diff --cc core/modules/rest/tests/src/Functional/Views/StyleSerializerTest.php
index cb9fee24a2,8078eecb02..0000000000
--- a/core/modules/rest/tests/src/Functional/Views/StyleSerializerTest.php
+++ b/core/modules/rest/tests/src/Functional/Views/StyleSerializerTest.php
@@@ -200,13 -213,35 +203,35 @@@ class StyleSerializerTest extends ViewT
      ]);
      $view->save();
      $expected = $serializer->serialize($entities, 'json');
 -    $actual_json = $this->drupalGetWithFormat('test/serialize/entity', 'json');
 +    $actual_json = $this->drupalGet('test/serialize/entity', ['query' => ['_format' => 'json']]);
      $this->assertIdentical($actual_json, $expected, 'The expected JSON output was found.');
      $expected = $serializer->serialize($entities, 'xml');
 -    $actual_xml = $this->drupalGetWithFormat('test/serialize/entity', 'xml');
 -    $this->assertIdentical($actual_xml, $expected, 'The expected XML output was found.');
 +    $actual_xml = $this->drupalGet('test/serialize/entity', ['query' => ['_format' => 'xml']]);
 +    $this->assertSame(trim($expected), $actual_xml);
    }
  
+   /**
+    * Verifies REST export views work on the same path as a page display.
+    */
+   public function testSharedPagePath() {
+     // Test with no format as well as html explicitly.
+     $this->drupalGet('test/serialize/shared');
+     $this->assertResponse(200);
+     $this->assertHeader('content-type', 'text/html; charset=UTF-8');
+ 
 -    $this->drupalGetWithFormat('test/serialize/shared', 'html');
++    $this->drupalGet('test/serialize/shared', ['query' => ['_format' => 'html']]);
+     $this->assertResponse(200);
+     $this->assertHeader('content-type', 'text/html; charset=UTF-8');
+ 
 -    $this->drupalGetWithFormat('test/serialize/shared', 'json');
++    $this->drupalGet('test/serialize/shared', ['query' => ['_format' => 'json']]);
+     $this->assertResponse(200);
+     $this->assertHeader('content-type', 'application/json');
+ 
 -    $this->drupalGetWithFormat('test/serialize/shared', 'xml');
++    $this->drupalGet('test/serialize/shared', ['query' => ['_format' => 'xml']]);
+     $this->assertResponse(200);
+     $this->assertHeader('content-type', 'text/xml; charset=UTF-8');
+   }
+ 
    /**
     * Verifies site maintenance mode functionality.
     */
@@@ -353,19 -393,18 +383,18 @@@
      $this->drupalPostForm($style_options, ['style_options[formats][json]' => 'json'], t('Apply'));
      $this->drupalPostForm(NULL, [], t('Save'));
  
-     // Should return a 200.
-     // @todo This should be fixed when we have better content negotiation.
-     $this->drupalGet('test/serialize/field');
-     $this->assertHeader('content-type', 'application/json');
-     $this->assertResponse(200, 'A 200 response was returned when any format was requested.');
- 
-     // Should return a 200. Emulates a sample Firefox header.
+     // Should return a 406. Emulates a sample Firefox header.
      $this->drupalGet('test/serialize/field', [], ['Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8']);
-     $this->assertHeader('content-type', 'application/json');
-     $this->assertResponse(200, 'A 200 response was returned when a browser accept header was requested.');
+     $this->assertHeader('content-type', 'text/html; charset=UTF-8');
+     $this->assertResponse(406, 'A 406 response was returned when a browser accept header was requested.');
+ 
+     // Should return a 406.
+     $this->drupalGetWithFormat('test/serialize/field', 'html');
+     $this->assertHeader('content-type', 'text/html; charset=UTF-8');
+     $this->assertResponse(406, 'A 406 response was returned when HTML was requested.');
  
      // Should return a 200.
 -    $this->drupalGetWithFormat('test/serialize/field', 'json');
 +    $this->drupalGet('test/serialize/field', ['query' => ['_format' => 'json']]);
      $this->assertHeader('content-type', 'application/json');
      $this->assertResponse(200, 'A 200 response was returned when JSON was requested.');
      $headers = $this->drupalGetHeaders();
@@@ -375,15 -414,9 +404,15 @@@
      $this->assertHeader('content-type', 'text/xml; charset=UTF-8');
      $this->assertResponse(200, 'A 200 response was returned when XML was requested');
      $headers = $this->drupalGetHeaders();
 -    $this->assertTrue(strpos($headers['content-type'], 'text/xml') !== FALSE, 'The header Content-type is correct.');
 +    $this->assertSame(['text/xml; charset=UTF-8'], $headers['Content-Type']);
 +    // Should return a 406.
 +    $this->drupalGet('test/serialize/field', ['query' => ['_format' => 'html']]);
 +    // We want to show the first format by default, see
 +    // \Drupal\rest\Plugin\views\style\Serializer::render.
 +    $this->assertHeader('content-type', 'application/json');
 +    $this->assertResponse(200, 'A 200 response was returned when HTML was requested.');
  
-     // Now configure now format, so all of them should be allowed.
+     // Now configure no format, so all of them should be allowed.
      $this->drupalPostForm($style_options, ['style_options[formats][json]' => '0', 'style_options[formats][xml]' => '0'], t('Apply'));
  
      // Should return a 200.
@@@ -391,15 -424,13 +420,13 @@@
      $this->assertHeader('content-type', 'application/json');
      $this->assertResponse(200, 'A 200 response was returned when JSON was requested.');
      // Should return a 200.
 -    $this->drupalGetWithFormat('test/serialize/field', 'xml');
 +    $this->drupalGet('test/serialize/field', ['query' => ['_format' => 'xml']]);
      $this->assertHeader('content-type', 'text/xml; charset=UTF-8');
      $this->assertResponse(200, 'A 200 response was returned when XML was requested');
-     // Should return a 200.
+     // Should return a 406 for HTML.
 -    $this->drupalGetWithFormat('test/serialize/field', 'html');
 +    $this->drupalGet('test/serialize/field', ['query' => ['_format' => 'html']]);
-     // We want to show the first format by default, see
-     // \Drupal\rest\Plugin\views\style\Serializer::render.
-     $this->assertHeader('content-type', 'application/json');
-     $this->assertResponse(200, 'A 200 response was returned when HTML was requested.');
+     $this->assertHeader('content-type', 'text/html; charset=UTF-8');
+     $this->assertResponse(406, 'A 406 response was returned when HTML was requested.');
    }
  
    /**
@@@ -597,8 -628,7 +624,8 @@@
      $this->assertResponse(200);
      // Check if we receive the expected result.
      $result = $this->xpath('//div[@id="views-live-preview"]/pre');
 -    $this->assertIdentical($this->drupalGetWithFormat('test/serialize/field', 'json'), (string) $result[0], 'The expected JSON preview output was found.');
 +    $json_preview = $result[0]->getText();
-     $this->assertSame($json_preview, $this->drupalGet('test/serialize/field'), 'The expected JSON preview output was found.');
++    $this->assertSame($json_preview, $this->drupalGet('test/serialize/field', ['query' => ['_format' => 'json']]), 'The expected JSON preview output was found.');
    }
  
    /**