Assert values according to PSR standard

src/MessageTrait.php

@@ -66,6 +66,7 @@ public function getHeaderLine($header)
 
     public function withHeader($header, $value)
     {
+        $this->assertHeader($header);
         if (!is_array($value)) {
             $value = [$value];
         }
@@ -85,7 +86,12 @@ public function withHeader($header, $value)
 
     public function withAddedHeader($header, $value)
     {
+        $this->assertHeader($header);
         if (!is_array($value)) {
+            if (!is_string($value)) {
+                throw new \InvalidArgumentException('Header value must be a string or an array of strings.');
+            }
+
             $value = [$value];
         }
 
@@ -145,6 +151,10 @@ private function setHeaders(array $headers)
         $this->headerNames = $this->headers = [];
         foreach ($headers as $header => $value) {
             if (!is_array($value)) {
+                if (!is_string($value)) {
+                    throw new \InvalidArgumentException('Header value must be a string or an array of strings.');
+                }
+
                 $value = [$value];
             }
 
@@ -180,4 +190,14 @@ private function trimHeaderValues(array $values)
             return trim($value, " \t");
         }, $values);
     }
+
+    /**
+     * @param string $header
+     */
+    private function assertHeader($header)
+    {
+        if (!is_string($header) || $header === '') {
+            throw new \InvalidArgumentException('Header must be a non empty string');
+        }
+    }
 }

src/Request.php

@@ -36,6 +36,7 @@ public function __construct(
         $body = null,
         $version = '1.1'
     ) {
+        $this->assertMethod($method);
         if (!($uri instanceof UriInterface)) {
             $uri = new Uri($uri);
         }
@@ -91,6 +92,7 @@ public function getMethod()
 
     public function withMethod($method)
     {
+        $this->assertMethod($method);
         $new = clone $this;
         $new->method = strtoupper($method);
         return $new;
@@ -139,4 +141,14 @@ private function updateHostFromUri()
         // See: http://tools.ietf.org/html/rfc7230#section-5.4
         $this->headers = [$header => [$host]] + $this->headers;
     }
+
+    /**
+     * @param string $method
+     */
+    private function assertMethod($method)
+    {
+        if (!is_string($method) || $method === '') {
+            throw new \InvalidArgumentException('Method should be a non empty string.');
+        }
+    }
 }

src/Response.php

@@ -93,9 +93,9 @@ public function __construct(
         $version = '1.1',
         $reason = null
     ) {
-        if (filter_var($status, FILTER_VALIDATE_INT) === false) {
-            throw new \InvalidArgumentException('Status code must be an integer value.');
-        }
+        $this->assertStatusCodeIsInteger($status);
+        $status = (int) $status;
+        $this->assertStatusCodeRange($status);
 
         $this->statusCode = (int) $status;
 
@@ -125,12 +125,36 @@ public function getReasonPhrase()
 
     public function withStatus($code, $reasonPhrase = '')
     {
+        $this->assertStatusCodeIsInteger($code);
+        $code = (int) $code;
+        $this->assertStatusCodeRange($code);
+
         $new = clone $this;
-        $new->statusCode = (int) $code;
+        $new->statusCode = $code;
         if ($reasonPhrase == '' && isset(self::$phrases[$new->statusCode])) {
             $reasonPhrase = self::$phrases[$new->statusCode];
         }
         $new->reasonPhrase = $reasonPhrase;
         return $new;
     }
+
+    /**
+     * @param int $statusCode
+     */
+    private function assertStatusCodeIsInteger($statusCode)
+    {
+        if (filter_var($statusCode, FILTER_VALIDATE_INT) === false) {
+            throw new \InvalidArgumentException('Status code must be an integer value.');
+        }
+    }
+
+    /**
+     * @param int $statusCode
+     */
+    private function assertStatusCodeRange($statusCode)
+    {
+        if ($statusCode < 100 || $statusCode > 600) {
+            throw new \InvalidArgumentException('Status code must be an integer value between 1xx and 5xx.');
+        }
+    }
 }