fix: latest redirected response overwrites existing response headers

src/RequestResolver.php

@@ -180,6 +180,12 @@ private function writeHeader(
 		$i = $this->getIndex($ch);
 		$headerLine = trim($rawHeader);
 
+		if($this->isStartOfNewHeaderBlock($i, $headerLine)) {
+			$this->headerList[$i] = "";
+			$this->responseList[$i] = new Response();
+			$this->responseList[$i]->startDeferredResponse($this->curlList[$i]);
+		}
+
 // If $headerLine is empty, it represents the last line before the body starts.
 // HTTP headers always end on an empty line.
 // See https://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html
@@ -218,6 +224,11 @@ private function writeHeader(
 		return strlen($rawHeader);
 	}
 
+	private function isStartOfNewHeaderBlock(int $index, string $headerLine):bool {
+		return str_starts_with(strtolower($headerLine), "http/")
+			&& trim($this->headerList[$index]) !== "";
+	}
+
 	private function writeBody(CurlHandle|CurlInterface $ch, string $content):int {
 		$i = $this->getIndex($ch);
 

test/phpunit/Helper/ResponseSimulator.php

@@ -75,8 +75,21 @@ static public function hasStarted():bool {
 	}
 
 	static public function sendChunk(CurlInterface $ch):int {
-// TODO: If the URL is test://should-redirect, send the redirect header here
 		$url = $ch->getInfo(CURLINFO_EFFECTIVE_URL);
+		if($url === "test://should-follow-redirect" && !self::$redirectAdded) {
+			self::$headerBuffer = [
+				"HTTP/1.1 303 See Other\r\n",
+				"Content-Type: text/html\r\n",
+				"Location: /redirected\r\n",
+				"\r\n",
+				"HTTP/1.1 200 OK\r\n",
+				"Content-Type: application/json\r\n",
+				"X-Final-Response: true\r\n",
+				"\r\n",
+			];
+			self::$bodyBuffer = "{}";
+			self::$redirectAdded = true;
+		}
 		if($url === "test://should-redirect") {
 			$locationRedirect = "Location: /redirected\r\n";
 			if(!self::$redirectAdded) {

test/phpunit/HttpTest.php

@@ -148,6 +148,23 @@ public function testFetchRedirectError():void {
 		self::assertInstanceOf(FetchException::class, $actualRejection);
 	}
 
+	/** @runInSeparateProcess */
+	public function testFollowedRedirectOnlyExposesFinalResponseHeaders():void {
+		$sut = new Http(
+			[],
+			0.01,
+			TestCurl::class,
+			TestCurlMulti::class
+		);
+
+		$response = $sut->awaitFetch("test://should-follow-redirect");
+
+		self::assertSame(200, $response->status);
+		self::assertSame("application/json", $response->getHeaderLine("Content-Type"));
+		self::assertSame("true", $response->getHeaderLine("X-Final-Response"));
+		self::assertSame("", $response->getHeaderLine("Location"));
+	}
+
 	/** @runInSeparateProcess */
 	public function testAwaitFetch():void {
 		$http = new Http(