diff --git a/core/modules/search/tests/src/Functional/SearchBlockTest.php b/core/modules/search/tests/src/Functional/SearchBlockTest.php
index 3c6b746017d6ceb401e3d634880497c57f13fc7b..49427b2ea5522beab784fb10ecd4aca5b0d523f5 100644
--- a/core/modules/search/tests/src/Functional/SearchBlockTest.php
+++ b/core/modules/search/tests/src/Functional/SearchBlockTest.php
@@ -47,14 +47,14 @@ public function testSearchFormBlock() {
 
     // Test a normal search via the block form, from the front page.
     $terms = ['keys' => 'test'];
-    $this->submitGetForm('', $terms, t('Search'));
+    $this->drupalPostForm('', $terms, t('Search'));
     $this->assertResponse(200);
     $this->assertText('Your search yielded no results');
 
     // Test a search from the block on a 404 page.
     $this->drupalGet('foo');
     $this->assertResponse(404);
-    $this->submitGetForm(NULL, $terms, t('Search'));
+    $this->drupalPostForm(NULL, $terms, t('Search'));
     $this->assertResponse(200);
     $this->assertText('Your search yielded no results');
 
@@ -62,7 +62,7 @@ public function testSearchFormBlock() {
     $visibility['request_path']['pages'] = 'search';
     $block->setVisibilityConfig('request_path', $visibility['request_path']);
 
-    $this->submitGetForm('', $terms, t('Search'));
+    $this->drupalPostForm('', $terms, t('Search'));
     $this->assertResponse(200);
     $this->assertText('Your search yielded no results');
 
@@ -78,7 +78,7 @@ public function testSearchFormBlock() {
 
     // Test an empty search via the block form, from the front page.
     $terms = ['keys' => ''];
-    $this->submitGetForm('', $terms, t('Search'));
+    $this->drupalPostForm('', $terms, t('Search'));
     $this->assertResponse(200);
     $this->assertText('Please enter some keywords');
 
@@ -92,16 +92,16 @@ public function testSearchFormBlock() {
 
     // Test that after entering a too-short keyword in the form, you can then
     // search again with a longer keyword. First test using the block form.
-    $this->submitGetForm('node', ['keys' => $this->randomMachineName(1)], t('Search'));
+    $this->drupalPostForm('node', ['keys' => $this->randomMachineName(1)], t('Search'));
     $this->assertText('You must include at least one keyword to match in the content', 'Keyword message is displayed when searching for short word');
     $this->assertNoText(t('Please enter some keywords'), 'With short word entered, no keywords message is not displayed');
-    $this->submitGetForm(NULL, ['keys' => $this->randomMachineName()], t('Search'), 'search-block-form');
+    $this->drupalPostForm(NULL, ['keys' => $this->randomMachineName()], t('Search'), [], 'search-block-form');
     $this->assertNoText('You must include at least one keyword to match in the content', 'Keyword message is not displayed when searching for long word after short word search');
 
     // Same test again, using the search page form for the second search this
     // time.
-    $this->submitGetForm('node', ['keys' => $this->randomMachineName(1)], t('Search'));
-    $this->drupalPostForm(NULL, ['keys' => $this->randomMachineName()], t('Search'), [], [], 'search-form');
+    $this->drupalPostForm('node', ['keys' => $this->randomMachineName(1)], t('Search'));
+    $this->drupalPostForm(NULL, ['keys' => $this->randomMachineName()], t('Search'), [], 'search-form');
     $this->assertNoText('You must include at least one keyword to match in the content', 'Keyword message is not displayed when searching for long word after short word search');
 
   }
diff --git a/core/modules/search/tests/src/Functional/SearchConfigSettingsFormTest.php b/core/modules/search/tests/src/Functional/SearchConfigSettingsFormTest.php
index f404f8f1335c5a52c432335008829e26f2ce1177..2692a37a6a1449b729982b17ced362f99e8f5152 100644
--- a/core/modules/search/tests/src/Functional/SearchConfigSettingsFormTest.php
+++ b/core/modules/search/tests/src/Functional/SearchConfigSettingsFormTest.php
@@ -174,7 +174,7 @@ public function testSearchModuleDisabling() {
       // Run a search from the search block on the node page. Verify you get
       // to this plugin's search results page.
       $terms = ['keys' => $info['keys']];
-      $this->submitGetForm('node', $terms, t('Search'));
+      $this->drupalPostForm('node', $terms, t('Search'));
       $current = $this->getURL();
       $expected = \Drupal::url('search.view_' . $entity->id(), [], ['query' => ['keys' => $info['keys']], 'absolute' => TRUE]);
       $this->assertEqual($current, $expected, 'Block redirected to right search page');
diff --git a/core/modules/search/tests/src/Functional/SearchTestBase.php b/core/modules/search/tests/src/Functional/SearchTestBase.php
index 570658de06ac379ec6ac29c4305dd9a21da088fc..e426a92a44f159327de75fb39898450c5c90ae4e 100644
--- a/core/modules/search/tests/src/Functional/SearchTestBase.php
+++ b/core/modules/search/tests/src/Functional/SearchTestBase.php
@@ -41,26 +41,14 @@ protected function setUp() {
    * @param string $form_html_id
    *   (optional) HTML ID of the form, to disambiguate.
    *
-   * @throws \Behat\Mink\Exception\ElementNotFoundException
+   * @deprecated in Drupal 8.6.x, to be removed before Drupal 9.0.x. Use
+   *   \Drupal\Tests\BrowserTestBase::drupalPostForm() instead.
    *
-   * @todo: Replace after https://www.drupal.org/project/drupal/issues/2887411
+   * @see https://www.drupal.org/node/2979950
    */
   protected function submitGetForm($path, $edit, $submit, $form_html_id = NULL) {
-    if (isset($path)) {
-      $this->drupalGet($path);
-    }
-
-    $page = $this->getSession()->getPage();
-    $wrapper = $page;
-    if ($form_html_id) {
-      $wrapper = $page->find('css', '#' . $form_html_id);
-    }
-    $button = $wrapper->findButton($submit);
-    $form = $this->assertSession()->elementExists('xpath', './ancestor::form', $button);
-    foreach ($edit as $selector => $value) {
-      $form->fillField($selector, $value);
-    }
-    $button->press();
+    @trigger_error(__CLASS__ . '::' . __FUNCTION__ . '() is deprecated in Drupal 8.6.x, for removal before the Drupal 9.0.0 release. Use \Drupal\Tests\BrowserTestBase::drupalPostForm() instead. See https://www.drupal.org/node/2979950.', E_USER_DEPRECATED);
+    $this->drupalPostForm($path, $edit, $submit, [], $form_html_id);
   }
 
