diff --git a/core/modules/datetime/config/schema/datetime.schema.yml b/core/modules/datetime/config/schema/datetime.schema.yml
index e627ce0..200751a 100644
--- a/core/modules/datetime/config/schema/datetime.schema.yml
+++ b/core/modules/datetime/config/schema/datetime.schema.yml
@@ -104,12 +104,18 @@ field.value.daterange:
   type: mapping
   label: 'Default value'
   mapping:
-    default_date_type:
+    default_start_date_type:
       type: string
-      label: 'Default date type'
-    default_date:
+      label: 'Default start date type'
+    default_start_date:
       type: string
-      label: 'Default date value'
+      label: 'Default start date value'
+    default_end_date_type:
+      type: string
+      label: 'Default end date type'
+    default_end_date:
+      type: string
+      label: 'Default end date value'
 
 field.formatter.settings.daterange_base:
   type: mapping
diff --git a/core/modules/datetime/src/Plugin/Field/FieldType/DateRangeFieldItemList.php b/core/modules/datetime/src/Plugin/Field/FieldType/DateRangeFieldItemList.php
index 2c1409d..d6dbf7d 100644
--- a/core/modules/datetime/src/Plugin/Field/FieldType/DateRangeFieldItemList.php
+++ b/core/modules/datetime/src/Plugin/Field/FieldType/DateRangeFieldItemList.php
@@ -32,25 +32,47 @@ public function defaultValuesForm(array &$form, FormStateInterface $form_state)
 
       $element = [
         '#parents' => ['default_value_input'],
-        'default_date_type' => [
+        'default_start_date_type' => [
           '#type' => 'select',
-          '#title' => t('Default dates'),
-          '#description' => t('Set a default value for these dates.'),
-          '#default_value' => isset($default_value[0]['default_date_type']) ? $default_value[0]['default_date_type'] : '',
+          '#title' => $this->t('Default start date'),
+          '#description' => $this->t('Set a default value for the start date.'),
+          '#default_value' => isset($default_value[0]['default_start_date_type']) ? $default_value[0]['default_start_date_type'] : '',
           '#options' => [
-            static::DEFAULT_VALUE_NOW => t('Current date'),
-            static::DEFAULT_VALUE_CUSTOM => t('Relative date'),
+            static::DEFAULT_VALUE_NOW => $this->t('Current date'),
+            static::DEFAULT_VALUE_CUSTOM => $this->t('Relative date'),
           ],
           '#empty_value' => '',
         ],
-        'default_date' => [
+        'default_start_date' => [
           '#type' => 'textfield',
-          '#title' => t('Relative default value'),
-          '#description' => t("Describe a time by reference to the current day, like '+90 days' (90 days from the day the field is created) or '+1 Saturday' (the next Saturday). See <a href=\"http://php.net/manual/function.strtotime.php\">strtotime</a> for more details."),
-          '#default_value' => (isset($default_value[0]['default_date_type']) && $default_value[0]['default_date_type'] == static::DEFAULT_VALUE_CUSTOM) ? $default_value[0]['default_date'] : '',
+          '#title' => $this->t('Relative default value'),
+          '#description' => $this->t("Describe a time by reference to the current day, like '+90 days' (90 days from the day the field is created) or '+1 Saturday' (the next Saturday). See <a href=\"http://php.net/manual/function.strtotime.php\">strtotime</a> for more details."),
+          '#default_value' => (isset($default_value[0]['default_start_date_type']) && $default_value[0]['default_start_date_type'] == static::DEFAULT_VALUE_CUSTOM) ? $default_value[0]['default_start_date'] : '',
           '#states' => [
             'visible' => [
-              ':input[id="edit-default-value-input-default-date-type"]' => ['value' => static::DEFAULT_VALUE_CUSTOM],
+              ':input[id="edit-default-value-input-default-start-date-type"]' => ['value' => static::DEFAULT_VALUE_CUSTOM],
+            ],
+          ],
+        ],
+        'default_end_date_type' => [
+          '#type' => 'select',
+          '#title' => $this->t('Default end date'),
+          '#description' => $this->t('Set a default value for the end date.'),
+          '#default_value' => isset($default_value[0]['default_end_date_type']) ? $default_value[0]['default_end_date_type'] : '',
+          '#options' => [
