Bug 1520888 - Ensure spocs don't load over a rec. (#4701)

common/Reducers.jsm

@@ -60,6 +60,7 @@ const INITIAL_STATE = {
       spocs_endpoint: "",
       lastUpdated: null,
       data: {}, // {spocs: []}
+      loaded: false,
     },
   },
   Search: {
@@ -478,6 +479,7 @@ function DiscoveryStream(prevState = INITIAL_STATE.DiscoveryStream, action) {
             ...prevState.spocs,
             lastUpdated: action.data.lastUpdated,
             data: action.data.spocs,
+            loaded: true,
           },
         };
       }

content-src/components/DiscoveryStreamBase/DiscoveryStreamBase.jsx

@@ -115,6 +115,14 @@ export class _DiscoveryStreamBase extends React.PureComponent {
 
   renderComponent(component) {
     let rows;
+    const {spocs} = this.props.DiscoveryStream;
+
+    // TODO: Can we make this a bit better visually while it loads?
+    // If this component expects spocs,
+    // wait until spocs are loaded before attempting to use it.
+    if (component.spocs && !spocs.loaded) {
+      return null;
+    }
 
     switch (component.type) {
       case "TopSites":

lib/DiscoveryStreamFeed.jsm

@@ -168,6 +168,8 @@ this.DiscoveryStreamFeed = class DiscoveryStreamFeed {
         await this.cache.set("spocs", spocs);
       } else {
         Cu.reportError("No response for spocs_endpoint prop");
+        // Use old data if we have it, otherwise nothing.
+        spocs = spocs || {};
       }
     }
 

test/unit/common/Reducers.test.js

@@ -682,6 +682,7 @@ describe("Reducers", () => {
         spocs_endpoint: "",
         data: [1, 2, 3],
         lastUpdated: 123,
+        loaded: true,
       });
     });
     it("should handle no data from DISCOVERY_STREAM_SPOCS_UPDATE", () => {