MAGETWO-38611: No validation message is shipping rate is not set

app/code/Magento/Checkout/view/frontend/web/js/view/shipping.js

@@ -69,6 +69,7 @@ define(
                 template: 'Magento_Checkout/shipping'
             },
             visible: ko.observable(!quote.isVirtual()),
+            errorValidationMessage: ko.observable(false),
             isCustomerLoggedIn: customer.isLoggedIn,
             isFormPopUpVisible: formPopUpState.isVisible,
             isFormInline: addressList().length == 0,
@@ -100,12 +101,16 @@ define(
                     stepNavigator.registerStep('shipping', 'Shipping', this.visible, 10);
                 }
 
-                this.isFormPopUpVisible.subscribe(function(value) {
+                this.isFormPopUpVisible.subscribe(function (value) {
                     if (value) {
                         self.getPopUp().openModal();
                     }
                 });
 
+                quote.shippingMethod.subscribe(function (value) {
+                    self.errorValidationMessage(false);
+                });
+
                 return this;
             },
 
@@ -195,7 +200,7 @@ define(
                     emailValidationResult = customer.isLoggedIn();
 
                 if (!quote.shippingMethod()) {
-                    alert($t('Please specify a shipping method'));
+                    this.errorValidationMessage('Please specify a shipping method');
                     return false;
                 }
 

app/code/Magento/Checkout/view/frontend/web/template/shipping.html

@@ -126,6 +126,11 @@
                     <!-- ko template: getTemplate() --><!-- /ko -->
                     <!-- /ko -->
                 </div>
+                <!-- ko if: errorValidationMessage().length > 0 -->
+                <div class="message notice">
+                    <span><!-- ko text: $t(errorValidationMessage())--><!-- /ko --></span>
+                </div>
+                <!-- /ko -->
                 <div class="actions-toolbar" id="shipping-method-buttons-container">
                     <div class="primary">
                         <button data-role="opc-continue" type="submit" class="button action continue primary">