+            static::DEFAULT_VALUE_NOW => $this->t('Current date'),
+            static::DEFAULT_VALUE_CUSTOM => $this->t('Relative date'),
+          ],
+          '#empty_value' => '',
+        ],
+        'default_end_date' => [
+          '#type' => 'textfield',
+          '#title' => $this->t('Relative default value'),
+          '#description' => $this->t("Describe a time by reference to the current day, like '+90 days' (90 days from the day the field is created) or '+1 Saturday' (the next Saturday). See <a href=\"http://php.net/manual/function.strtotime.php\">strtotime</a> for more details."),
+          '#default_value' => (isset($default_value[0]['default_end_date_type']) && $default_value[0]['default_end_date_type'] == static::DEFAULT_VALUE_CUSTOM) ? $default_value[0]['default_end_date'] : '',
+          '#states' => [
+            'visible' => [
+              ':input[id="edit-default-value-input-default-end-date-type"]' => ['value' => static::DEFAULT_VALUE_CUSTOM],
             ],
           ],
         ],
@@ -64,10 +86,17 @@ public function defaultValuesForm(array &$form, FormStateInterface $form_state)
    * {@inheritdoc}
    */
   public function defaultValuesFormValidate(array $element, array &$form, FormStateInterface $form_state) {
-    if ($form_state->getValue(['default_value_input', 'default_date_type']) == static::DEFAULT_VALUE_CUSTOM) {
-      $is_strtotime = @strtotime($form_state->getValue(['default_value_input', 'default_date']));
+    if ($form_state->getValue(['default_value_input', 'default_start_date_type']) == static::DEFAULT_VALUE_CUSTOM) {
+      $is_strtotime = @strtotime($form_state->getValue(['default_value_input', 'default_start_date']));
+      if (!$is_strtotime) {
+        $form_state->setErrorByName('default_value_input][default_start_date', $this->t('The relative start date value entered is invalid.'));
+      }
+    }
+
+    if ($form_state->getValue(['default_value_input', 'default_end_date_type']) == static::DEFAULT_VALUE_CUSTOM) {
+      $is_strtotime = @strtotime($form_state->getValue(['default_value_input', 'default_end_date']));
       if (!$is_strtotime) {
-        $form_state->setErrorByName('default_value_input][default_date', t('The relative date value entered is invalid.'));
+        $form_state->setErrorByName('default_value_input][default_end_date', $this->t('The relative end date value entered is invalid.'));
       }
     }
   }
@@ -76,9 +105,12 @@ public function defaultValuesFormValidate(array $element, array &$form, FormStat
    * {@inheritdoc}
    */
   public function defaultValuesFormSubmit(array $element, array &$form, FormStateInterface $form_state) {
-    if ($form_state->getValue(['default_value_input', 'default_date_type'])) {
-      if ($form_state->getValue(['default_value_input', 'default_date_type']) == static::DEFAULT_VALUE_NOW) {
-        $form_state->setValueForElement($element['default_date'], static::DEFAULT_VALUE_NOW);
+    if ($form_state->getValue(['default_value_input', 'default_start_date_type']) && $form_state->getValue(['default_value_input', 'default_end_date_type'])) {
+      if ($form_state->getValue(['default_value_input', 'default_start_date_type']) == static::DEFAULT_VALUE_NOW) {
+        $form_state->setValueForElement($element['default_start_date'], static::DEFAULT_VALUE_NOW);
+      }
+      if ($form_state->getValue(['default_value_input', 'default_end_date_type']) == static::DEFAULT_VALUE_NOW) {
+        $form_state->setValueForElement($element['default_end_date'], static::DEFAULT_VALUE_NOW);
       }
       return [$form_state->getValue('default_value_input')];
     }
@@ -91,21 +123,23 @@ public function defaultValuesFormSubmit(array $element, array &$form, FormStateI
   public static function processDefaultValue($default_value, FieldableEntityInterface $entity, FieldDefinitionInterface $definition) {
     $default_value = parent::processDefaultValue($default_value, $entity, $definition);
 
-    if (isset($default_value[0]['default_date_type'])) {
+    if (isset($default_value[0]['default_start_date_type']) && isset($default_value[0]['default_end_date_type'])) {
       // A default value should be in the format and timezone used for date
       // storage. All-day ranges are stored the same as date+time ranges.
