Revert "FIO-8797: set empty day component value to the empty string"

This reverts commit 65a1cfa.

src/WebformBuilder.unit.js

@@ -216,7 +216,7 @@ describe('WebformBuilder tests', function() {
             done();
           }, 200);
         }, 200);
-      }, 300);
+      }, 150);
     }).catch(done);
   });
 

src/components/day/Day.js

@@ -69,10 +69,11 @@ export default class DayComponent extends Field {
 
   /**
    * The empty value for day component.
-   * @returns {''} - The empty value of the day component.
+   *
+   * @return {'00/00/0000'}
    */
   get emptyValue() {
-    return '';
+    return '00/00/0000';
   }
 
   get valueMask() {
@@ -414,7 +415,7 @@ export default class DayComponent extends Field {
   setValueAt(index, value) {
     // temporary solution to avoid input reset
     // on invalid date.
-    if (value === 'Invalid date') {
+    if (!value || value === 'Invalid date') {
       return null;
     }
     const parts = value.split('/');

src/components/day/Day.unit.js

@@ -22,17 +22,6 @@ describe('Day Component', () => {
     });
   });
 
-  it('Should handle blank data correctly', (done) => {
-    Harness.testCreate(DayComponent, comp1).then((component) => {
-      component.setValue();
-      assert.equal(component.getValue(), '');
-      component.checkValidity();
-      assert.equal(component.errors.length, 0, 'Component should be valid with blank data');
-
-      done();
-    });
-  });
-
   it('Should change the max day when the month changes', (done) => {
     Harness.testCreate(DayComponent, comp1).then((component) => {
       Harness.testElements(component, 'option', 13);

test/renders/component-bootstrap-day-html-value0.html

@@ -2,6 +2,6 @@
   <label ref="label" class="col-form-label " for="day-day" id="l-day-day">
     Day
   </label>
-  <div ref="value">-</div>
+  <div ref="value">00/00/0000</div>
   <div ref="messageContainer" class="formio-errors invalid-feedback"></div>
 </div>