Enforce tx history limit

app/scripts/lib/config-manager.js

@@ -5,6 +5,7 @@ const rp = require('request-promise')
 
 const TESTNET_RPC = MetamaskConfig.network.testnet
 const MAINNET_RPC = MetamaskConfig.network.mainnet
+const txLimit = 40
 
 /* The config-manager is a convenience object
  * wrapping a pojo-migrator.
@@ -15,6 +16,8 @@ const MAINNET_RPC = MetamaskConfig.network.mainnet
  */
 module.exports = ConfigManager
 function ConfigManager (opts) {
+  this.txLimit = txLimit
+
   // ConfigManager is observable and will emit updates
   this._subs = []
 
@@ -181,6 +184,9 @@ ConfigManager.prototype._saveTxList = function (txList) {
 
 ConfigManager.prototype.addTx = function (tx) {
   var transactions = this.getTxList()
+  while (transactions.length > this.txLimit - 1) {
+    transactions.shift()
+  }
   transactions.push(tx)
   this._saveTxList(transactions)
 }

test/unit/config-manager-test.js

@@ -233,6 +233,17 @@ describe('config-manager', function() {
         assert.equal(result.length, 1)
         assert.equal(result[0].id, 1)
       })
+
+      it('cuts off early txs beyond a limit', function() {
+        const limit = configManager.txLimit
+        for (let i = 0; i < limit + 1; i++) {
+          let tx = { id: i }
+          configManager.addTx(tx)
+        }
+        var result = configManager.getTxList()
+        assert.equal(result.length, limit, `limit of ${limit} txs enforced`)
+        assert.equal(result[0].id, 1, 'early txs truncted')
+      })
     })
 
     describe('#confirmTx', function() {