Improve header parsing and add tests (#1600)

Author: cleptric

src/Util/Http.php

@@ -40,15 +40,25 @@ public static function getRequestHeaders(Dsn $dsn, string $sdkIdentifier, string
 
     /**
      * @param string[][] $headers
+     *
+     * @param-out string[][] $headers
      */
-    public static function parseResponseHeaders(string $headerLine, &$headers): int
+    public static function parseResponseHeaders(string $headerLine, array &$headers): int
     {
         if (false === strpos($headerLine, ':')) {
             return \strlen($headerLine);
         }
 
-        [$key, $value] = explode(':', trim($headerLine), 2);
-        $headers[trim($key)] = trim($value);
+        [$name, $value] = explode(':', trim($headerLine), 2);
+
+        $name = trim($name);
+        $value = trim($value);
+
+        if (isset($headers[$name])) {
+            $headers[$name][] = $value;
+        } else {
+            $headers[$name] = (array) $value;
+        }
 
         return \strlen($headerLine);
     }

tests/Util/HttpTest.php

@@ -40,4 +40,42 @@ public static function getRequestHeadersDataProvider(): \Generator
             ],
         ];
     }
+
+    /**
+     * @dataProvider parseResponseHeadersDataProvider
+     */
+    public function testParseResponseHeaders(string $headerline, $expectedResult): void
+    {
+        $responseHeaders = [];
+
+        Http::parseResponseHeaders($headerline, $responseHeaders);
+
+        $this->assertSame($expectedResult, $responseHeaders);
+    }
+
+    public static function parseResponseHeadersDataProvider(): \Generator
+    {
+        yield [
+            'Content-Type: application/json',
+            [
+                'Content-Type' => [
+                    'application/json',
+                ],
+            ],
+        ];
+
+        yield [
+            'X-Sentry-Rate-Limits: 60:transaction:key,2700:default;error;security:organization',
+            [
+                'X-Sentry-Rate-Limits' => [
+                    '60:transaction:key,2700:default;error;security:organization',
+                ],
+            ],
+        ];
+
+        yield [
+            'Invalid',
+            [],
+        ];
+    }
 }