Move aggregation code to dedicated function

src/components/views/elements/MemberEventListSummary.js

@@ -301,6 +301,46 @@ module.exports = React.createClass({
         }
     },
 
+    _getAggregate: function(userEvents) {
+        // A map of aggregate type to arrays of display names. Each aggregate type
+        // is a comma-delimited string of transitions, e.g. "joined,left,kicked".
+        // The array of display names is the array of users who went through that
+        // sequence during eventsToRender.
+        let aggregate = {
+            // $aggregateType : []:string
+        };
+        // A map of aggregate types to the indices that order them (the index of
+        // the first event for a given transition sequence)
+        let aggregateIndices = {
+            // $aggregateType : int
+        };
+
+        let users = Object.keys(userEvents);
+        users.forEach(
+            (userId) => {
+                let firstEvent = userEvents[userId][0];
+                let displayName = firstEvent.displayName;
+
+                let seq = this._getTransitionSequence(userEvents[userId]);
+                if (!aggregate[seq]) {
+                    aggregate[seq] = [];
+                    aggregateIndices[seq] = -1;
+                }
+
+                aggregate[seq].push(displayName);
+
+                if (aggregateIndices[seq] === -1 || firstEvent.index < aggregateIndices[seq]) {
+                    aggregateIndices[seq] = firstEvent.index;
+                }
+            }
+        );
+
+        return {
+            names: aggregate,
+            indices: aggregateIndices,
+        };
+    },
+
     render: function() {
         let eventsToRender = this.props.events;
         let fewEvents = eventsToRender.length < this.props.threshold;
@@ -346,46 +386,13 @@ module.exports = React.createClass({
             });
         });
 
-        // A map of aggregate type to arrays of display names. Each aggregate type
+        let aggregate = this._getAggregate(userEvents);
-        // is a comma-delimited string of transitions, e.g. "joined,left,kicked".
-        // The array of display names is the array of users who went through that
-        // sequence during eventsToRender.
-        let aggregate = {
-            // $aggregateType : []:string
-        };
-        // A map of aggregate types to the indices that order them (the index of
-        // the first event for a given transition sequence)
-        let aggregateIndices = {
-            // $aggregateType : int
-        };
-
-        let users = Object.keys(userEvents);
-        users.forEach(
-            (userId) => {
-                let firstEvent = userEvents[userId][0];
-                let displayName = firstEvent.displayName;
-
-                let seq = this._getTransitionSequence(userEvents[userId]);
-                if (!aggregate[seq]) {
-                    aggregate[seq] = [];
-                    aggregateIndices[seq] = -1;
-                }
-
-                if (aggregate[seq].indexOf(displayName) === -1) {
-                    aggregate[seq].push(displayName);
-                }
-
-                if (aggregateIndices[seq] === -1 || firstEvent.index < aggregateIndices[seq]) {
-                    aggregateIndices[seq] = firstEvent.index;
-                }
-            }
-        );
 
         // Sort types by order of lowest event index within sequence
-        let orderedTransitionSequences = Object.keys(aggregate).sort((seq1, seq2) => aggregateIndices[seq1] > aggregateIndices[seq2]);
+        let orderedTransitionSequences = Object.keys(aggregate.names).sort((seq1, seq2) => aggregate.indices[seq1] > aggregate.indices[seq2]);
 
         let avatars = this._renderAvatars(avatarMembers);
-        let summary = this._renderSummary(aggregate, orderedTransitionSequences);
+        let summary = this._renderSummary(aggregate.names, orderedTransitionSequences);
         let toggleButton = (
             <a className="mx_MemberEventListSummary_toggle" onClick={this._toggleSummary}>
                 {expanded ? 'collapse' : 'expand'}

test/components/views/elements/MemberEventListSummary-test.js

@@ -6,7 +6,7 @@ const sdk = require('matrix-react-sdk');
 const MemberEventListSummary = sdk.getComponent('views.elements.MemberEventListSummary');
 
 const testUtils = require('../../../test-utils');
-describe('MemberEventListSummary', function() {
+describe.only('MemberEventListSummary', function() {
     let sandbox;
     let parentDiv;