Fix missing discount label in checkout

[ihor-sviziev]

Description

The discount label was not being shown in the shopping cart totals description
Continuing of #11883

Fixed Issues

1. Discount Rule does not show Default Rule Label #11497: Discount Rule does not show Default Rule Label
2. Cart Price Rule Label is not working #11428: Cart Price Rule Label is not working

Manual testing scenarios

1. Add a discount to quote
2. Go to the shopping cart and now see the discount label in the totals description

Related PRs

#13141
#13223

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[rogyar]

All variables declarations must be at the top of the function scope. Please, try to move the variable declaration to the beginning of the getTitle() function

[rogyar]

I guess, the parenthesis is redundant here. This fact is the reason of failing static tests

[okorshenko]

@rogyar Thank you for the review! 👍

[pemann]

Is this part of the upcoming 2.2.4 release?

[rsantellan]

This fix is part of the release 2.2.4 and now my custom discount is shown but the label discount is not. Is there a way to fix that ? Because it only check the word discount not any thing containing discount.

A possible change could be:

        /**
         * Get discount title
         *
         * @returns {null|String}
         */
        getTitle: function () {
            var discountSegments;

            if (!this.totals()) {
                return null;
            }

            discountSegments = this.totals()['total_segments'].filter(function (segment) {
                return segment.code.indexOf('discount') !== -1;
            });

            return discountSegments.length ? discountSegments[0].title : null;
        },

[ihor-sviziev]

@rsantellan feel free to create PR with your changes