Merge pull request magento#3120 from magento-chaika/chaika_sept_22

Fixed issues:
- MAGETWO-93939 Cannot clear Date of Birth value in customer edit page in Admin

Author: Yevhen Miroshnychenko

app/code/Magento/Customer/Model/Metadata/Form/Date.php

@@ -12,7 +12,7 @@
 class Date extends AbstractData
 {
     /**
-     * {@inheritdoc}
+     * @inheritdoc
      */
     public function extractValue(\Magento\Framework\App\RequestInterface $request)
     {
@@ -21,7 +21,7 @@ public function extractValue(\Magento\Framework\App\RequestInterface $request)
     }
 
     /**
-     * {@inheritdoc}
+     * @inheritdoc
      * @SuppressWarnings(PHPMD.CyclomaticComplexity)
      * @SuppressWarnings(PHPMD.NPathComplexity)
      */
@@ -95,29 +95,23 @@ public function validateValue($value)
     }
 
     /**
-     * {@inheritdoc}
+     * @inheritdoc
      */
     public function compactValue($value)
     {
-        if ($value !== false) {
-            if (empty($value)) {
-                $value = null;
-            }
-            return $value;
-        }
-        return false;
+        return $value;
     }
 
     /**
-     * {@inheritdoc}
+     * @inheritdoc
      */
     public function restoreValue($value)
     {
         return $this->compactValue($value);
     }
 
     /**
-     * {@inheritdoc}
+     * @inheritdoc
      */
     public function outputValue($format = \Magento\Customer\Model\Metadata\ElementFactory::OUTPUT_FORMAT_TEXT)
     {

app/code/Magento/Customer/Test/Unit/Model/Metadata/Form/DateTest.php

@@ -12,6 +12,9 @@ class DateTest extends AbstractFormTestCase
     /** @var \Magento\Customer\Model\Metadata\Form\Date */
     protected $date;
 
+    /**
+     * @inheritdoc
+     */
     protected function setUp()
     {
         parent::setUp();
@@ -46,6 +49,9 @@ protected function setUp()
         );
     }
 
+    /**
+     * Test extractValue
+     */
     public function testExtractValue()
     {
         $requestMock = $this->getMockBuilder(\Magento\Framework\App\RequestInterface::class)
@@ -174,7 +180,7 @@ public function compactAndRestoreValueDataProvider()
         return [
             [1, 1],
             [false, false],
-            ['', null],
+            [null, null],
             ['test', 'test'],
             [['element1', 'element2'], ['element1', 'element2']]
         ];
@@ -191,6 +197,9 @@ public function testRestoreValue($value, $expected)
         $this->assertSame($expected, $this->date->restoreValue($value));
     }
 
+    /**
+     * Test outputValue
+     */
     public function testOutputValue()
     {
         $this->assertEquals(null, $this->date->outputValue());