diff --git a/core/modules/entity_reference/tests/modules/entity_reference_autocomplete_test/entity_reference_autocomplete_test.info.yml b/core/modules/entity_reference/tests/modules/entity_reference_autocomplete_test/entity_reference_autocomplete_test.info.yml
new file mode 100644
index 0000000000..4d78cc81ff
--- /dev/null
+++ b/core/modules/entity_reference/tests/modules/entity_reference_autocomplete_test/entity_reference_autocomplete_test.info.yml
@@ -0,0 +1,6 @@
+name: 'Entity reference autocomplete test module'
+type: module
+description: 'For testing autocomplete functionality'
+core: 8.x
+package: Testing
+version: VERSION
diff --git a/core/modules/entity_reference/tests/modules/entity_reference_autocomplete_test/entity_reference_autocomplete_test.libraries.yml b/core/modules/entity_reference/tests/modules/entity_reference_autocomplete_test/entity_reference_autocomplete_test.libraries.yml
new file mode 100644
index 0000000000..0b2c1d4ce4
--- /dev/null
+++ b/core/modules/entity_reference/tests/modules/entity_reference_autocomplete_test/entity_reference_autocomplete_test.libraries.yml
@@ -0,0 +1,5 @@
+autocomplete_events:
+  js:
+    js/autocomplete_events.js: {}
+  dependencies:
+    - core/drupal.autocomplete
diff --git a/core/modules/entity_reference/tests/modules/entity_reference_autocomplete_test/entity_reference_autocomplete_test.module b/core/modules/entity_reference/tests/modules/entity_reference_autocomplete_test/entity_reference_autocomplete_test.module
new file mode 100644
index 0000000000..5e265ea3db
--- /dev/null
+++ b/core/modules/entity_reference/tests/modules/entity_reference_autocomplete_test/entity_reference_autocomplete_test.module
@@ -0,0 +1,15 @@
+<?php
+
+/**
+ * @file
+ * For testing entity reference autocomplete.
+ */
+
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Implements hook_form_BASE_FORM_ID_alter().
+ */
+function entity_reference_autocomplete_test_form_node_form_alter(&$form, FormStateInterface $form_state, $form_id) {
+  $form['#attached']['library'][] = 'entity_reference_autocomplete_test/autocomplete_events';
+}
diff --git a/core/modules/entity_reference/tests/modules/entity_reference_autocomplete_test/js/autocomplete_events.es6.js b/core/modules/entity_reference/tests/modules/entity_reference_autocomplete_test/js/autocomplete_events.es6.js
new file mode 100644
index 0000000000..a64ec6f943
--- /dev/null
+++ b/core/modules/entity_reference/tests/modules/entity_reference_autocomplete_test/js/autocomplete_events.es6.js
@@ -0,0 +1,129 @@
+/**
+ * @file
+ * Attaches listeners for testing autocomplete events.
+ */
+
+(($, Drupal) => {
+  /**
+   * Checks if the argument has the expected properties of the ui object passed
+   *   by jQueryUI's autocomplete events.
+   *
+   * @param {object} ui
+   *   An object with the contents of the selected option.
+   * @return {boolean}
+   *   If the object has properties that match the expected structure.
+   */
+  const uiHasExpectedProperties = ui => {
+    if (ui.hasOwnProperty('item') && ui.item !== null) {
+      if (ui.item.hasOwnProperty('value') && ui.item.hasOwnProperty('label')) {
+        return true;
+      }
+    }
+    return false;
+  };
+
+  // Listens to the autocomplete close event.
+  // Triggered when the suggestions are hidden.
+  $(document).on('autocompleteclose', (event, ui) => {
+    // The event target should be the autocomplete text input.
+    if (!$(event.target).hasClass('form-autocomplete')) {
+      return;
+    }
+    if ($.isEmptyObject(ui)) {
+      $('body').addClass('autocompleteclose-event-happened');
+    }
+  });
+
+  // Listens to the autocomplete create event.
