Show a message when logging in with no internet connection.

ECOM-2890

lms/static/js/spec/student_account/login_spec.js

@@ -265,6 +265,21 @@
                 expect(view.$errors).toHaveClass('hidden');
                 expect(authComplete).toBe(true);
             });
+
+            it('displays an error if there is no internet connection', function () {
+                createLoginView(this);
+
+                // Submit the form, with successful validation
+                submitForm(true);
+
+                // Simulate an error from the LMS servers
+                AjaxHelpers.respondWithError(requests, 0);
+
+                // Expect that an error is displayed and that auth complete is not triggered
+                expect(view.$errors).not.toHaveClass('hidden');
+                expect(authComplete).toBe(false);
+                expect(view.$errors.text()).toContain('Please check your internet connection and try again.');
+            });
         });
     });
 }).call(this, define || RequireJS.define);

lms/static/js/student_account/views/LoginView.js

@@ -3,9 +3,10 @@
     define([
             'jquery',
             'underscore',
+            'gettext',
             'js/student_account/views/FormView'
         ],
-        function($, _, FormView) {
+        function($, _, gettext, FormView) {
 
         return FormView.extend({
             el: '#login-form',
@@ -102,7 +103,12 @@
             },
 
             saveError: function( error ) {
-                this.errors = ['<li>' + error.responseText + '</li>'];
+                if (error.status === 0) {
+                    this.errors = ['<li>' + gettext('Please check your internet connection and try again.') + '</li>'];
+                }
+                else {
+                    this.errors = ['<li>' + error.responseText + '</li>'];
+                }
                 this.setErrors();
                 this.element.hide( this.$resetSuccess );