PSR-15 Middleware: made response validation optional, enabled by default

README.md

@@ -90,6 +90,8 @@ Validation of `\Psr\Http\Message\ResponseInterface` is a bit more complicated
 . Because you need not only YAML file and Response itself, but also you need 
 to know which operation this response belongs to (in terms of OpenAPI).
 
+Reponse validation is optional and is enabled by default. See [Skipping response validation](#skipping-response-validation)
+
 Example:
 
 ```php
@@ -194,6 +196,15 @@ You can use `->setCache($pool, $ttl)` call for both PSR-7 and PSR-15 builder in
 If you want take control over the cache key for schema item, or your cache does not support cache key generation by itself
 you can `->overrideCacheKey('my_custom_key')` to ensure cache uses key you want.
 
+### Skipping response validation
+If you want to skip response validation and only validate requests, you can call `->shouldValidateResponse(false)` method on the builder like this:
+```php
+$psr15Middleware = (new \OpenAPIValidation\PSR15\ValidationMiddlewareBuilder)
+    ->fromYamlFile($yamlFile)
+    ->shouldValidateResponse(false)
+    ->getValidationMiddleware();
+```
+
 ### Standalone OpenAPI Validator
 The package contains a standalone validator which can validate any data 
 against an OpenAPI schema like this:

src/PSR15/ValidationMiddleware.php

@@ -18,10 +18,10 @@ final class ValidationMiddleware implements MiddlewareInterface
 {
     /** @var ServerRequestValidator */
     private $requestValidator;
-    /** @var ResponseValidator */
+    /** @var ResponseValidator|null */
     private $responseValidator;
 
-    public function __construct(ServerRequestValidator $requestValidator, ResponseValidator $responseValidator)
+    public function __construct(ServerRequestValidator $requestValidator, ?ResponseValidator $responseValidator = null)
     {
         $this->requestValidator  = $requestValidator;
         $this->responseValidator = $responseValidator;
@@ -46,11 +46,13 @@ public function process(ServerRequestInterface $request, RequestHandlerInterface
         // 2. Process request
         $response = $handler->handle($request);
 
-        // 3. Validate response
-        try {
-            $this->responseValidator->validate($matchedOASOperation, $response);
-        } catch (ValidationFailed $e) {
-            throw InvalidResponseMessage::because($e);
+        if ($this->responseValidator !== null) {
+            // 3. Validate response
+            try {
+                $this->responseValidator->validate($matchedOASOperation, $response);
+            } catch (ValidationFailed $e) {
+                throw InvalidResponseMessage::because($e);
+            }
         }
 
         return $response;

src/PSR15/ValidationMiddlewareBuilder.php

@@ -9,11 +9,24 @@
 
 class ValidationMiddlewareBuilder extends ValidatorBuilder
 {
+    /** @var bool */
+    protected $shouldValidateResponse = true;
+
+    /**
+     * @return $this
+     */
+    public function shouldValidateResponse(bool $value): self
+    {
+        $this->shouldValidateResponse = $value;
+
+        return $this;
+    }
+
     public function getValidationMiddleware(): MiddlewareInterface
     {
         return new ValidationMiddleware(
             $this->getServerRequestValidator(),
-            $this->getResponseValidator()
+            $this->shouldValidateResponse ? $this->getResponseValidator() : null
         );
     }
 }

tests/PSR15/ValidationMiddlewareTest.php

@@ -59,4 +59,24 @@ public function testItReturnsExpectedException(
         $this->expectException($expectedExceptionType);
         $middleware->process($serverRequest, $handler);
     }
+
+    public function testItDoesNotValidateResponseIfNoValidatorConfigured(): void
+    {
+        $this->expectNotToPerformAssertions();
+
+        $builder = (new ValidatorBuilder())->fromYamlFile($this->apiSpecFile);
+
+        $middleware = new ValidationMiddleware(
+            $builder->getServerRequestValidator(),
+            null
+        );
+
+        $handler = $this->createMock(RequestHandlerInterface::class);
+        $handler
+            ->method('handle')
+            ->willReturn(new Response());
+
+        // no exception thrown
+        $middleware->process($this->makeGoodServerRequest('/read', 'get'), $handler);
+    }
 }