[UBP] Add tests and functionality to the Stripe webhook handler

components/public-api-server/pkg/webhooks/stripe.go

@@ -22,6 +22,12 @@ func NewStripeWebhookHandler() *webhookHandler {
 func (h *webhookHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	const maxBodyBytes = int64(65536)
 
+	if req.Method != http.MethodPost {
+		log.Errorf("Bad HTTP method: %s", req.Method)
+		w.WriteHeader(http.StatusBadRequest)
+		return
+	}
+
 	req.Body = http.MaxBytesReader(w, req.Body, maxBodyBytes)
 
 	event := stripe.Event{}
@@ -32,6 +38,12 @@ func (h *webhookHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 		return
 	}
 
+	if event.Type != "invoice.finalized" {
+		log.Errorf("Unexpected Stripe event type: %s", event.Type)
+		w.WriteHeader(http.StatusBadRequest)
+		return
+	}
+
 	// TODO: verify webhook signature.
 	// Conditional on there being a secret configured.
 

components/public-api-server/pkg/webhooks/stripe_test.go

@@ -0,0 +1,117 @@
+// Copyright (c) 2022 Gitpod GmbH. All rights reserved.
+// Licensed under the GNU Affero General Public License (AGPL).
+// See License-AGPL.txt in the project root for license information.
+
+package webhooks
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"testing"
+
+	"github.com/gitpod-io/gitpod/common-go/baseserver"
+	"github.com/stretchr/testify/require"
+	"github.com/stripe/stripe-go/v72"
+)
+
+// https://stripe.com/docs/api/events/types
+const (
+	invoiceUpdatedEventType   = "invoice.updated"
+	invoiceFinalizedEventType = "invoice.finalized"
+	customerCreatedEventType  = "customer.created"
+)
+
+func TestWebhookAcceptsPostRequests(t *testing.T) {
+	scenarios := []struct {
+		HttpMethod         string
+		ExpectedStatusCode int
+	}{
+		{
+			HttpMethod:         http.MethodPost,
+			ExpectedStatusCode: http.StatusOK,
+		},
+		{
+			HttpMethod:         http.MethodGet,
+			ExpectedStatusCode: http.StatusBadRequest,
+		},
+		{
+			HttpMethod:         http.MethodPut,
+			ExpectedStatusCode: http.StatusBadRequest,
+		},
+	}
+
+	srv := baseServerWithStripeWebhook(t)
+
+	ev := stripe.Event{Type: invoiceFinalizedEventType}
+	payload, err := json.Marshal(ev)
+	require.NoError(t, err)
+
+	url := fmt.Sprintf("%s%s", srv.HTTPAddress(), "/webhook")
+
+	for _, scenario := range scenarios {
+		t.Run(scenario.HttpMethod, func(t *testing.T) {
+			req, err := http.NewRequest(scenario.HttpMethod, url, bytes.NewBuffer(payload))
+			require.NoError(t, err)
+
+			resp, err := http.DefaultClient.Do(req)
+			require.NoError(t, err)
+
+			require.Equal(t, scenario.ExpectedStatusCode, resp.StatusCode)
+		})
+	}
+}
+
+func TestWebhookIgnoresIrrelevantEvents(t *testing.T) {
+	scenarios := []struct {
+		EventType          string
+		ExpectedStatusCode int
+	}{
+		{
+			EventType:          invoiceFinalizedEventType,
+			ExpectedStatusCode: http.StatusOK,
+		},
+		{
+			EventType:          invoiceUpdatedEventType,
+			ExpectedStatusCode: http.StatusBadRequest,
+		},
+		{
+			EventType:          customerCreatedEventType,
+			ExpectedStatusCode: http.StatusBadRequest,
+		},
+	}
+
+	srv := baseServerWithStripeWebhook(t)
+
+	url := fmt.Sprintf("%s%s", srv.HTTPAddress(), "/webhook")
+
+	for _, scenario := range scenarios {
+		t.Run(scenario.EventType, func(t *testing.T) {
+			ev := stripe.Event{Type: scenario.EventType}
+			payload, err := json.Marshal(ev)
+			require.NoError(t, err)
+
+			req, err := http.NewRequest(http.MethodPost, url, bytes.NewBuffer(payload))
+			require.NoError(t, err)
+
+			resp, err := http.DefaultClient.Do(req)
+			require.NoError(t, err)
+
+			require.Equal(t, scenario.ExpectedStatusCode, resp.StatusCode)
+		})
+	}
+}
+
+func baseServerWithStripeWebhook(t *testing.T) *baseserver.Server {
+	t.Helper()
+
+	srv := baseserver.NewForTests(t,
+		baseserver.WithHTTP(baseserver.MustUseRandomLocalAddress(t)),
+	)
+	baseserver.StartServerForTests(t, srv)
+
+	srv.HTTPMux().Handle("/webhook", NewStripeWebhookHandler())
+
+	return srv
+}