalArgumentService;
 
 describe('DependencyResolver', function() {
     it('should instantiate', function () {
@@ -49,6 +51,26 @@
         assert($resolved->container !== $container);
     });
 
+    it('should instantiate a class falling back to default values, if possible', function () {
+        $container = new ArrayContainer();
+        $resolver = new DependencyResolver($container);
+
+        $resolved = $resolver->resolve(MyOptionalArgumentService::class);
+
+        assert($resolved instanceof MyOptionalArgumentService);
+        assert($resolved->name === 'MyOptionalArgumentService');
+    });
+
+    it('should instantiate a class falling back to null when there is no other choice', function () {
+        $container = new ArrayContainer();
+        $resolver = new DependencyResolver($container);
+
+        $resolved = $resolver->resolve(MyNullableArgumentService::class);
+
+        assert($resolved instanceof MyNullableArgumentService);
+        assert($resolved->container === null);
+    });
+
     it('should throw exception if class being resolved is abstract', function () {
         $container = new ArrayContainer();
         $resolver = new DependencyResolver($container);