-      $date = new DrupalDateTime($default_value[0]['default_date'], DATETIME_STORAGE_TIMEZONE);
       $storage_format = $definition->getSetting('daterange_type') == DateRangeItem::DATERANGE_TYPE_DATE ? DATETIME_DATE_STORAGE_FORMAT : DATETIME_DATETIME_STORAGE_FORMAT;
-      $value = $date->format($storage_format);
+      $start_date = new DrupalDateTime($default_value[0]['default_start_date'], DATETIME_STORAGE_TIMEZONE);
+      $start_value = $start_date->format($storage_format);
+      $end_date = new DrupalDateTime($default_value[0]['default_end_date'], DATETIME_STORAGE_TIMEZONE);
+      $end_value = $end_date->format($storage_format);
       // We only provide a default value for the first item, as do all fields.
       // Otherwise, there is no way to clear out unwanted values on multiple
       // value fields.
       $default_value = [
         [
-          'value' => $value,
-          'start_date' => $date,
-          'value2' => $value,
-          'end_date' => $date,
+          'value' => $start_value,
+          'start_date' => $start_date,
+          'value2' => $end_value,
+          'end_date' => $end_date,
         ],
       ];
     }
diff --git a/core/modules/datetime/src/Tests/DateRangeFieldTest.php b/core/modules/datetime/src/Tests/DateRangeFieldTest.php
index 5ef4c71..8266183 100644
--- a/core/modules/datetime/src/Tests/DateRangeFieldTest.php
+++ b/core/modules/datetime/src/Tests/DateRangeFieldTest.php
@@ -6,6 +6,8 @@
 use Drupal\Component\Utility\Unicode;
 use Drupal\Core\Datetime\DrupalDateTime;
 use Drupal\Core\Entity\Entity\EntityViewDisplay;
+use Drupal\datetime\Plugin\Field\FieldType\DateRangeItem;
+use Drupal\entity_test\Entity\EntityTest;
 use Drupal\field\Entity\FieldConfig;
 use Drupal\field\Entity\FieldStorageConfig;
 use Drupal\node\Entity\Node;
@@ -75,12 +77,12 @@ protected function setUp() {
 
     // Create a field with settings to validate.
     $field_name = Unicode::strtolower($this->randomMachineName());
-    $this->fieldStorage = FieldStorageConfig::create(array(
+    $this->fieldStorage = FieldStorageConfig::create([
       'field_name' => $field_name,
       'entity_type' => 'entity_test',
       'type' => 'daterange',
-      'settings' => array('daterange_type' => 'date'),
-    ));
+      'settings' => array('daterange_type' => DateRangeItem::DATERANGE_TYPE_DATE),
+    ]);
     $this->fieldStorage->save();
     $this->field = FieldConfig::create([
       'field_storage' => $this->fieldStorage,
@@ -95,16 +97,16 @@ protected function setUp() {
       ))
       ->save();
 
-    $this->defaultSettings = array(
+    $this->defaultSettings = [
       'separator' => '-',
       'timezone_override' => '',
-    );
+    ];
 
-    $this->displayOptions = array(
+    $this->displayOptions = [
       'type' => 'daterange_default',
       'label' => 'hidden',
       'settings' => array('format_type' => 'medium') + $this->defaultSettings,
-    );
+    ];
     entity_get_display($this->field->getTargetEntityTypeId(), $this->field->getTargetBundle(), 'full')
       ->setComponent($field_name, $this->displayOptions)
       ->save();
@@ -125,6 +127,13 @@ function testDatetimeRangeField() {
   }
 
   /**
+   * Tests all-day field.
