diff --git a/src/plugins/kibana/server/routes/api/ingest/register_simulate.js b/src/plugins/kibana/server/routes/api/ingest/register_simulate.js
index b0587653766d..e600f9abfd3b 100644
--- a/src/plugins/kibana/server/routes/api/ingest/register_simulate.js
+++ b/src/plugins/kibana/server/routes/api/ingest/register_simulate.js
@@ -1,5 +1,5 @@
 import _ from 'lodash';
-import processESIngestSimulateResponse from '../../../lib/process_es_ingest_simulate_response';
+import handleResponse from '../../../lib/process_es_ingest_simulate_response';
 import processESIngestSimulateError from '../../../lib/process_es_ingest_simulate_error';
 import simulateRequestSchema from '../../../lib/schemas/simulate_request_schema';
 import ingestSimulateApiKibanaToEsConverter from '../../../lib/converters/ingest_simulate_api_kibana_to_es_converter';
@@ -19,7 +19,6 @@ export function registerSimulate(server) {
       const simulateApiDocument = request.payload;
       const body = ingestSimulateApiKibanaToEsConverter(simulateApiDocument);
 
-      const handleResponse = processESIngestSimulateResponse;
       const handleError = _.partial(processESIngestSimulateError, simulateApiDocument.dirty_processor_id);
 
       return boundCallWithRequest('transport.request', {
diff --git a/test/unit/api/ingest/processors/_gsub.js b/test/unit/api/ingest/processors/_gsub.js
new file mode 100644
index 000000000000..d6406d4c113e
--- /dev/null
+++ b/test/unit/api/ingest/processors/_gsub.js
@@ -0,0 +1,67 @@
+define(function (require) {
+  var Promise = require('bluebird');
+  var _ = require('intern/dojo/node!lodash');
+  var expect = require('intern/dojo/node!expect.js');
+
+  const testPipeline = {
+    processors: [{
+      processor_id: 'processor1',
+      type_id: 'gsub',
+      target_field: 'foo',
+      value: 'bar'
+    }],
+    input: {}
+  };
+
+  return function (bdd, scenarioManager, request) {
+    bdd.describe('simulate - set processor', function simulatePipeline() {
+
+      bdd.it('should return 400 for an invalid payload', function invalidPayload() {
+        return Promise.all([
+          // Set processor requires targetField property
+          request.post('/kibana/ingest/simulate')
+          .send({
+            input: {},
+            processors: [{
+              processor_id: 'processor1',
+              type_id: 'set',
+              value: 'bar',
+              target_field: 42
+            }]
+          })
+          .expect(400)
+        ]);
+      });
+
+      bdd.it('should return 200 for a valid simulate request', function validSetSimulate() {
+        return request.post('/kibana/ingest/simulate')
+          .send(testPipeline)
+          .expect(200);
+      });
+
+      bdd.it('should return a simulated output with the correct result for the given processor', function () {
+        return request.post('/kibana/ingest/simulate')
+          .send(testPipeline)
+          .expect(200)
+          .then(function (response) {
+            expect(response.body[0].output.foo).to.be.equal('bar');
+          });
+      });
+
+      bdd.it('should enforce snake case', function setSimulateSnakeCase() {
+        return request.post('/kibana/ingest/simulate')
+        .send({
+          processors: [{
+            processorId: 'processor1',
+            typeId: 'set',
+            targetField: 'foo',
+            value: 'bar'
+          }],
+          input: {}
+        })
+        .expect(400);
+      });
+
+    });
+  };
+});