Feat:discount expiration date (#403)

* discount expiration validation and testing

* integration testing

* double quotes

* add iso8601 package

* api testing

* add joi validation of start and end dates as well as valid_duration

* valid_duration column

* service testing

* discount validation in services

* integration test with invalid date interval

* include valid_duration when fetching a discount

* rename variable for clarity

* add test for dynamic discount with expiration date

* remove debug code

* adjust tests to reflect valid_duration being included in default fields

* additional discount update validation

* fixed failing test

* set ends_at on dynamic discount creation

* discount integration tests

* removed unused console.log

* removed validation of dynamic discounts by duration and added ends_at to dynamic discount creation

* integration tests for dynamic discount with and without duration

* optional valid duration for dynamic discounts

* allow nullable dynamic discount durations

* expect assertions

* fix unit test after change to dynamic discounts without duration

* change to date instead of string

* add assertions

* error handling

* addressed feedback

packages/medusa/src/migrations/1631696624528-valid_duration_for_discount.ts

@@ -0,0 +1,14 @@
+import {MigrationInterface, QueryRunner} from "typeorm";
+
+export class validDurationForDiscount1631696624528 implements MigrationInterface {
+    name = 'validDurationForDiscount1631696624528'
+
+    public async up(queryRunner: QueryRunner): Promise<void> {
+        await queryRunner.query(`ALTER TABLE "discount" ADD "valid_duration" character varying`);
+    }
+
+    public async down(queryRunner: QueryRunner): Promise<void> {
+        await queryRunner.query(`ALTER TABLE "discount" DROP COLUMN "valid_duration"`);
+    }
+
+}