+   */
+  function testAlldayRangeField() {
+    $this->fail('Write a real test.');
+  }
+
+  /**
    * Tests Date Range List Widget functionality.
    */
   function testDatelistWidget() {
@@ -135,21 +144,383 @@ function testDatelistWidget() {
    * Test default value functionality.
    */
   function testDefaultValue() {
-    $this->fail('Write a real test.');
+    // Create a test content type.
+    $this->drupalCreateContentType(['type' => 'date_content']);
+
+    // Create a field storage with settings to validate.
+    $field_name = Unicode::strtolower($this->randomMachineName());
+    $field_storage = FieldStorageConfig::create([
+      'field_name' => $field_name,
+      'entity_type' => 'node',
+      'type' => 'daterange',
+      'settings' => ['daterange_type' => DateRangeItem::DATERANGE_TYPE_DATE],
+    ]);
+    $field_storage->save();
+
+    $field = FieldConfig::create([
+      'field_storage' => $field_storage,
+      'bundle' => 'date_content',
+    ]);
+    $field->save();
+
+    // Set now as default_value.
+    $field_edit = [
+      'default_value_input[default_start_date_type]' => 'now',
+      'default_value_input[default_end_date_type]' => 'now',
+    ];
+    $this->drupalPostForm('admin/structure/types/manage/date_content/fields/node.date_content.' . $field_name, $field_edit, t('Save settings'));
+
+    // Check that default value is selected in default value form.
+    $this->drupalGet('admin/structure/types/manage/date_content/fields/node.date_content.' . $field_name);
+    $this->assertOptionSelected('edit-default-value-input-default-start-date-type', 'now', 'The default start value is selected in instance settings page');
+    $this->assertFieldByName('default_value_input[default_start_date]', '', 'The relative start default value is empty in instance settings page');
+    $this->assertOptionSelected('edit-default-value-input-default-end-date-type', 'now', 'The default end value is selected in instance settings page');
+    $this->assertFieldByName('default_value_input[default_end_date]', '', 'The relative end default value is empty in instance settings page');
+
+    // Check if default_date has been stored successfully.
+    $config_entity = $this->config('field.field.node.date_content.' . $field_name)->get();
+    $this->assertEqual($config_entity['default_value'][0], [
+      'default_start_date_type' => 'now',
+      'default_start_date' => 'now',
+      'default_end_date_type' => 'now',
+      'default_end_date' => 'now'
+    ], 'Default value has been stored successfully');
+
+    // Clear field cache in order to avoid stale cache values.
+    \Drupal::entityManager()->clearCachedFieldDefinitions();
+
+    // Create a new node to check that datetime field default value is today.
+    $new_node = Node::create(['type' => 'date_content']);
+    $expected_date = new DrupalDateTime('now', DATETIME_STORAGE_TIMEZONE);
+    $this->assertEqual($new_node->get($field_name)->offsetGet(0)->value, $expected_date->format(DATETIME_DATE_STORAGE_FORMAT));
+    $this->assertEqual($new_node->get($field_name)->offsetGet(0)->value2, $expected_date->format(DATETIME_DATE_STORAGE_FORMAT));
+
+    // Set an invalid relative default_value to test validation.
