Add generateTestHeaderStringAsync function to Webhooks.ts

src/Webhooks.ts

@@ -65,6 +65,9 @@
     receivedAt: number
   ) => Promise<WebhookEvent>;
   generateTestHeaderString: (opts: WebhookTestHeaderOptions) => string;
+  generateTestHeaderStringAsync: (
+    opts: WebhookTestHeaderOptions
+  ) => Promise<string>;
 };
 
 export function createWebhooks(
@@ -142,31 +145,30 @@
      * @property {CryptoProvider} cryptoProvider - Crypto provider to use for computing the signature if none was provided. Defaults to NodeCryptoProvider.
      */
     generateTestHeaderString: function(opts: WebhookTestHeaderOptions): string {
-      if (!opts) {
-        throw new StripeError({
-          message: 'Options are required',
-        });
-      }
-
-      opts.timestamp =
-        Math.floor(opts.timestamp) || Math.floor(Date.now() / 1000);
-      opts.scheme = opts.scheme || signature.EXPECTED_SCHEME;
-
-      opts.cryptoProvider = opts.cryptoProvider || getCryptoProvider();
+      const preparedOpts = prepareOptions(opts);
 
-      opts.signature =
-        opts.signature ||
-        opts.cryptoProvider.computeHMACSignature(
-          opts.timestamp + '.' + opts.payload,
-          opts.secret
+      const signature =
+        preparedOpts.signature ||
+        preparedOpts.cryptoProvider.computeHMACSignature(
+          preparedOpts.payloadString,
+          preparedOpts.secret
         );
 
-      const generatedHeader = [
-        't=' + opts.timestamp,
-        opts.scheme + '=' + opts.signature,
-      ].join(',');
-
-      return generatedHeader;
+      return preparedOpts.generateHeaderString(signature);
+    },
+    generateTestHeaderStringAsync: async function(
+      opts: WebhookTestHeaderOptions
+    ) {
+      const preparedOpts = prepareOptions(opts);
+
+      const signature =
+        preparedOpts.signature ||
+        (await preparedOpts.cryptoProvider.computeHMACSignatureAsync(
+          preparedOpts.payloadString,
+          preparedOpts.secret
+        ));
+
+      return preparedOpts.generateHeaderString(signature);
     },
   };
 
@@ -440,9 +442,41 @@
     if (!webhooksCryptoProviderInstance) {
       webhooksCryptoProviderInstance = platformFunctions.createDefaultCryptoProvider();
     }
     return webhooksCryptoProviderInstance!;
   }
 
+  function prepareOptions(
+    opts: WebhookTestHeaderOptions
+  ): WebhookTestHeaderOptions & {
+    payloadString: string;
+    generateHeaderString: (signature: string) => string;
+  } {
+    if (!opts) {
+      throw new StripeError({
+        message: 'Options are required',
+      });
+    }
+
+    const timestamp =
+      Math.floor(opts.timestamp) || Math.floor(Date.now() / 1000);
+    const scheme = opts.scheme || signature.EXPECTED_SCHEME;
+    const cryptoProvider = opts.cryptoProvider || getCryptoProvider();
+    const payloadString = `${timestamp}.${opts.payload}`;
+
+    const generateHeaderString = (signature: string): string => {
+      return `t=${timestamp},${scheme}=${signature}`;
+    };
+
+    return {
+      ...opts,
+      timestamp,
+      scheme,
+      cryptoProvider,
+      payloadString,
+      generateHeaderString,
+    };
+  }
+
   Webhook.signature = signature;
 
   return Webhook;

test/Webhook.spec.ts

@@ -41,6 +41,30 @@ function createWebhooksTestSuite(stripe) {
     });
   });
 
+  describe('.generateTestHeaderStringAsync', () => {
+    it('should throw when no opts are passed', async () => {
+      await expect(
+        stripe.webhooks.generateTestHeaderStringAsync()
+      ).to.be.rejectedWith('Options are required');
+    });
+
+    it('should correctly construct a webhook header', async () => {
+      const header = await stripe.webhooks.generateTestHeaderStringAsync({
+        payload: EVENT_PAYLOAD_STRING,
+        secret: SECRET,
+      });
+
+      expect(header).to.not.be.undefined;
+      expect(header.split(',')).to.have.lengthOf(2);
+      expect(header).to.equal(
+        stripe.webhooks.generateTestHeaderString({
+          payload: EVENT_PAYLOAD_STRING,
+          secret: SECRET,
+        })
+      );
+    });
+  });
+
   const makeConstructEventTests = (
     constructEventFn: typeof stripe.webhooks.construct
   ) => {