fix: don't overwrite an Urgency header supplied via the headers option

src/web-push-lib.js

@@ -104,7 +104,7 @@ export class WebPushLib {
     let timeToLive = DEFAULT_TTL;
     let extraHeaders = {};
     let contentEncoding = webPushConstants.supportedContentEncodings.AES_128_GCM;
-    let urgency = webPushConstants.supportedUrgency.NORMAL;
+    let urgency;
     let topic;
     let proxy;
     let agent;
@@ -223,10 +223,13 @@ export class WebPushLib {
       timeToLive = DEFAULT_TTL;
     }
 
+    // Defaults are seeded first so that anything supplied through the
+    // `headers` option can override them.
     const requestDetails = {
       method: 'POST',
       headers: {
-        TTL: timeToLive
+        TTL: timeToLive,
+        Urgency: webPushConstants.supportedUrgency.NORMAL
       }
     };
     Object.keys(extraHeaders).forEach(function (header) {
@@ -292,7 +295,9 @@ export class WebPushLib {
       requestDetails.headers.Authorization = 'key=' + currentGCMAPIKey;
     }
 
-    requestDetails.headers.Urgency = urgency;
+    if (urgency) {
+      requestDetails.headers.Urgency = urgency;
+    }
 
     if (topic) {
       requestDetails.headers.Topic = topic;

test/test-generate-request-details.js

@@ -255,7 +255,9 @@ suite('Test Generate Request Details', function() {
       TTL: 100,
       headers: {
         'Topic': 'topic',
-        'Urgency': 'normal'
+        // Deliberately not the default urgency, so that this assertion can
+        // actually fail if the header is overwritten.
+        'Urgency': 'high'
       }
     };
     let details = generateRequestDetails(
@@ -268,6 +270,28 @@ suite('Test Generate Request Details', function() {
     assert.equal(details.headers.Urgency, extraOptions.headers.Urgency);
   });
 
+  test('Default urgency is used when no urgency is supplied', function() {
+    const subscription = { endpoint: 'https://127.0.0.1:8080' };
+
+    const details = generateRequestDetails(subscription, undefined, {});
+
+    assert.equal(details.headers.Urgency, 'normal');
+  });
+
+  test('Urgency option takes precedence over an Urgency extra header', function() {
+    const subscription = { endpoint: 'https://127.0.0.1:8080' };
+    const extraOptions = {
+      urgency: 'low',
+      headers: {
+        'Urgency': 'high'
+      }
+    };
+
+    const details = generateRequestDetails(subscription, undefined, extraOptions);
+
+    assert.equal(details.headers.Urgency, extraOptions.urgency);
+  });
+
   test('Audience contains port with aes128gcm', function() {
     const subscription = {
       endpoint: 'http://example.com:4242/life-universe-and-everything'