+    $field_edit = [
+      'default_value_input[default_start_date_type]' => 'relative',
+      'default_value_input[default_start_date]' => 'invalid date',
+      'default_value_input[default_end_date_type]' => 'relative',
+      'default_value_input[default_end_date]' => '+1 day',
+    ];
+    $this->drupalPostForm('admin/structure/types/manage/date_content/fields/node.date_content.' . $field_name, $field_edit, t('Save settings'));
+    $this->assertText('The relative start date value entered is invalid.');
+
+    $field_edit = [
+      'default_value_input[default_start_date_type]' => 'relative',
+      'default_value_input[default_start_date]' => '+1 day',
+      'default_value_input[default_end_date_type]' => 'relative',
+      'default_value_input[default_end_date]' => 'invalid date',
+    ];
+    $this->drupalPostForm('admin/structure/types/manage/date_content/fields/node.date_content.' . $field_name, $field_edit, t('Save settings'));
+    $this->assertText('The relative end date value entered is invalid.');
+
+    // Set a relative default_value.
+    $field_edit = [
+      'default_value_input[default_start_date_type]' => 'relative',
+      'default_value_input[default_start_date]' => '+45 days',
+      'default_value_input[default_end_date_type]' => 'relative',
+      'default_value_input[default_end_date]' => '+90 days',
+    ];
+    $this->drupalPostForm('admin/structure/types/manage/date_content/fields/node.date_content.' . $field_name, $field_edit, t('Save settings'));
+
+    // Check that default value is selected in default value form.
+    $this->drupalGet('admin/structure/types/manage/date_content/fields/node.date_content.' . $field_name);
+    $this->assertOptionSelected('edit-default-value-input-default-start-date-type', 'relative', 'The default start value is selected in instance settings page');
+    $this->assertFieldByName('default_value_input[default_start_date]', '+45 days', 'The relative default start value is displayed in instance settings page');
+    $this->assertOptionSelected('edit-default-value-input-default-end-date-type', 'relative', 'The default end value is selected in instance settings page');
+    $this->assertFieldByName('default_value_input[default_end_date]', '+90 days', 'The relative default end value is displayed in instance settings page');
+
+    // Check if default_date has been stored successfully.
+    $config_entity = $this->config('field.field.node.date_content.' . $field_name)->get();
+    $this->assertEqual($config_entity['default_value'][0], [
+      'default_start_date_type' => 'relative',
+      'default_start_date' => '+45 days',
+      'default_end_date_type' => 'relative',
+      'default_end_date' => '+90 days',
+    ], 'Default value has been stored successfully');
+
+    // Clear field cache in order to avoid stale cache values.
+    \Drupal::entityManager()->clearCachedFieldDefinitions();
+
+    // Create a new node to check that datetime field default value is +90 days.
+    $new_node = Node::create(['type' => 'date_content']);
+    $expected_start_date = new DrupalDateTime('+45 days', DATETIME_STORAGE_TIMEZONE);
+    $expected_end_date = new DrupalDateTime('+90 days', DATETIME_STORAGE_TIMEZONE);
+    $this->assertEqual($new_node->get($field_name)->offsetGet(0)->value, $expected_start_date->format(DATETIME_DATE_STORAGE_FORMAT));
+    $this->assertEqual($new_node->get($field_name)->offsetGet(0)->value2, $expected_end_date->format(DATETIME_DATE_STORAGE_FORMAT));
+
+    // Remove default value.
+    $field_edit = [
+      'default_value_input[default_start_date_type]' => '',
+      'default_value_input[default_end_date_type]' => '',
+    ];
+    $this->drupalPostForm('admin/structure/types/manage/date_content/fields/node.date_content.' . $field_name, $field_edit, t('Save settings'));
+
+    // Check that default value is selected in default value form.
