Issue #1379070 by ocsilalala, rkjha, swentel, kid_icarus, Gisle: Field with...

Issue #1379070 by ocsilalala, rkjha, swentel, kid_icarus, Gisle: Field with multiple select list does not allow -None- to be a default value.

core/includes/form.inc

@@ -858,6 +858,8 @@ function form_select_options($element, $choices = NULL) {
   // isset() fails in this situation.
   $value_valid = isset($element['#value']) || array_key_exists('#value', $element);
   $value_is_array = $value_valid && is_array($element['#value']);
+  // Check if the element is multiple select and no value has been selected.
+  $empty_value = (empty($element['#value']) && !empty($element['#multiple']));
   $options = '';
   foreach ($choices as $key => $choice) {
     if (is_array($choice)) {
@@ -870,7 +872,8 @@ function form_select_options($element, $choices = NULL) {
     }
     else {
       $key = (string) $key;
-      if ($value_valid && (!$value_is_array && (string) $element['#value'] === $key || ($value_is_array && in_array($key, $element['#value'])))) {
+      $empty_choice = $empty_value && $key == '_none';
+      if ($value_valid && ((!$value_is_array && (string) $element['#value'] === $key || ($value_is_array && in_array($key, $element['#value']))) || $empty_choice)) {
         $selected = ' selected="selected"';
       }
       else {

core/modules/options/lib/Drupal/options/Tests/OptionsWidgetsTest.php

@@ -378,6 +378,7 @@ function testSelectListMultiple() {
 
     // Display form: with no field data, nothing is selected.
     $this->drupalGet('entity_test/manage/' . $entity->id());
+    $this->assertOptionSelected("edit-card-2", '_none');
     $this->assertNoOptionSelected('edit-card-2', 0);
     $this->assertNoOptionSelected('edit-card-2', 1);
     $this->assertNoOptionSelected('edit-card-2', 2);

core/modules/taxonomy/lib/Drupal/taxonomy/Tests/TermFieldMultipleVocabularyTest.php

@@ -87,7 +87,9 @@ function testTaxonomyTermFieldMultipleVocabularies() {
 
     // Submit an entity with both terms.
     $this->drupalGet('entity_test/add');
-    $this->assertFieldByName("{$this->field_name}[]", '', 'Widget is displayed.');
+    // Just check if the widget for the select is displayed, the NULL value is
+    // used to ignore the value check.
+    $this->assertFieldByName("{$this->field_name}[]", NULL, 'Widget is displayed.');
     $edit = array(
       'user_id' => mt_rand(0, 10),
       'name' => $this->randomName(),
@@ -125,7 +127,9 @@ function testTaxonomyTermFieldMultipleVocabularies() {
 
     // The widget should still be displayed.
     $this->drupalGet('entity_test/add');
-    $this->assertFieldByName("{$this->field_name}[]", '', 'Widget is still displayed.');
+    // Just check if the widget for the select is displayed, the NULL value is
+    // used to ignore the value check.
+    $this->assertFieldByName("{$this->field_name}[]", NULL, 'Widget is still displayed.');
 
     // Term 1 should still pass validation.
     $edit = array(