Add Conflict Problem (#7)

* Add conflict problem

* Fix typo

Author: Landerstraeten

README.md

@@ -41,6 +41,7 @@ throw new ApiProblemException(
 - [UnauthorizedProblem](#unauthorizedproblem)
 - [ValidationApiProblem](#validationapiproblem)
 - [BadRequestProblem](#badrequestproblem)
+- [ConflictProblem](#conflictproblem)
 
 #### ExceptionApiProblem
 
@@ -206,6 +207,21 @@ new BadRequestProblem('Bad request. Bad!.');
 }
 ````
 
+#### ConflictProblem
+
+```php
+use Phpro\ApiProblem\Http\ConflictProblem;
+new ConflictProblem('Duplicated key for book with ID 20.');
+```
+
+```json
+{
+    "status": 409,
+    "type": "http:\/\/www.w3.org\/Protocols\/rfc2616\/rfc2616-sec10.html",
+    "title": "Conflict",
+    "detail": "Duplicated key for book with ID 20."
+}
+````
 
 ### Creating your own problem
 
@@ -215,7 +231,7 @@ Since the RFC is very loose, we made the interface as easy as possible:
 ```php
 use Phpro\ApiProblem\ApiProblemInterface;
 
-class MyProblem implements ApiProbelmInterface
+class MyProblem implements ApiProblemInterface
 {
     public function toArray(): array
     {

spec/Http/ConflictProblemSpec.php

@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace spec\Phpro\ApiProblem\Http;
+
+use Phpro\ApiProblem\Http\ConflictProblem;
+use Phpro\ApiProblem\Http\HttpApiProblem;
+use PhpSpec\ObjectBehavior;
+
+class ConflictProblemSpec extends ObjectBehavior
+{
+    public function let(): void
+    {
+        $this->beConstructedWith('conflict');
+    }
+
+    public function it_is_initializable(): void
+    {
+        $this->shouldHaveType(ConflictProblem::class);
+    }
+
+    public function it_is_an_http_api_problem(): void
+    {
+        $this->shouldHaveType(HttpApiProblem::class);
+    }
+
+    public function it_can_parse_to_array(): void
+    {
+        $this->toArray()->shouldBe([
+            'status' => 409,
+            'type' => HttpApiProblem::TYPE_HTTP_RFC,
+            'title' => HttpApiProblem::getTitleForStatusCode(409),
+            'detail' => 'conflict',
+        ]);
+    }
+}

src/Http/ConflictProblem.php

@@ -0,0 +1,15 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Phpro\ApiProblem\Http;
+
+class ConflictProblem extends HttpApiProblem
+{
+    public function __construct(string $reason)
+    {
+        parent::__construct(409, [
+            'detail' => $reason,
+        ]);
+    }
+}