+    $this->drupalGet('admin/structure/types/manage/date_content/fields/node.date_content.' . $field_name);
+    $this->assertOptionSelected('edit-default-value-input-default-start-date-type', '', 'The default start value is selected in instance settings page');
+    $this->assertFieldByName('default_value_input[default_start_date]', '', 'The relative default start value is empty in instance settings page');
+    $this->assertOptionSelected('edit-default-value-input-default-end-date-type', '', 'The default end value is selected in instance settings page');
+    $this->assertFieldByName('default_value_input[default_end_date]', '', 'The relative default end value is empty in instance settings page');
+
+    // Check if default_date has been stored successfully.
+    $config_entity = $this->config('field.field.node.date_content.' . $field_name)->get();
+    $this->assertTrue(empty($config_entity['default_value']), 'Empty default value has been stored successfully');
+
+    // Clear field cache in order to avoid stale cache values.
+    \Drupal::entityManager()->clearCachedFieldDefinitions();
+
+    // Create a new node to check that datetime field default value is not set.
+    $new_node = Node::create(['type' => 'date_content']);
+    $this->assertNull($new_node->get($field_name)->value, 'Default value is not set');
   }
 
   /**
    * Test that invalid values are caught and marked as invalid.
    */
   function testInvalidField() {
-    $this->fail('Write a real test.');
+    // Change the field to a datetime field.
+    $this->fieldStorage->setSetting('daterange_type', DateRangeItem::DATERANGE_TYPE_DATETIME);
+    $this->fieldStorage->save();
+    $field_name = $this->fieldStorage->getName();
+
+    // Display creation form.
+    $this->drupalGet('entity_test/add');
+    $this->assertFieldByName("{$field_name}[0][value][date]", '', 'Start date element found.');
+    $this->assertFieldByName("{$field_name}[0][value][time]", '', 'Start time element found.');
+    $this->assertFieldByName("{$field_name}[0][value2][date]", '', 'End date element found.');
+    $this->assertFieldByName("{$field_name}[0][value2][time]", '', 'End time element found.');
+
+    // Submit invalid start dates and ensure they is not accepted.
+    $date_value = '';
+    $edit = [
+      "{$field_name}[0][value][date]" => $date_value,
+      "{$field_name}[0][value][time]" => '12:00:00',
+      "{$field_name}[0][value2][date]" => '2012-12-01',
+      "{$field_name}[0][value2][time]" => '12:00:00',
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertText('date is invalid', 'Empty start date value has been caught.');
+
+    $date_value = 'aaaa-12-01';
+    $edit = [
+      "{$field_name}[0][value][date]" => $date_value,
+      "{$field_name}[0][value][time]" => '00:00:00',
+      "{$field_name}[0][value2][date]" => '2012-12-01',
+      "{$field_name}[0][value2][time]" => '12:00:00',
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertText('date is invalid', format_string('Invalid start year value %date has been caught.', ['%date' => $date_value]));
+
+    $date_value = '2012-75-01';
+    $edit = [
+      "{$field_name}[0][value][date]" => $date_value,
+      "{$field_name}[0][value][time]" => '00:00:00',
+      "{$field_name}[0][value2][date]" => '2012-12-01',
+      "{$field_name}[0][value2][time]" => '12:00:00',
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertText('date is invalid', format_string('Invalid start month value %date has been caught.', ['%date' => $date_value]));
+
+    $date_value = '2012-12-99';
+    $edit = [
+      "{$field_name}[0][value][date]" => $date_value,
+      "{$field_name}[0][value][time]" => '00:00:00',
+      "{$field_name}[0][value2][date]" => '2012-12-01',
+      "{$field_name}[0][value2][time]" => '12:00:00',
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertText('date is invalid', format_string('Invalid start day value %date has been caught.', ['%date' => $date_value]));
+
+    // Submit invalid start times and ensure they is not accepted.
