satellite/payments: coupon expiration bug fixed

Change-Id: Icc89e9ee6a1dd91109d34909490ee446b716e2ed

satellite/payments/coupons.go

@@ -47,15 +47,13 @@ type Coupon struct {
 	Created     time.Time    `json:"created"`
 }
 
-// IsExpired checks if coupon is not after its rollup period.
-func (coupon *Coupon) IsExpired() bool {
-	expirationDate := time.Date(coupon.Created.Year(), coupon.Created.Month(), 1, 0, 0, 0, 0, coupon.Created.Location())
-	expirationDate = expirationDate.AddDate(0, coupon.Duration, 0)
-
-	now := time.Now().UTC()
-	now = time.Date(now.Year(), now.Month(), 1, 0, 0, 0, 0, coupon.Created.Location())
-
-	return expirationDate.Before(now)
+// ExpirationDate returns coupon expiration date.
+//
+// A coupon is valid for Duration number of full months. The month the user
+// signs up is not counted in the duration. The expirated date is at the last
+// day of the last valid month.
+func (coupon *Coupon) ExpirationDate() time.Time {
+	return time.Date(coupon.Created.Year(), coupon.Created.Month()+time.Month(coupon.Duration)+1, 0, 0, 0, 0, 0, time.UTC)
 }
 
 // CouponType indicates the type of the coupon.

satellite/payments/coupons_test.go

@@ -10,28 +10,32 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func TestCouponIsExpired(t *testing.T) {
-	duration := 2
-	now := time.Now()
-
-	testCases := [...]struct {
+func TestCoupon_ExpirationDate(t *testing.T) {
+	for _, tt := range []struct {
 		created  time.Time
-		expected bool
+		duration int
+		expires  time.Time
 	}{
-		{now.AddDate(0, -duration-1, 0), true},
-		{now.AddDate(0, -duration-2, 0), true},
-		{now.AddDate(0, -duration-3, 0), true},
-		{now.AddDate(0, -1, 0), false},
-		{now.AddDate(0, 0, 0), false},
-		{now.AddDate(0, 1, 0), false},
-	}
-
-	for _, tc := range testCases {
+		{
+			created:  time.Date(2020, 1, 30, 0, 0, 0, 0, time.UTC), // 2020-01-30 00:00:00 +0000 UTC
+			duration: 0,                                            // sign-up month only
+			expires:  time.Date(2020, 2, 0, 0, 0, 0, 0, time.UTC),  // 2020-01-31 00:00:00 +0000 UTC
+		},
+		{
+			created:  time.Date(2020, 2, 1, 0, 0, 0, 0, time.UTC), // 2020-02-01 00:00:00 +0000 UTC
+			duration: 1,                                           // sign-up month + 1 full month
+			expires:  time.Date(2020, 4, 0, 0, 0, 0, 0, time.UTC), // 2020-03-31 00:00:00 +0000 UTC
+		},
+		{
+			created:  time.Date(2020, 2, 5, 8, 0, 0, 0, time.UTC), // 2020-02-05 08:00:00 +0000 UTC
+			duration: 2,                                           // sign-up month + 2 full months
+			expires:  time.Date(2020, 5, 0, 0, 0, 0, 0, time.UTC), // 2020-04-30 00:00:00 +0000 UTC
+		},
+	} {
 		coupon := Coupon{
-			Duration: duration,
-			Created:  tc.created,
+			Duration: tt.duration,
+			Created:  tt.created,
 		}
-
-		require.Equal(t, coupon.IsExpired(), tc.expected)
+		require.Equal(t, tt.expires, coupon.ExpirationDate())
 	}
 }

satellite/payments/stripecoinpayments/service.go

@@ -432,7 +432,13 @@ func (service *Service) processCustomers(ctx context.Context, customers []Custom
 		// Apply any promotional credits (a.k.a. coupons) on the remainder.
 		// TODO: if multiple coupons are available apply them in order of expiration.
 		for _, coupon := range coupons {
-			if coupon.IsExpired() {
+			if coupon.Status == payments.CouponExpired {
+				// this coupon has already been marked as expired.
+				continue
+			}
+
+			if end.After(coupon.ExpirationDate()) {
+				// this coupon is identified as expired for first time, mark it in the database
 				if _, err = service.db.Coupons().Update(ctx, coupon.ID, payments.CouponExpired); err != nil {
 					return err
 				}

satellite/payments/stripecoinpayments/service_test.go

@@ -296,7 +296,7 @@ func TestService_InvoiceUserWithManyCoupons(t *testing.T) {
 		var sumUsages int64
 		for i, coupon := range coupons {
 			sumCoupons += coupon.Amount
-			require.False(t, coupon.IsExpired())
+			require.NotEqual(t, payments.CouponExpired, coupon.Status)
 
 			sumUsages += couponsPage.Usages[i].Amount
 			require.Equal(t, stripecoinpayments.CouponUsageStatusUnapplied, couponsPage.Usages[i].Status)