diff --git a/includes/Rest/EntryPoint.php b/includes/Rest/EntryPoint.php
index d5924f06c10..795999a55ca 100644
--- a/includes/Rest/EntryPoint.php
+++ b/includes/Rest/EntryPoint.php
@@ -6,8 +6,16 @@ use ExtensionRegistry;
 use MediaWiki\MediaWikiServices;
 use RequestContext;
 use Title;
+use WebResponse;
 
 class EntryPoint {
+	/** @var RequestInterface */
+	private $request;
+	/** @var WebResponse */
+	private $webResponse;
+	/** @var Router */
+	private $router;
+
 	public static function main() {
 		// URL safety checks
 		global $wgRequest;
@@ -21,8 +29,8 @@ class EntryPoint {
 		RequestContext::getMain()->setTitle( $wgTitle );
 
 		$services = MediaWikiServices::getInstance();
-
 		$conf = $services->getMainConfig();
+
 		$request = new RequestFromGlobals( [
 			'cookiePrefix' => $conf->get( 'CookiePrefix' )
 		] );
@@ -36,20 +44,35 @@ class EntryPoint {
 			new ResponseFactory
 		);
 
-		$response = $router->execute( $request );
+		$entryPoint = new self(
+			$request,
+			$wgRequest->response(),
+			$router );
+		$entryPoint->execute();
+	}
 
-		$webResponse = $wgRequest->response();
-		$webResponse->header(
+	public function __construct( RequestInterface $request, WebResponse $webResponse,
+		Router $router
+	) {
+		$this->request = $request;
+		$this->webResponse = $webResponse;
+		$this->router = $router;
+	}
+
+	public function execute() {
+		$response = $this->router->execute( $this->request );
+
+		$this->webResponse->header(
 			'HTTP/' . $response->getProtocolVersion() . ' ' .
 			$response->getStatusCode() . ' ' .
 			$response->getReasonPhrase() );
 
 		foreach ( $response->getRawHeaderLines() as $line ) {
-			$webResponse->header( $line );
+			$this->webResponse->header( $line );
 		}
 