+  // Triggered when the autocomplete is created.
+  $(document).on('autocompletecreate', (event, ui) => {
+    // The event target should be the autocomplete text input.
+    if (!$(event.target).hasClass('form-autocomplete')) {
+      return;
+    }
+    if ($.isEmptyObject(ui)) {
+      $('body').addClass('autocompletecreate-event-happened');
+    }
+  });
+
+  // Listens to the autocomplete focus event.
+  // Triggered when focus is moved to an item (not selecting).
+  $(document).on('autocompletefocus', (event, ui) => {
+    // The event target should be the autocomplete text input.
+    if (!$(event.target).hasClass('form-autocomplete')) {
+      return;
+    }
+    if (uiHasExpectedProperties(ui)) {
+      $('body').addClass('autocompletefocus-event-happened');
+    }
+  });
+
+  // Listens to the autocomplete open event.
+  // Triggered when the suggestion menu is opened or updated.
+  $(document).on('autocompleteopen', (event, ui) => {
+    // The event target should be the autocomplete text input.
+    if (!$(event.target).hasClass('form-autocomplete')) {
+      return;
+    }
+    if ($.isEmptyObject(ui)) {
+      $('body').addClass('autocompleteopen-event-happened');
+    }
+  });
+
+  // Listens to the autocomplete response event.
+  // Triggered after a search completes, before the menu is shown.
+  $(document).on('autocompleteresponse', (event, ui) => {
+    // The event target should be the autocomplete text input.
+    if (!$(event.target).hasClass('form-autocomplete')) {
+      return;
+    }
+
+    // The ui variable has a different structure than it does other events.
+    // Typically it is null or represents a single selection. In this case it
+    // is an object containing all suggestions.
+    if (
+      ui.hasOwnProperty('content') &&
+      ui.content.length > 0 &&
+      ui.content[0] !== null &&
+      ui.content[0].hasOwnProperty('value') &&
+      ui.content[0].hasOwnProperty('label')
+    ) {
+      $('body').addClass('autocompleteresponse-event-happened');
+    }
+  });
+
+  // Listens to the autocomplete search event.
+  // Triggered before a search is performed, after minLength and delay are met.
+  $(document).on('autocompletesearch', (event, ui) => {
+    // The event target should be the autocomplete text input.
+    if (!$(event.target).hasClass('form-autocomplete')) {
+      return;
+    }
+    if ($.isEmptyObject(ui)) {
+      $('body').addClass('autocompletesearch-event-happened');
+    }
+  });
+
+  // Listens to the autocomplete search event.
+  // Triggered when an item is selected from the menu.
+  $(document).on('autocompleteselect', (event, ui) => {
+    // The event target should be the autocomplete text input.
+    if (!$(event.target).hasClass('form-autocomplete')) {
+      return;
+    }
+    if (uiHasExpectedProperties(ui)) {
+      $('body').addClass('autocompleteselect-event-happened');
+    }
+  });
+
+  // Listens to the autocomplete change event.
+  // Triggered when the field is blurred, only if the value has changed.
+  $(document).on('autocompletechange', (event, ui) => {
+    // Unlike other listeners in this file, the ui variable is not checked as
+    // its structure can vary depending on what triggers the event. Any
+    // listners to this event would not be able to make assumptions about the
+    // ui variable's structure.
+    // For similar reasons, event.target is not checked either.
+    $('body').addClass('autocompletechange-event-happened');
+  });
+})(jQuery, Drupal);
diff --git a/core/modules/entity_reference/tests/modules/entity_reference_autocomplete_test/js/autocomplete_events.js b/core/modules/entity_reference/tests/modules/entity_reference_autocomplete_test/js/autocomplete_events.js
