diff --git a/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php b/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
index d9df046..7c3b3a9 100644
--- a/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
+++ b/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
@@ -3,6 +3,7 @@
 namespace Drupal\FunctionalTests;
 
 use Behat\Mink\Exception\ExpectationException;
+use Drupal\Component\Serialization\Json;
 use Drupal\Component\Utility\Html;
 use Drupal\Core\Url;
 use Drupal\Tests\BrowserTestBase;
@@ -106,6 +107,10 @@ public function testForm() {
     $this->drupalPostForm('form-test/object-builder', NULL, 'Save');
     $value = $config_factory->get('form_test.object')->get('bananas');
     $this->assertSame('', $value);
+
+    // Test drupalPostForm() with no-html response.
+    $values = Json::decode($this->drupalPostForm('form_test/form-state-values-clean', [], t('Submit')));
+    $this->assertTrue(1000, $values['beer']);
   }
 
   /**
diff --git a/core/tests/Drupal/Tests/BrowserTestBase.php b/core/tests/Drupal/Tests/BrowserTestBase.php
index 91a10cd..9a754ad 100644
--- a/core/tests/Drupal/Tests/BrowserTestBase.php
+++ b/core/tests/Drupal/Tests/BrowserTestBase.php
@@ -922,7 +922,7 @@ protected function submitForm(array $edit, $submit, $form_html_id = NULL) {
    *   Options to be forwarded to the url generator.
    *
    * @return string
-   *   The HTML of the rendered page.
+   *   The response content after submit form.
    */
   protected function drupalPostForm($path, $edit, $submit, array $options = []) {
     if (is_object($submit)) {
@@ -942,6 +942,9 @@ protected function drupalPostForm($path, $edit, $submit, array $options = []) {
 
     $this->submitForm($edit, $submit);
 
+    // Returns response content for BC purposes. Feel free to use the webAssert
+    // object for your assertions.
+    // @see \Drupal\simpletest\WebTestBase::drupalPostForm()
     return $this->getSession()->getPage()->getContent();
   }