Add users repository in users module.

src/modules/users.js

 import timelineFetcher from '../services/timeline_fetcher/timeline_fetcher.service.js'
 import backendInteractorService from '../services/backend_interactor_service/backend_interactor_service.js'
+import { map, each, find, merge } from 'lodash'
 
-const users = {
-  state: {
-    currentUser: false,
-    loggingIn: false
+// TODO: Unify with mergeOrAdd in statuses.js
+export const mergeOrAdd = (arr, item) => {
+  const oldItem = find(arr, {id: item.id})
+  if (oldItem) {
+    // We already have this, so only merge the new info.
+    merge(oldItem, item)
+    return {item: oldItem, new: false}
+  } else {
+    // This is a new item, prepare it
+    arr.push(item)
+    return {item, new: true}
+  }
+}
+
+export const mutations = {
+  setCurrentUser (state, user) {
+    state.currentUser = user
   },
-  mutations: {
-    setCurrentUser (state, user) {
-      state.currentUser = user
-    },
-    beginLogin (state) {
-      state.loggingIn = true
-    },
-    endLogin (state) {
-      state.loggingIn = false
-    }
+  beginLogin (state) {
+    state.loggingIn = true
+  },
+  endLogin (state) {
+    state.loggingIn = false
   },
+  addNewUsers (state, users) {
+    each(users, (user) => mergeOrAdd(state.users, user))
+  }
+}
+
+export const defaultState = {
+  currentUser: false,
+  loggingIn: false,
+  users: []
+}
+
+const users = {
+  state: defaultState,
+  mutations,
   actions: {
+    addNewStatuses (store, { statuses }) {
+      const users = map(statuses, 'user')
+      store.commit('addNewUsers', users)
+    },
     loginUser (store, userCredentials) {
       const commit = store.commit
       commit('beginLogin')

test/unit/specs/modules/users.spec.js

+import { cloneDeep } from 'lodash'
+
+import { defaultState, mutations } from '../../../../src/modules/users.js'
+
+describe('The users module', () => {
+  it('adds new users to the set, merging in new information for old users', () => {
+    const state = cloneDeep(defaultState)
+    const user = { id: 1, name: 'Guy' }
+    const modUser = { id: 1, name: 'Dude' }
+
+    mutations.addNewUsers(state, [user])
+    expect(state.users).to.have.length(1)
+    expect(state.users).to.eql([user])
+
+    mutations.addNewUsers(state, [modUser])
+    expect(state.users).to.have.length(1)
+    expect(state.users).to.eql([user])
+    expect(state.users[0].name).to.eql('Dude')
+  })
+})