make PAGE_SIZE configurable for Slack API list calls

slack.coffee

@@ -5,6 +5,7 @@ exports.use = (robot) ->
   options =
     token:           process.env.HUBOT_SLACK_TOKEN
     disableUserSync: process.env.DISABLE_USER_SYNC?
+    apiPageSize:     process.env.API_PAGE_SIZE
     # reacts to only messages by insalled workspace users in a shared channel
     installedTeamOnly: process.env.INSTALLED_TEAM_ONLY?
   try

src/bot.coffee

@@ -13,6 +13,7 @@ class SlackBot extends Adapter
   # @param {Object} options - configuration options for the adapter
   # @param {string} options.token - authentication token for Slack APIs
   # @param {Boolean} options.disableUserSync - disables syncing all user data on start
+  # @param {string} options.apiPageSize - sets Slack API page size
   # @param {Boolean} options.installedTeamOnly - reacts to only messages by insalled workspace users in a shared channel
   # @param {Object} options.rtm - RTM configuration options for SlackClient
   # @param {Object} options.rtmStart - options for `rtm.start` Web API method

src/client.coffee

@@ -4,12 +4,6 @@ Promise                = require "bluebird"
 SlackFormatter         = require "./formatter"
 
 class SlackClient
-  ###*
-  # Number used for limit when making paginated requests to Slack Web API list methods
-  # @private
-  ###
-  @PAGE_SIZE = 100
-
   ###*
   # Number of milliseconds which the information returned by `conversations.info` is considered to be valid. The default
   # value is 5 minutes, and it can be customized by setting the `HUBOT_SLACK_CONVERSATION_CACHE_TTL_MS` environment
@@ -28,6 +22,7 @@ class SlackClient
   # @constructor
   # @param {Object} options - Configuration options for this SlackClient instance
   # @param {string} options.token - Slack API token for authentication
+  # @param {string} options.apiPageSize - Number used for limit when making paginated requests to Slack Web API list methods
   # @param {Object} [options.rtm={}] - Configuration options for owned RtmClient instance
   # @param {Object} [options.rtmStart={}] - Configuration options for RtmClient#start() method
   # @param {boolean} [options.noRawText=false] - Deprecated: All SlackTextMessages (subtype of TextMessage) will contain
@@ -42,6 +37,10 @@ class SlackClient
     # this object's API. The property is no longer used internally.
     @rtm = new RtmClient options.token, options.rtm
     @web = new WebClient options.token, { maxRequestConcurrency: 1 }
+
+    @apiPageSize = 100
+    unless isNaN(options.apiPageSize)
+      @apiPageSize = parseInt(options.apiPageSize, 10)
 
     @robot.logger.debug "RtmClient initialized with options: #{JSON.stringify(options.rtm)}"
     @rtmStartOpts = options.rtmStart || {}
@@ -217,13 +216,13 @@ class SlackClient
       if results?.response_metadata?.next_cursor
         # fetch next page
         @web.users.list({
-          limit: SlackClient.PAGE_SIZE,
+          limit: @apiPageSize,
           cursor: results.response_metadata.next_cursor
         }, pageLoaded)
       else
         # pagination complete, run callback with results
         callback(null, combinedResults)
-    @web.users.list({ limit: SlackClient.PAGE_SIZE }, pageLoaded)
+    @web.users.list({ limit: @apiPageSize }, pageLoaded)
 
   ###*
   # Fetch user info from the brain. If not available, call users.info