new file mode 100644
index 0000000000..314789e506
--- /dev/null
+++ b/core/modules/entity_reference/tests/modules/entity_reference_autocomplete_test/js/autocomplete_events.js
@@ -0,0 +1,85 @@
+/**
+* DO NOT EDIT THIS FILE.
+* See the following change record for more information,
+* https://www.drupal.org/node/2815083
+* @preserve
+**/
+
+(function ($, Drupal) {
+  var uiHasExpectedProperties = function uiHasExpectedProperties(ui) {
+    if (ui.hasOwnProperty('item') && ui.item !== null) {
+      if (ui.item.hasOwnProperty('value') && ui.item.hasOwnProperty('label')) {
+        return true;
+      }
+    }
+    return false;
+  };
+
+  $(document).on('autocompleteclose', function (event, ui) {
+    if (!$(event.target).hasClass('form-autocomplete')) {
+      return;
+    }
+    if ($.isEmptyObject(ui)) {
+      $('body').addClass('autocompleteclose-event-happened');
+    }
+  });
+
+  $(document).on('autocompletecreate', function (event, ui) {
+    if (!$(event.target).hasClass('form-autocomplete')) {
+      return;
+    }
+    if ($.isEmptyObject(ui)) {
+      $('body').addClass('autocompletecreate-event-happened');
+    }
+  });
+
+  $(document).on('autocompletefocus', function (event, ui) {
+    if (!$(event.target).hasClass('form-autocomplete')) {
+      return;
+    }
+    if (uiHasExpectedProperties(ui)) {
+      $('body').addClass('autocompletefocus-event-happened');
+    }
+  });
+
+  $(document).on('autocompleteopen', function (event, ui) {
+    if (!$(event.target).hasClass('form-autocomplete')) {
+      return;
+    }
+    if ($.isEmptyObject(ui)) {
+      $('body').addClass('autocompleteopen-event-happened');
+    }
+  });
+
+  $(document).on('autocompleteresponse', function (event, ui) {
+    if (!$(event.target).hasClass('form-autocomplete')) {
+      return;
+    }
+
+    if (ui.hasOwnProperty('content') && ui.content.length > 0 && ui.content[0] !== null && ui.content[0].hasOwnProperty('value') && ui.content[0].hasOwnProperty('label')) {
+      $('body').addClass('autocompleteresponse-event-happened');
+    }
+  });
+
+  $(document).on('autocompletesearch', function (event, ui) {
+    if (!$(event.target).hasClass('form-autocomplete')) {
+      return;
+    }
+    if ($.isEmptyObject(ui)) {
+      $('body').addClass('autocompletesearch-event-happened');
+    }
+  });
+
+  $(document).on('autocompleteselect', function (event, ui) {
+    if (!$(event.target).hasClass('form-autocomplete')) {
+      return;
+    }
+    if (uiHasExpectedProperties(ui)) {
+      $('body').addClass('autocompleteselect-event-happened');
+    }
+  });
+
+  $(document).on('autocompletechange', function (event, ui) {
+    $('body').addClass('autocompletechange-event-happened');
+  });
+})(jQuery, Drupal);
\ No newline at end of file
diff --git a/core/tests/Drupal/FunctionalJavascriptTests/EntityReference/EntityReferenceAutocompleteWidgetTest.php b/core/tests/Drupal/FunctionalJavascriptTests/EntityReference/EntityReferenceAutocompleteWidgetTest.php
index 582c569015..dc50ba9173 100644
--- a/core/tests/Drupal/FunctionalJavascriptTests/EntityReference/EntityReferenceAutocompleteWidgetTest.php
+++ b/core/tests/Drupal/FunctionalJavascriptTests/EntityReference/EntityReferenceAutocompleteWidgetTest.php
@@ -24,7 +24,11 @@ class EntityReferenceAutocompleteWidgetTest extends WebDriverTestBase {
   /**
    * {@inheritdoc}
    */
-  public static $modules = ['node', 'taxonomy'];
+  public static $modules = [
+    'node',
+    'taxonomy',
+    'entity_reference_autocomplete_test',
+  ];
 