+    $time_value = '';
+    $edit = [
+      "{$field_name}[0][value][date]" => '2012-12-01',
+      "{$field_name}[0][value][time]" => $time_value,
+      "{$field_name}[0][value2][date]" => '2012-12-01',
+      "{$field_name}[0][value2][time]" => '12:00:00',
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertText('date is invalid', 'Empty start time value has been caught.');
+
+    $time_value = '49:00:00';
+    $edit = [
+      "{$field_name}[0][value][date]" => '2012-12-01',
+      "{$field_name}[0][value][time]" => $time_value,
+      "{$field_name}[0][value2][date]" => '2012-12-01',
+      "{$field_name}[0][value2][time]" => '12:00:00',
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertText('date is invalid', format_string('Invalid start hour value %time has been caught.', ['%time' => $time_value]));
+
+    $time_value = '12:99:00';
+    $edit = [
+      "{$field_name}[0][value][date]" => '2012-12-01',
+      "{$field_name}[0][value][time]" => $time_value,
+      "{$field_name}[0][value2][date]" => '2012-12-01',
+      "{$field_name}[0][value2][time]" => '12:00:00',
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertText('date is invalid', format_string('Invalid start minute value %time has been caught.', ['%time' => $time_value]));
+
+    $time_value = '12:15:99';
+    $edit = [
+      "{$field_name}[0][value][date]" => '2012-12-01',
+      "{$field_name}[0][value][time]" => $time_value,
+      "{$field_name}[0][value2][date]" => '2012-12-01',
+      "{$field_name}[0][value2][time]" => '12:00:00',
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertText('date is invalid', format_string('Invalid start second value %time has been caught.', ['%time' => $time_value]));
+
+    // Submit invalid end dates and ensure they is not accepted.
+    $date_value = '';
+    $edit = [
+      "{$field_name}[0][value][date]" => '2012-12-01',
+      "{$field_name}[0][value][time]" => '12:00:00',
+      "{$field_name}[0][value2][date]" => $date_value,
+      "{$field_name}[0][value2][time]" => '12:00:00',
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertText('date is invalid', 'Empty end date value has been caught.');
+
+    $date_value = 'aaaa-12-01';
+    $edit = [
+      "{$field_name}[0][value][date]" => '2012-12-01',
+      "{$field_name}[0][value][time]" => '12:00:00',
+      "{$field_name}[0][value2][date]" => $date_value,
+      "{$field_name}[0][value2][time]" => '00:00:00',
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertText('date is invalid', format_string('Invalid end year value %date has been caught.', ['%date' => $date_value]));
+
+    $date_value = '2012-75-01';
+    $edit = [
+      "{$field_name}[0][value][date]" => '2012-12-01',
+      "{$field_name}[0][value][time]" => '12:00:00',
+      "{$field_name}[0][value2][date]" => $date_value,
+      "{$field_name}[0][value2][time]" => '00:00:00',
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertText('date is invalid', format_string('Invalid end month value %date has been caught.', ['%date' => $date_value]));
+
+    $date_value = '2012-12-99';
+    $edit = [
+      "{$field_name}[0][value][date]" => '2012-12-01',
+      "{$field_name}[0][value][time]" => '12:00:00',
+      "{$field_name}[0][value2][date]" => $date_value,
+      "{$field_name}[0][value2][time]" => '00:00:00',
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertText('date is invalid', format_string('Invalid end day value %date has been caught.', ['%date' => $date_value]));
+
+    // Submit invalid start times and ensure they is not accepted.
