Fix early echo of stream responses.

Calling body() now invokes the callback which outputs and sends headers.
That isn't what we want to do when we're trying to inject HTML. Instead
use getBody() to access the stream object.

src/ToolbarService.php

@@ -210,8 +210,8 @@ public function injectScripts($row, $response)
         if (strpos($response->type(), 'html') === false) {
             return $response;
         }
-        $body = $response->body();
-        if (!is_string($body)) {
+        $body = $response->getBody();
+        if (!$body->isSeekable()) {
             return $response;
         }
         $pos = strrpos($body, '</body>');

tests/TestCase/Routing/Filter/DebugBarFilterTest.php

@@ -130,13 +130,13 @@ public function testAfterDispatchIgnoreStreamBodies()
             'type' => 'text/html',
         ]);
         $response->body(function () {
-            echo 'I am a teapot!';
+            return 'I am a teapot!';
         });
 
         $bar = new DebugBarFilter($this->events, []);
         $event = new Event('Dispatcher.afterDispatch', $bar, compact('request', 'response'));
         $bar->afterDispatch($event);
-        $this->assertInstanceOf('Closure', $response->body());
+        $this->assertEquals('I am a teapot!', $response->body());
     }
 
     /**

tests/TestCase/ToolbarServiceTest.php

@@ -198,16 +198,15 @@ public function testInjectScriptsStreamBodies()
             'type' => 'text/html',
         ]);
         $response->body(function () {
-            echo 'I am a teapot!';
+            return 'I am a teapot!';
         });
 
         $bar = new ToolbarService($this->events, []);
         $row = new RequestEntity(['id' => 'abc123']);
 
         $result = $bar->injectScripts($row, $response);
         $this->assertInstanceOf('Cake\Network\Response', $result);
-        $this->assertInstanceOf('Closure', $result->body());
-        $this->assertInstanceOf('Closure', $response->body());
+        $this->assertEquals('I am a teapot!', $result->body());
     }