1 files changed, 18 insertions, 0 deletions
diff --git a/app/scripts/controllers/network/createLocalhostClient.js b/app/scripts/controllers/network/createLocalhostClient.js
index 09b1d3c1c..3a435e5d0 100644
--- a/app/scripts/controllers/network/createLocalhostClient.js
+++ b/app/scripts/controllers/network/createLocalhostClient.js
@@ -2,9 +2,12 @@ const mergeMiddleware = require('json-rpc-engine/src/mergeMiddleware')
 const createFetchMiddleware = require('eth-json-rpc-middleware/fetch')
 const createBlockRefRewriteMiddleware = require('eth-json-rpc-middleware/block-ref-rewrite')
 const createBlockTrackerInspectorMiddleware = require('eth-json-rpc-middleware/block-tracker-inspector')
+const createAsyncMiddleware = require('json-rpc-engine/src/createAsyncMiddleware')
 const providerFromMiddleware = require('eth-json-rpc-middleware/providerFromMiddleware')
 const BlockTracker = require('eth-block-tracker')
 
+const inTest = process.env.IN_TEST === 'true'
+
 module.exports = createLocalhostClient
 
 function createLocalhostClient () {
@@ -13,9 +16,24 @@ function createLocalhostClient () {
   const blockTracker = new BlockTracker({ provider: blockProvider, pollingInterval: 1000 })
 
   const networkMiddleware = mergeMiddleware([
+    createEstimateGasMiddleware(),
     createBlockRefRewriteMiddleware({ blockTracker }),
     createBlockTrackerInspectorMiddleware({ blockTracker }),
     fetchMiddleware,
   ])
   return { networkMiddleware, blockTracker }
 }
+
+function delay (time) {
+  return new Promise(resolve => setTimeout(resolve, time))
+}
+
+
+function createEstimateGasMiddleware () {
+  return createAsyncMiddleware(async (req, _, next) => {
+    if (req.method === 'eth_estimateGas' && inTest) {
+      await delay(2000)
+    }
+    return next()
+  })
+}