Consider empty requestBody as valid if not required

src/PSR7/Exception/Validation/InvalidBody.php

@@ -46,4 +46,12 @@ public static function becauseBodyIsNotValidJson(string $error, OperationAddress
 
         return $exception;
     }
+
+    public static function becauseOfMissingRequiredBody(OperationAddress $addr): self
+    {
+        $exception          = static::fromAddr($addr);
+        $exception->message = sprintf('Required body is missing for %s', $addr);
+
+        return $exception;
+    }
 }

src/PSR7/SpecFinder.php

@@ -7,15 +7,14 @@
 use cebe\openapi\exceptions\TypeErrorException;
 use cebe\openapi\spec\Callback;
 use cebe\openapi\spec\Header as HeaderSpec;
-use cebe\openapi\spec\MediaType;
 use cebe\openapi\spec\OpenApi;
 use cebe\openapi\spec\Operation;
 use cebe\openapi\spec\Parameter;
 use cebe\openapi\spec\PathItem;
-use cebe\openapi\spec\Reference;
 use cebe\openapi\spec\Response as ResponseSpec;
 use cebe\openapi\spec\SecurityRequirement;
 use cebe\openapi\spec\SecurityScheme;
+use cebe\openapi\SpecBaseObject;
 use League\OpenAPIValidation\PSR7\Exception\NoCallback;
 use League\OpenAPIValidation\PSR7\Exception\NoOperation;
 use League\OpenAPIValidation\PSR7\Exception\NoPath;
@@ -171,23 +170,15 @@ public function findSecuritySchemesSpecs(): array
     }
 
     /**
-     * @return MediaType[]|Reference[]
-     *
      * @throws NoPath
      */
-    public function findBodySpec(OperationAddress $addr): array
+    public function findBodySpec(OperationAddress $addr): ?SpecBaseObject
     {
         if ($addr instanceof ResponseAddress || $addr instanceof CallbackResponseAddress) {
-            return $this->findResponseSpec($addr)->content;
-        }
-
-        $requestBody = $this->findOperationSpec($addr)->requestBody;
-
-        if (! $requestBody) {
-            return [];
+            return $this->findResponseSpec($addr);
         }
 
-        return $requestBody->content;
+        return $this->findOperationSpec($addr)->requestBody;
     }
 
     /**

src/PSR7/Validators/BodyValidator/BodyValidator.php

@@ -6,6 +6,8 @@
 
 use cebe\openapi\spec\MediaType;
 use cebe\openapi\spec\Reference;
+use cebe\openapi\spec\RequestBody;
+use League\OpenAPIValidation\PSR7\Exception\Validation\InvalidBody;
 use League\OpenAPIValidation\PSR7\Exception\Validation\InvalidHeaders;
 use League\OpenAPIValidation\PSR7\MessageValidator;
 use League\OpenAPIValidation\PSR7\OperationAddress;
@@ -39,6 +41,20 @@ public function validate(OperationAddress $addr, MessageInterface $message): voi
     {
         $mediaTypeSpecs = $this->finder->findBodySpec($addr);
 
+        if ($mediaTypeSpecs === null) {
+            return;
+        }
+
+        if ($mediaTypeSpecs instanceof RequestBody && $message->getBody()->getSize() === 0) {
+            if ($mediaTypeSpecs->required) {
+                throw InvalidBody::becauseOfMissingRequiredBody($addr);
+            }
+
+            return;
+        }
+
+        $mediaTypeSpecs = $mediaTypeSpecs->content;
+
         if (empty($mediaTypeSpecs)) {
             // edge case: if "content" keyword is not set (body can be anything as no expectations set)
             return;

tests/FromCommunity/OptionalRequestBodyTest.php

@@ -0,0 +1,88 @@
+<?php
+
+declare(strict_types=1);
+
+namespace League\OpenAPIValidation\Tests\FromCommunity;
+
+use GuzzleHttp\Psr7\ServerRequest;
+use League\OpenAPIValidation\PSR7\Exception\Validation\InvalidBody;
+use League\OpenAPIValidation\PSR7\ValidatorBuilder;
+use PHPUnit\Framework\TestCase;
+
+class OptionalRequestBodyTest extends TestCase
+{
+    public function testOptionalEmptyBodyIsValid(): void
+    {
+        $yaml = /** @lang yaml */
+            <<<'YAML'
+openapi: 3.0.0
+info:
+  title: Test API
+  version: '1.0'
+servers:
+  - url: 'http://localhost:8000'
+paths:
+  /api:
+    post:
+      requestBody:
+        content:
+          application/json:
+            schema:
+              properties:
+                name:
+                  type: string
+      responses:
+        '204':
+          description: No content
+YAML;
+
+        $validator = (new ValidatorBuilder())->fromYaml($yaml)->getServerRequestValidator();
+
+        $validator->validate(
+            new ServerRequest(
+                'POST',
+                '/api'
+            )
+        );
+
+        $this->addToAssertionCount(1);
+    }
+
+    public function testRequiredEmptyBodyThrowsException(): void
+    {
+        $yaml = /** @lang yaml */
+            <<<'YAML'
+openapi: 3.0.0
+info:
+  title: Test API
+  version: '1.0'
+servers:
+  - url: 'http://localhost:8000'
+paths:
+  /api:
+    post:
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              properties:
+                name:
+                  type: string
+      responses:
+        '204':
+          description: No content
+YAML;
+
+        $validator = (new ValidatorBuilder())->fromYaml($yaml)->getServerRequestValidator();
+
+        $this->expectException(InvalidBody::class);
+        $this->expectExceptionMessage('Required body is missing for Request [post /api]');
+        $validator->validate(
+            new ServerRequest(
+                'POST',
+                '/api'
+            )
+        );
+    }
+}