Add support for the BillingPortal namespace and the Session API a…

…nd resource

billingportal/session/client.go

@@ -0,0 +1,30 @@
+// Package session provides API functions related to checkout sessions.
+package session
+
+import (
+	"net/http"
+
+	stripe "github.com/stripe/stripe-go"
+)
+
+// Client is used to invoke /billing_portal/sessions APIs.
+type Client struct {
+	B   stripe.Backend
+	Key string
+}
+
+// New creates a new session.
+func New(params *stripe.BillingPortalSessionParams) (*stripe.BillingPortalSession, error) {
+	return getC().New(params)
+}
+
+// New creates a new session.
+func (c Client) New(params *stripe.BillingPortalSessionParams) (*stripe.BillingPortalSession, error) {
+	session := &stripe.BillingPortalSession{}
+	err := c.B.Call(http.MethodPost, "/v1/billing_portal/sessions", c.Key, params, session)
+	return session, err
+}
+
+func getC() Client {
+	return Client{stripe.GetBackend(stripe.APIBackend), stripe.Key}
+}

billingportal/session/client_test.go

@@ -0,0 +1,18 @@
+package session
+
+import (
+	"testing"
+
+	assert "github.com/stretchr/testify/require"
+	stripe "github.com/stripe/stripe-go"
+	_ "github.com/stripe/stripe-go/testing"
+)
+
+func TestBillingPortalSessionNew(t *testing.T) {
+	session, err := New(&stripe.BillingPortalSessionParams{
+		Customer:  stripe.String("cus_123"),
+		ReturnURL: stripe.String("https://stripe.com/return"),
+	})
+	assert.Nil(t, err)
+	assert.NotNil(t, session)
+}

billingportal_session.go

@@ -0,0 +1,42 @@
+package stripe
+
+import (
+	"encoding/json"
+)
+
+// BillingPortalSessionParams is the set of parameters that can be used when creating a billing portal session.
+type BillingPortalSessionParams struct {
+	Params    `form:"*"`
+	Customer  *string `form:"customer"`
+	ReturnURL *string `form:"return_url"`
+}
+
+// BillingPortalSession is the resource representing a billing portal session.
+type BillingPortalSession struct {
+	Created   int64  `json:"created"`
+	Customer  string `json:"customer"`
+	ID        string `json:"id"`
+	Livemode  bool   `json:"livemode"`
+	Object    string `json:"object"`
+	ReturnURL string `json:"return_url"`
+	URL       string `json:"url"`
+}
+
+// UnmarshalJSON handles deserialization of a billing portal session.
+// This custom unmarshaling is needed because the resulting
+// property may be an id or the full struct if it was expanded.
+func (p *BillingPortalSession) UnmarshalJSON(data []byte) error {
+	if id, ok := ParseID(data); ok {
+		p.ID = id
+		return nil
+	}
+
+	type session BillingPortalSession
+	var v session
+	if err := json.Unmarshal(data, &v); err != nil {
+		return err
+	}
+
+	*p = BillingPortalSession(v)
+	return nil
+}