Attempt to fix the tests

lighthouse-core/gather/gatherers/offline.js

@@ -59,9 +59,8 @@ class Offline extends Gatherer {
       // If options.url is just an origin without a path, the Chrome will
       // implicitly add in a path of '/'.
       return (record._url === options.url || record._url === options.url + '/') &&
-        record._initiator.type === 'other' &&
         record._fetchedViaServiceWorker;
-    })[0];
+    }).pop(); // Take the last record that matches.
 
     this.artifact = navigationRecord ? navigationRecord.statusCode : -1;
   }

lighthouse-core/test/gather/gatherers/offline-test.js

@@ -19,40 +19,22 @@
 
 const OfflineGather = require('../../../gather/gatherers/offline');
 const assert = require('assert');
+const tracingData = require('../../fixtures/traces/network-records.json');
 let offlineGather;
 
-describe('HTTP Redirect gatherer', () => {
+describe('Offline gatherer', () => {
   // Reset the Gatherer before each test.
   beforeEach(() => {
     offlineGather = new OfflineGather();
   });
 
-  it('returns an artifact', () => {
-    return offlineGather.afterPass({
-      driver: {
-        sendCommand() {
-          return Promise.resolve();
-        },
-        evaluateAsync() {
-          return Promise.resolve({offlineResponseCode: 200});
-        }
-      }
-    }).then(_ => {
-      assert.deepEqual(offlineGather.artifact, {offlineResponseCode: 200});
-    });
+  it('returns an artifact set to -1 when offline loading fails', () => {
+    offlineGather.afterPass({url: 'https://do-not-match.com'}, tracingData);
+    assert.deepEqual(offlineGather.artifact, -1);
   });
 
-  it('handles driver sendCommand() failure', () => {
-    return offlineGather.afterPass({
-      driver: {
-        sendCommand() {
-          return Promise.reject('such a fail');
-        }
-      }
-    }).then(_ => {
-      assert(false);
-    }).catch(_ => {
-      assert.deepEqual(offlineGather.artifact, {offlineResponseCode: -1});
-    });
+  it('returns an artifact set to 200 when offline loading succeeds', () => {
+    offlineGather.afterPass({url: 'https://ifixit-pwa.appspot.com'}, tracingData);
+    assert.deepEqual(offlineGather.artifact, 200);
   });
 });