 }
diff --git a/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php b/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
index 2e8562b3f158e61f82a7ce16f5d10c90dedf0b16..92a000201871db98ae96a441f4f4200c62969359 100644
--- a/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
+++ b/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
@@ -23,7 +23,7 @@ class BrowserTestBaseTest extends BrowserTestBase {
    *
    * @var array
    */
-  public static $modules = ['test_page_test', 'form_test', 'system_test'];
+  public static $modules = ['test_page_test', 'form_test', 'system_test', 'node'];
 
   /**
    * Tests basic page test.
@@ -111,6 +111,15 @@ public function testForm() {
     // Test drupalPostForm() with no-html response.
     $values = Json::decode($this->drupalPostForm('form_test/form-state-values-clean', [], t('Submit')));
     $this->assertTrue(1000, $values['beer']);
+
+    // Test drupalPostForm() with form by HTML id.
+    $this->drupalCreateContentType(['type' => 'page']);
+    $this->drupalLogin($this->drupalCreateUser(['create page content']));
+    $this->drupalGet('form-test/two-instances-of-same-form');
+    $this->getSession()->getPage()->fillField('edit-title-0-value', 'form1');
+    $this->getSession()->getPage()->fillField('edit-title-0-value--2', 'form2');
+    $this->drupalPostForm(NULL, [], 'Save', [], 'node-page-form--2');
+    $this->assertSession()->pageTextContains('Page form2 has been created.');
   }
 
   /**
diff --git a/core/tests/Drupal/Tests/BrowserTestBase.php b/core/tests/Drupal/Tests/BrowserTestBase.php
index 290be1a5cf015dd0a3e7cf580542952705ec0d98..4aaf6c5417b17eb5138c5f92227924a0598049b4 100644
--- a/core/tests/Drupal/Tests/BrowserTestBase.php
+++ b/core/tests/Drupal/Tests/BrowserTestBase.php
@@ -924,7 +924,7 @@ protected function submitForm(array $edit, $submit, $form_html_id = NULL) {
   /**
    * Executes a form submission.
    *
-   * It will be done as usual POST request with Mink.
+   * It will be done as usual submit form with Mink.
    *
    * @param \Drupal\Core\Url|string $path
    *   Location of the post form. Either a Drupal path or an absolute path or
@@ -990,13 +990,20 @@ protected function submitForm(array $edit, $submit, $form_html_id = NULL) {
    *   POST data.
    * @param array $options
    *   Options to be forwarded to the url generator.
+   * @param string|null $form_html_id
+   *   (optional) HTML ID of the form to be submitted. On some pages
+   *   there are many identical forms, so just using the value of the submit
+   *   button is not enough. For example: 'trigger-node-presave-assign-form'.
+   *   Note that this is not the Drupal $form_id, but rather the HTML ID of the
+   *   form, which is typically the same thing but with hyphens replacing the
+   *   underscores.
    *
    * @return string
    *   (deprecated) The response content after submit form. It is necessary for
    *   backwards compatibility and will be removed before Drupal 9.0. You should
    *   just use the webAssert object for your assertions.
    */
-  protected function drupalPostForm($path, $edit, $submit, array $options = []) {
+  protected function drupalPostForm($path, $edit, $submit, array $options = [], $form_html_id = NULL) {
     if (is_object($submit)) {
       // Cast MarkupInterface objects to string.
       $submit = (string) $submit;
@@ -1012,7 +1019,7 @@ protected function drupalPostForm($path, $edit, $submit, array $options = []) {
       $this->drupalGet($path, $options);
     }
 
-    $this->submitForm($edit, $submit);
+    $this->submitForm($edit, $submit, $form_html_id);
 
     return $this->getSession()->getPage()->getContent();
   }