diff --git a/README.md b/README.md
index 755fd65..525a25e 100644
--- a/README.md
+++ b/README.md
@@ -314,7 +314,44 @@ Loads a flow then starts the flow. This function has the following arguments:
 * testNode: (object|array of objects) Module object of a node to be tested returned by require function. This node will be registered, and can be used in testFlows.
 * testFlow: (array of objects) Flow data to test a node. If you want to use flow data exported from Node-RED editor, export the flow to the clipboard and paste the content into your test scripts.
 * testCredentials: (object) Optional node credentials.
-* cb: (function) Function to call back when testFlows has been started.
+* cb: (function) Function to call back when testFlows has been started  (not required when called wih `await`)
+
+### setFlows(testFlow, type, testCredentials, cb)
+
+Updates the currently loaded flow. This function has the following arguments:
+
+* testFlow: (array of objects) Flow data to test a node. If you want to use flow data exported from Node-RED editor, export the flow to the clipboard and paste the content into your test scripts.
+* type: (string) Flow data to test a node. If you want to use flow data exported from Node-RED editor, export the flow to the clipboard and paste the content into your test scripts.
+* testCredentials: (object) Optional node credentials.
+* cb: (function) Function to call back when testFlows has been loaded (not required when called wih `await`)
+
+#### Example
+
+```js
+  it('should modify the flow then lower case of payload', async function () {
+      const flow = [
+            { id: "n2", type: "helper" }
+      ]
+      await helper.load(lowerNode, flow)
+      const newFlow = [...flow]
+      newFlow.push( { id: "n1", type: "lower-case", name: "lower-case", wires:[['n2']] },)
+      await helper.setFlows(newFlow, "nodes") //update flows
+      const n1 = helper.getNode('n1')
+      n1.should.have.a.property('name', 'lower-case')
+      await new Promise((resolve, reject) => {
+        const n2 = helper.getNode('n2')
+        n2.on('input', function (msg) {
+            try {
+                msg.should.have.property('payload', 'hello');
+                resolve()
+            } catch (err) {
+                reject(err);
+            }
+        });
+        n1.receive({ payload: 'HELLO' });
+      });
+  });
+```
 
 ### unload()
 
diff --git a/examples/lower-case_spec.js b/examples/lower-case_spec.js
index 5e32a30..bc942cf 100644
--- a/examples/lower-case_spec.js
+++ b/examples/lower-case_spec.js
@@ -54,4 +54,28 @@ describe('lower-case Node', function () {
       n1.receive({ payload: "UpperCase" });
     });
   });
+  it('should modify the flow then lower case of payload', async function () {
+      const flow = [
+            { id: "n2", type: "helper" }
+      ]
+      await helper.load(lowerNode, flow)
+      
+      const newFlow = [...flow]
+      newFlow.push( { id: "n1", type: "lower-case", name: "lower-case", wires:[['n2']] },)
+      await helper.setFlows(newFlow)
+      const n1 = helper.getNode('n1')
+      n1.should.have.a.property('name', 'lower-case')
+      await new Promise((resolve, reject) => {
+        const n2 = helper.getNode('n2')
+        n2.on('input', function (msg) {
+            try {
+                msg.should.have.property('payload', 'hello');
+                resolve()
+            } catch (err) {
+                reject(err);
+            }
+        });
+        n1.receive({ payload: 'HELLO' });
+      });
+  });
 });
diff --git a/index.js b/index.js
index c956922..fa7d3d7 100644
--- a/index.js
+++ b/index.js
@@ -199,15 +199,19 @@ class NodeTestHelper extends EventEmitter {
         });
 
 
-
         if (typeof testCredentials === 'function') {
             cb = testCredentials;
             testCredentials = {};
         }
-
-        var storage = {
+        const conf = {flows:testFlow,credentials:testCredentials|| {}}
+        const storage = {
+            conf: conf,
             getFlows: function () {
-                return Promise.resolve({flows:testFlow,credentials:testCredentials});
+                return Promise.resolve(conf);
+            },
+            saveFlows: function(conf) {
+                storage.conf = conf;
+                return Promise.resolve();
             }
         };
         // this._settings.logging = {console:{level:'off'}};
@@ -281,7 +285,7 @@ class NodeTestHelper extends EventEmitter {
     unload() {
         // TODO: any other state to remove between tests?
         this._redNodes.clearRegistry();
-        this._logSpy.restore();
+        this._logSpy && this._logSpy.restore();
         this._sandbox.restore();
 
         // internal API
@@ -302,6 +306,49 @@ class NodeTestHelper extends EventEmitter {
         return this._redNodes.stopFlows();
     }
 
+    /**
+     * Update flows
+     * @param {object|object[]} testFlow Flow data to test a node
+     * @param {"full"|"flows"|"nodes"} type The type of deploy mode "full", "flows" or "nodes" (defaults to "full") 
+     * @param {object} [testCredentials] Optional node credentials
+     * @param {function} [cb] Optional callback (not required when called with await)
+     * @returns {Promise}
+     */
+    setFlows(testFlow, type, testCredentials, cb) {
+        const helper = this;
+        if (typeof testCredentials === 'string' ) {
+            cb = testCredentials;
+            testCredentials = {};
+        }
+        if(!type || typeof type != "string") {
+            type = "full"
+        }
+        async function waitStarted() {
+            return new Promise((resolve, reject) => {
+                let timeover = setTimeout(() => {
+                    if (timeover) {
+                        timeover = null
+                        reject(Error("timeout waiting event"))
+                    }
+                }, 300);
+                function hander() {
+                    clearTimeout(timeover)
+                    helper._events.off('flows:started', hander)
+                    if (timeover) {
+                        timeover = null
+                        resolve()
+                    }
+                }
+                helper._events.on('flows:started', hander); // call resolve when its done
+            });
+        }
+        return this._redNodes.setFlows(testFlow, testCredentials || {}, type)
+            .then(waitStarted)
+            .then(() => {
+                if(cb) cb();
+            });
+    }
+
     request() {
         return request(this._httpAdmin);
     }
diff --git a/package.json b/package.json
index db9ebbf..b685032 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "node-red-node-test-helper",
-  "version": "0.2.7",
+  "version": "0.3.0",
   "description": "A test framework for Node-RED nodes",
   "main": "index.js",
   "scripts": {
@@ -13,18 +13,18 @@
     "url": "https://github.com/node-red/node-red-node-test-helper.git"
   },
   "dependencies": {
-    "express": "4.17.1",
-    "body-parser": "1.19.0",
+    "body-parser": "1.20.0",
+    "express": "4.18.1",
     "read-pkg-up": "7.0.1",
-    "semver": "7.3.4",
+    "semver": "7.3.7",
     "should": "^13.2.3",
     "should-sinon": "0.0.6",
-    "sinon": "9.2.4",
+    "sinon": "11.1.2",
     "stoppable": "1.1.0",
-    "supertest": "4.0.2"
+    "supertest": "6.2.3"
   },
   "devDependencies": {
-    "mocha": "~7.1.2"
+    "mocha": "9.2.2"
   },
   "contributors": [
     {
@@ -46,6 +46,6 @@
     "node-red"
   ],
   "engines": {
-    "node": ">=8"
+    "node": ">=14"
   }
 }