   /**
    * The test vocabulary.
@@ -117,39 +121,128 @@ public function testEntityReferenceAutocompleteWidget() {
   }
 
   /**
-   * Test that spaces and commas work properly with autocomplete fields.
+   * Test that selecting terms with spaces and commas work properly.
+   *
+   * @dataProvider providerTestSeparators
    */
-  public function testSeparators() {
+  public function testExistingSeparators($term_to_select) {
     $this->createTagsFieldOnPage();
 
-    $term_commas = 'I,love,commas';
-    $term_spaces = 'Just a fan of spaces';
-    $term_commas_spaces = 'I dig both commas and spaces, apparently';
+    $terms = ['I,love,commas', 'Just a fan of spaces', 'Commas, and spaces'];
+    $terms_not_selected = array_values(array_diff($terms, [$term_to_select]));
 
-    $this->createTerm($this->vocabulary, ['name' => $term_commas]);
-    $this->createTerm($this->vocabulary, ['name' => $term_spaces]);
-    $this->createTerm($this->vocabulary, ['name' => $term_commas_spaces]);
+    $this->createTerm($this->vocabulary, ['name' => $terms[0]]);
+    $this->createTerm($this->vocabulary, ['name' => $terms[1]]);
+    $this->createTerm($this->vocabulary, ['name' => $terms[2]]);
 
     $this->drupalGet('node/add/page');
     $page = $this->getSession()->getPage();
     $assert_session = $this->assertSession();
 
     $autocomplete_field = $assert_session->waitForElement('css', '[name="taxonomy_reference[target_id]"]');
+
     $autocomplete_field->setValue('a');
     $assert_session->waitOnAutocomplete();
 
     $results = $page->findAll('css', '.ui-autocomplete li');
     $this->assertCount(3, $results);
 
-    $assert_session->elementExists('css', '.ui-autocomplete li:contains("' . $term_commas_spaces . '")')->click();
-    $assert_session->pageTextNotContains($term_commas);
-    $assert_session->pageTextNotContains($term_spaces);
+    $assert_session->elementExists('css', '.ui-autocomplete li:contains("' . $term_to_select . '")')->click();
+    $assert_session->pageTextNotContains($terms_not_selected[0]);
+    $assert_session->pageTextNotContains($terms_not_selected[1]);
     $current_value = $autocomplete_field->getValue();
-    $this->assertContains($term_commas_spaces, $current_value);
+    $this->assertContains($term_to_select, $current_value);
+    $page->fillField('Title', 'Just a node in a test');
+    $page->pressButton('Save');
+
+    // The term as it appeared in the autocomplete suggestions should be the
+    // same term on the page.
+    $assert_session->pageTextContains($term_to_select);
   }
 
   /**
-   * Test that markup matches that of jQueryUI autocomplete.
+   * Test that adding terms with spaces and commas work properly.
+   *
+   * @dataProvider providerTestSeparators
+   */
+  public function testAddingSeparators($term_to_add) {
+    $this->createTagsFieldOnPage();
+    $this->drupalGet('node/add/page');
+    $page = $this->getSession()->getPage();
+    $assert_session = $this->assertSession();
+
+    // If the term has a comma, it must be enclosed in quotes.
+    $term_for_input = strpos($term_to_add, ',') !== FALSE ? '"' . $term_to_add . '"' : $term_to_add;
+    $page->fillField('Tags', $term_for_input);
+    $page->fillField('Title', 'Just a node in a test');
+    $page->pressButton('Save');
+
+    // Confirm term was added in its expected formatting.
+    $assert_session->pageTextContains($term_to_add);
+
+    // Confirm term is not wrapped in quotes.
+    $assert_session->pageTextNotContains('"' . $term_to_add . '"');
+  }
+
+  /**
+   * Data provider for testSeparators().
+   */
+  public function providerTestSeparators() {
+    return [
+      ['I,love,commas'],
+      ['Just a fan of spaces'],
+      ['Commas, and spaces'],
+    ];
+  }
+
+  /**
+   * Provides data to self::testSetMethod().
+   */
+  public function providerSetRequestMethod() {
+    return [
+      ['GET'],
+      ['POST'],
+    ];
+  }
+
+  /**
+   * Checks that an autocomplete event has triggered.
+   *
+   * @param string|array $event
+   *   The autocomplete event/events expected to trigger.
+   */
+  protected function assertEventHappened($event) {
+    $assert_session = $this->assertSession();
+    if (is_array($event)) {
+      foreach ($event as $an_event) {
+        $this->assertNotNull($assert_session->waitForElementVisible('css', ".autocomplete$an_event-event-happened"));
+      }
+    }
+    else {
+      $this->assertNotNull($assert_session->waitForElementVisible('css', ".autocomplete$event-event-happened"));
+    }
+  }
+
+  /**
+   * Checks that an autocomplete event has not triggered.
+   *
+   * @param string|array $event
+   *   The autocomplete event/events that should not have triggered.
+   */
+  protected function assertEventNotHappened($event) {
+    $assert_session = $this->assertSession();
+    if (is_array($event)) {
+      foreach ($event as $an_event) {
+        $this->assertNull($assert_session->waitForElementVisible('css', ".autocomplete$an_event-event-happened", 5000));
+      }
+    }
+    else {
+      $this->assertNull($assert_session->waitForElementVisible('css', ".autocomplete$event-event-happened", 5000));
+    }
+  }
+
+  /**
+   * Test that markup and events match that of jQueryUI autocomplete.
    */
   public function testMarkup() {
     $this->createTagsFieldOnPage();
@@ -161,15 +254,19 @@ public function testMarkup() {
     $this->drupalGet('node/add/page');
     $page = $this->getSession()->getPage();
     $assert_session = $this->assertSession();
+    $this->assertNotNull($page->find('css', '.autocompletecreate-event-happened'));
 
