Define value object as final and immutable

spec/ConversationSpec.php

@@ -49,8 +49,7 @@ function it_converse_automatically_and_return_the_last_context($api, $actionMapp
     {
         $api->converse('session_id', 'my text', Argument::any())->willReturn($this->stepData[Step::TYPE_MERGE]);
 
-        $expectedContext = new Context();
-        $expectedContext->add('custom', 'value');
+        $expectedContext = new Context(['custom' => 'value']);
 
         $actionMapping
             ->merge('session_id', Argument::type(Context::class), $this->stepData[Step::TYPE_MERGE]['entities'])
@@ -149,8 +148,7 @@ function it_delegate_action_step_execution($api, $actionMapping)
     {
         $api->converse('session_id', 'my text', Argument::any())->willReturn($this->stepData[Step::TYPE_ACTION]);
 
-        $expectedContext = new Context();
-        $expectedContext->add('custom', 'value');
+        $expectedContext = new Context(['custom' => 'value']);
 
         $actionMapping
             ->action('session_id', $this->stepData[Step::TYPE_ACTION]['action'], Argument::type(Context::class), Argument::type('array'))
@@ -197,8 +195,7 @@ function it_delegate_merge_execution($api, $actionMapping)
     {
         $api->converse('session_id', 'my text', Argument::any())->willReturn($this->stepData[Step::TYPE_MERGE]);
 
-        $expectedContext = new Context();
-        $expectedContext->add('custom', 'value');
+        $expectedContext = new Context(['custom' => 'value']);
 
         $actionMapping
             ->merge('session_id', Argument::type(Context::class), $this->stepData[Step::TYPE_MERGE]['entities'])

spec/EntityApiSpec.php

@@ -41,7 +41,7 @@ function it_should_get_entities($client, ResponseInterface $response)
         $this->get()->shouldReturn($expected);
     }
 
-    function it_should_create_entities($client, ResponseInterface $response, EntityValue $entityValue)
+    function it_should_create_entities($client, ResponseInterface $response)
     {
         $body = '
             {
@@ -54,6 +54,8 @@ function it_should_create_entities($client, ResponseInterface $response, EntityV
             }
         ';
 
+        $entityValue = new EntityValue('value');
+
         $expected = json_decode($body, true);
         $response->getBody()->willReturn($body);
         $client->post('/entities', [
@@ -100,7 +102,7 @@ function it_should_get_an_entity($client, ResponseInterface $response)
         $this->get('first_name')->shouldReturn($expected);
     }
 
-    function it_should_update_an_entity($client, ResponseInterface $response, EntityValue $entityValue)
+    function it_should_update_an_entity($client, ResponseInterface $response)
     {
         $body = '
             {
@@ -113,6 +115,8 @@ function it_should_update_an_entity($client, ResponseInterface $response, Entity
             }
         ';
 
+        $entityValue = new EntityValue('value');
+
         $expected = json_decode($body, true);
         $response->getBody()->willReturn($body);
         $client->put('/entities/favorite_city', [
@@ -139,7 +143,7 @@ function it_should_delete_an_entity($client, ResponseInterface $response)
         $this->delete('favorite_city')->shouldReturn($expected);
     }
 
-    function it_should_add_a_value_to_an_entity($client, ResponseInterface $response, EntityValue $entityValue)
+    function it_should_add_a_value_to_an_entity($client, ResponseInterface $response)
     {
         $body = '
             {
@@ -153,6 +157,8 @@ function it_should_add_a_value_to_an_entity($client, ResponseInterface $response
             }
         ';
 
+        $entityValue = new EntityValue('value');
+
         $expected = json_decode($body, true);
         $response->getBody()->willReturn($body);
         $client->send('POST', '/entities/favorite_city/values', $entityValue)->willReturn($response);

spec/Exception/ConversationExceptionSpec.php

@@ -40,8 +40,10 @@ function it_has_no_context_by_default()
         $this->getContext()->shouldReturn(null);
     }
 
-    function it_can_have_a_context(Context $context)
+    function it_can_have_a_context()
     {
+        $context = new Context();
+
         $this->beConstructedWith('error message', null, $context);
         $this->getContext()->shouldReturn($context);
     }

spec/Model/ContextSpec.php

@@ -4,19 +4,25 @@
 
 use PhpSpec\ObjectBehavior;
 use Prophecy\Argument;
+use Tgallice\Wit\Model\Context;
 use Tgallice\Wit\Model\Entity;
 use Tgallice\Wit\Model\Location;
 
 class ContextSpec extends ObjectBehavior
 {
+    function let()
+    {
+        $this->beConstructedWith(['field' => 'value']);
+    }
+
     function it_is_initializable()
     {
         $this->shouldHaveType('Tgallice\Wit\Model\Context');
     }
 
     function it_has_a_reference_date()
     {
-        $date = new \DateTime();
+        $date = new \DateTimeImmutable();
 