 		foreach ( $response->getCookies() as $cookie ) {
-			$webResponse->setCookie(
+			$this->webResponse->setCookie(
 				$cookie['name'],
 				$cookie['value'],
 				$cookie['expiry'],
diff --git a/tests/phpunit/includes/Rest/EntryPointTest.php b/tests/phpunit/includes/Rest/EntryPointTest.php
new file mode 100644
index 00000000000..4f87a70b4fe
--- /dev/null
+++ b/tests/phpunit/includes/Rest/EntryPointTest.php
@@ -0,0 +1,90 @@
+<?php
+
+namespace MediaWiki\Tests\Rest;
+
+use EmptyBagOStuff;
+use GuzzleHttp\Psr7\Uri;
+use GuzzleHttp\Psr7\Stream;
+use MediaWiki\Rest\Handler;
+use MediaWikiTestCase;
+use MediaWiki\Rest\EntryPoint;
+use MediaWiki\Rest\RequestData;
+use MediaWiki\Rest\ResponseFactory;
+use MediaWiki\Rest\Router;
+use WebResponse;
+
+/**
+ * @covers \MediaWiki\Rest\EntryPoint
+ * @covers \MediaWiki\Rest\Router
+ */
+class EntryPointTest extends MediaWikiTestCase {
+	private static $mockHandler;
+
+	private function createRouter() {
+		return new Router(
+			[ __DIR__ . '/testRoutes.json' ],
+			[],
+			'/rest',
+			new EmptyBagOStuff(),
+			new ResponseFactory() );
+	}
+
+	private function createWebResponse() {
+		return $this->getMockBuilder( WebResponse::class )
+			->setMethods( [ 'header' ] )
+			->getMock();
+	}
+
+	public static function mockHandlerHeader() {
+		return new class extends Handler {
+			public function execute() {
+				$response = $this->getResponseFactory()->create();
+				$response->setHeader( 'Foo', 'Bar' );
+				return $response;
+			}
+		};
+	}
+
+	public function testHeader() {
+		$webResponse = $this->createWebResponse();
+		$webResponse->expects( $this->any() )
+			->method( 'header' )
+			->withConsecutive(
+				[ 'HTTP/1.1 200 OK', true, null ],
+				[ 'Foo: Bar', true, null ]
+			);
+
+		$entryPoint = new EntryPoint(
+			new RequestData( [ 'uri' => new Uri( '/rest/mock/EntryPoint/header' ) ] ),
+			$webResponse,
+			$this->createRouter() );
+		$entryPoint->execute();
+		$this->assertTrue( true );
+	}
+
+	public static function mockHandlerBodyRewind() {
+		return new class extends Handler {
+			public function execute() {
+				$response = $this->getResponseFactory()->create();
+				$stream = new Stream( fopen( 'php://memory', 'w+' ) );
+				$stream->write( 'hello' );
+				$response->setBody( $stream );
+				return $response;
+			}
+		};
+	}
+
+	/**
+	 * Make sure EntryPoint rewinds a seekable body stream before reading.
+	 */
+	public function testBodyRewind() {
+		$entryPoint = new EntryPoint(
+			new RequestData( [ 'uri' => new Uri( '/rest/mock/EntryPoint/bodyRewind' ) ] ),
+			$this->createWebResponse(),
+			$this->createRouter() );
+		ob_start();
+		$entryPoint->execute();
+		$this->assertSame( 'hello', ob_get_clean() );
+	}
+
+}
diff --git a/tests/phpunit/includes/Rest/Handler/HelloHandlerTest.php b/tests/phpunit/includes/Rest/Handler/HelloHandlerTest.php
index 9719f9ea67d..afbaafb7573 100644
--- a/tests/phpunit/includes/Rest/Handler/HelloHandlerTest.php
+++ b/tests/phpunit/includes/Rest/Handler/HelloHandlerTest.php
@@ -49,7 +49,7 @@ class HelloHandlerTest extends MediaWikiTestCase {
 	/** @dataProvider provideTestViaRouter */
 	public function testViaRouter( $requestInfo, $responseInfo ) {
 		$router = new Router(
-			[ __DIR__ . '/testRoutes.json' ],
+			[ __DIR__ . '/../testRoutes.json' ],
 			[],
 			'/rest',
 			new EmptyBagOStuff(),
diff --git a/tests/phpunit/includes/Rest/Handler/testRoutes.json b/tests/phpunit/includes/Rest/Handler/testRoutes.json
deleted file mode 100644
index 6b440f77593..00000000000
--- a/tests/phpunit/includes/Rest/Handler/testRoutes.json
+++ /dev/null
@@ -1,6 +0,0 @@
-[
-	{
-		"path": "/user/{name}/hello",
-		"class": "MediaWiki\\Rest\\Handler\\HelloHandler"
-	}
-]
diff --git a/tests/phpunit/includes/Rest/testRoutes.json b/tests/phpunit/includes/Rest/testRoutes.json
new file mode 100644
index 00000000000..7e43bb0c5df
--- /dev/null
+++ b/tests/phpunit/includes/Rest/testRoutes.json
@@ -0,0 +1,14 @@
+[
+	{
+		"path": "/user/{name}/hello",
+		"class": "MediaWiki\\Rest\\Handler\\HelloHandler"
+	},
+	{
+		"path": "/mock/EntryPoint/header",
+		"factory": "MediaWiki\\Tests\\Rest\\EntryPointTest::mockHandlerHeader"
+	},
+	{
+		"path": "/mock/EntryPoint/bodyRewind",
+		"factory": "MediaWiki\\Tests\\Rest\\EntryPointTest::mockHandlerBodyRewind"
+	}
+]