-    $autocomplete_field = $assert_session->waitForElement('css', '[name="taxonomy_reference[target_id]"]');
+    $autocomplete_field = $assert_session->elementExists('css', '[name="taxonomy_reference[target_id]"]');
     $this->assertTrue($autocomplete_field->hasClass('form-autocomplete'));
     $this->assertTrue($autocomplete_field->hasClass('ui-autocomplete-input'));
+    $this->assertEventNotHappened(['open', 'response', 'search']);
+
     $autocomplete_field->setValue('a');
     $assert_session->waitOnAutocomplete();
-    $this->assertNull($page->find('css', '.ui-state-active'));
-    $suggestion_list = $page->find('css', 'body > .ui-autocomplete');
+    $this->assertEventHappened(['open', 'response', 'search']);
 
+    $this->assertNull($page->find('css', '.ui-state-active'));
+    $suggestion_list = $page->find('css', '.ui-autocomplete');
     foreach (['ui-menu', 'ui-widget', 'ui-widget-content', 'ui-front'] as $class) {
       $this->assertTrue($suggestion_list->hasClass($class));
     }
@@ -183,11 +280,27 @@ public function testMarkup() {
       $this->assertEqual($link->getAttribute('tabindex'), '-1');
     }
 
-    // Arrow down to the first suggestion and confirm the ui-state-active
-    // class is added.
+    $this->assertEventNotHappened('focus');
+    // Arrow down to the first suggestion.
     $autocomplete_field->keyDown($autocomplete_field->getXpath(), 40);
     $active_selection = $page->find('css', '.ui-menu-item .ui-state-active');
     $this->assertNotNull($active_selection);
+    $this->assertEventHappened('focus');
+    $this->assertEventNotHappened(['select', 'close']);
+
+    $active_selection->click();
+
+    // Wait for suggestions to become hidden -- cant use
+    // JSWebAssert::assertNoElementAfterWait() because the suggestions are
+    // still part of the DOM, just hidden.
+    $condition = "jQuery('.ui-autocomplete:visible').length === 0";
+    $this->assertJsCondition($condition);
+    $this->assertEventHappened(['select', 'close']);
+
+    // The change event only happens when the autocomplete input is blurred.
+    $this->assertEventNotHappened('change');
+    $assert_session->elementExists('css', '[name="title[0][value]"]')->setValue('FORCING A BLUR OF THE AUTOCOMPLETE FIELD');
+    $this->assertEventHappened('change');
   }
 
   /**