         $this->beConstructedWith([
             'reference_date' => $date,
@@ -34,8 +40,10 @@ function it_has_no_default_location()
         $this->getLocation()->shouldReturn([]);
     }
 
-    function it_can_define_a_location(Location $location)
+    function it_can_define_a_location()
     {
+        $location = new Location(1.1, 1.2);
+
         $this->beConstructedWith([
             'location' => $location,
         ]);
@@ -60,8 +68,10 @@ function it_has_no_default_entities()
         $this->getEntities()->shouldReturn([]);
     }
 
-    function it_can_define_entities(Entity $entity)
+    function it_can_define_entities()
     {
+        $entity = new Entity('id');
+
         $this->beConstructedWith([
             'entities' => [$entity],
         ]);
@@ -81,27 +91,37 @@ function it_can_define_timezone()
         $this->getTimezone()->shouldReturn('timezone');
     }
 
-    function it_can_add_custom_context_field()
+    function it_can_set_custom_context_field()
     {
-        $this->add('context', 'value');
-        $this->get('context')->shouldReturn('value');
+        $context = $this->set('custom', 'value');
+        $context->get('custom')->shouldReturn('value');
     }
 
     function it_can_remove_a_context_field()
     {
-        $this->add('context', 'value');
-        $this->get('context')->shouldReturn('value');
-        $this->remove('context');
-        $this->get('context')->shouldReturn(null);
+        $this->get('field')->shouldReturn('value');
+
+        $context = $this->remove('field');
+        $context->get('field')->shouldReturn(null);
     }
 
     function it_can_check_presence_of_a_context_field()
     {
-        $this->add('context', 'value');
-        $this->has('context')->shouldReturn(true);
+        $this->has('field')->shouldReturn(true);
         $this->has('wrong_context')->shouldReturn(false);
     }
 
+    function it_is_immutable()
+    {
+        $newContext = $this->set('field', 'value');
+        $newContext2 = $newContext->remove('field');
+
+        $this->shouldBeLike($newContext);
+        $this->shouldNotBeEqualTo($newContext);
+        $newContext->get('field')->shouldReturn('value');
+        $newContext2->has('field')->shouldReturn(false);
+    }
+
     function it_must_be_json_serializable()
     {
         $this->shouldHaveType(\JsonSerializable::class);

spec/Model/EntitySpec.php

@@ -29,8 +29,10 @@ function it_has_a_description()
         $this->getDescription()->shouldReturn('description');
     }
 
-    function it_has_values(EntityValue $entityValue)
+    function it_has_values()
     {
+        $entityValue = new EntityValue('value');
+
         $this->beConstructedWith('id', [$entityValue]);
         $this->getValues()->shouldEqual([$entityValue]);
     }

src/Model/Context.php

@@ -2,7 +2,10 @@
 
 namespace Tgallice\Wit\Model;
 
-class Context implements \JsonSerializable
+/**
+ * Context Value Object
+ */
+final class Context implements \JsonSerializable
 {
     /**
      * @var array
@@ -16,10 +19,10 @@ public function __construct($data = [])
     {
         // Ensure the refenre_date field
         if (empty($data['reference_date'])) {
-            $data['reference_date'] = new \DateTime();
+            $data['reference_date'] = new \DateTimeImmutable();
         }
 
-        if ($data['reference_date'] instanceof \DateTime) {
+        if ($data['reference_date'] instanceof \DateTimeInterface) {
             $data['reference_date'] = $data['reference_date']->format(DATE_ISO8601);
         }
 
@@ -71,10 +74,15 @@ public function getTimezone()
     /**
      * @param string $name
      * @param mixed $value
+     *
+     * @return Context
      */
-    public function add($name, $value)
+    public function set($name, $value)
     {
-        $this->data[$name] = $value;
+        $newData = $this->data;
+        $newData[$name] = $value;
+
+        return new self($newData);
     }
 
     /**
@@ -89,10 +97,15 @@ public function get($name)
 
     /**
      * @param string $name
+     *
+     * @return Context
      */
     public function remove($name)
     {
-        unset($this->data[$name]);
+        $newData = $this->data;
+        unset($newData[$name]);
+
+        return new self($newData);
     }
 
     /**

src/Model/Entity.php

@@ -2,7 +2,7 @@
 
 namespace Tgallice\Wit\Model;
 
-class Entity implements \JsonSerializable
+final class Entity implements \JsonSerializable
 {
     const LOOKUP_TRAIT = 'trait';
 

src/Model/EntityValue.php

@@ -2,7 +2,7 @@
 
 namespace Tgallice\Wit\Model;
 
-class EntityValue implements \JsonSerializable
+final class EntityValue implements \JsonSerializable
 {
     /**
      * @var string

src/Model/Location.php

@@ -2,7 +2,7 @@
 
 namespace Tgallice\Wit\Model;
 
-class Location implements \JsonSerializable
+final class Location implements \JsonSerializable
 {
     /**
      * @var float