+    $time_value = '';
+    $edit = [
+      "{$field_name}[0][value][date]" => '2012-12-01',
+      "{$field_name}[0][value][time]" => '12:00:00',
+      "{$field_name}[0][value2][date]" => '2012-12-01',
+      "{$field_name}[0][value2][time]" => $time_value,
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertText('date is invalid', 'Empty end time value has been caught.');
+
+    $time_value = '49:00:00';
+    $edit = [
+      "{$field_name}[0][value][date]" => '2012-12-01',
+      "{$field_name}[0][value][time]" => '12:00:00',
+      "{$field_name}[0][value2][date]" => '2012-12-01',
+      "{$field_name}[0][value2][time]" => $time_value,
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertText('date is invalid', format_string('Invalid end hour value %time has been caught.', ['%time' => $time_value]));
+
+    $time_value = '12:99:00';
+    $edit = [
+      "{$field_name}[0][value][date]" => '2012-12-01',
+      "{$field_name}[0][value][time]" => '12:00:00',
+      "{$field_name}[0][value2][date]" => '2012-12-01',
+      "{$field_name}[0][value2][time]" => $time_value,
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertText('date is invalid', format_string('Invalid end minute value %time has been caught.', ['%time' => $time_value]));
+
+    $time_value = '12:15:99';
+    $edit = [
+      "{$field_name}[0][value][date]" => '2012-12-01',
+      "{$field_name}[0][value][time]" => '12:00:00',
+      "{$field_name}[0][value2][date]" => '2012-12-01',
+      "{$field_name}[0][value2][time]" => $time_value,
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertText('date is invalid', format_string('Invalid end second value %time has been caught.', ['%time' => $time_value]));
   }
 
   /**
    * Tests that 'Date' field storage setting form is disabled if field has data.
    */
   public function testDateStorageSettings() {
-    $this->fail('Write a real test.');
+    // Create a test content type.
+    $this->drupalCreateContentType(['type' => 'date_content']);
+
+    // Create a field storage with settings to validate.
+    $field_name = Unicode::strtolower($this->randomMachineName());
+    $field_storage = FieldStorageConfig::create([
+      'field_name' => $field_name,
+      'entity_type' => 'node',
+      'type' => 'daterange',
+      'settings' => [
+        'daterange_type' => DateRangeItem::DATERANGE_TYPE_DATE,
+      ],
+    ]);
+    $field_storage->save();
+    $field = FieldConfig::create([
+      'field_storage' => $field_storage,
+      'field_name' => $field_name,
+      'bundle' => 'date_content',
+    ]);
+    $field->save();
+
+    entity_get_form_display('node', 'date_content', 'default')
+      ->setComponent($field_name, [
+        'type' => 'datetime_default',
+      ])
+      ->save();
+    $edit = [
+      'title[0][value]' => $this->randomString(),
+      'body[0][value]' => $this->randomString(),
+      $field_name . '[0][value][date]' => '2016-04-01',
+      $field_name . '[0][value2][date]' => '2016-04-02',
+    ];
+    $this->drupalPostForm('node/add/date_content', $edit, t('Save'));
+    $this->drupalGet('admin/structure/types/manage/date_content/fields/node.date_content.' . $field_name . '/storage');
+    $result = $this->xpath("//*[@id='edit-settings-daterange-type' and contains(@disabled, 'disabled')]");
+    $this->assertEqual(count($result), 1, "Changing daterange setting is disabled.");
+    $this->assertText('There is data for this field in the database. The field settings can no longer be changed.');
+  }
+
+
+  /**
+   * Renders a entity_test and sets the output in the internal browser.
+   *
+   * @param int $id
+   *   The entity_test ID to render.
+   * @param string $view_mode
+   *   (optional) The view mode to use for rendering. Defaults to 'full'.
+   * @param bool $reset
+   *   (optional) Whether to reset the entity_test controller cache. Defaults to
+   *   TRUE to simplify testing.
+   */
+  protected function renderTestEntity($id, $view_mode = 'full', $reset = TRUE) {
+    if ($reset) {
+      \Drupal::service('entity_type.manager')->getStorage('entity_test')->resetCache([$id]);
+    }
+    $entity = EntityTest::load($id);
+    $display = EntityViewDisplay::collectRenderDisplay($entity, $view_mode);
+    $build = $display->build($entity);
+    $output = \Drupal::service('renderer')->renderRoot($build);
+    $this->setRawContent($output);
+    $this->verbose($output);
   }
 
 }