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+# Test components
+### npm packages
+Node-RED uses the following packages for testing.
+- mocha
+- should
+- sinon
+- supertest
+- istanbul
+
+### Test directory structure
+There are test scripts under test directory (https://github.com/node-red/node-red/tree/master/test).
+Test scripts in `test/nodes` and `test/red` are located in the same hierarchy as the source code in `nodes` and `red`.
+
+`test/resources` is used for storing files that are needed to run a test script. For example, `70-HTML-test-file.html` is used in `70-HTML_spec.js`.
+This directory is also used for creating a temporary directory and/or file (e.g. `50-file_spec.js`).
+
+### Checking the existence of test cases for core components
+`test/_spec.js` traverses under a `red` directory to check if all .js files have a corresponding `_spec.js` test file.
+When adding a code in `red` directory, the corresponding test file also needs to be created.
+
+### Testing environment
+When you develop a feature that depends on OS or browser, please test on the following environments according to the modification.
+
+OS
+- Linux (Ubuntu, Raspbian, etc.)
+- Mac OS X
+- Windows
+
+Browser
+- Chrome
+- Safari
+- Internet Explorer
+- Firefox
+
+
+***
+# Helper node
+
+There is a helper script for testing a node `test/nodes/helper.js`.  When testing a node, it is recommended to use this script.
+Helper script can start Node-RED server, load a flow, and receive a payload from the previous node, etc.
+
+### Starting a server
+`helper.startServer` starts a Node-RED server.  To start a Node-RED server on each test case:
+```
+    beforeEach(function(done) {
+        helper.startServer(done);
+    });
+```
+
+### Loading a flow
+`helper.load` loads a flow then starts the flow. This function has the following arguments in order.
+
+- `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`.
+- `testFlows`: (array of objects) [Flow data](https://github.com/node-red/node-red/wiki/Flow-Format) to test a node. If you want to use the flow data exported from Node-RED editor, need to covert it to JavaScript object using JSON.parse().
+- `testCredentials`: (object) [Node credentials](https://nodered.org/docs/creating-nodes/credentials). This argument is optional.
+- `cb`: (function) Function to call back when testFlows has been started.
+
+The minimum script to test a flow is as follows. This case omits `testCredentials`.
+```
+    var testNode = require("../../../../nodes/core/core/20-inject.js");
+    it('should be loaded', function(done) {
+        var testFlows = [{id:"n1", type:"inject"}];
+        helper.load(testNode, testFlows, function() {
+            var n1 = helper.getNode("n1");
+            done();
+        });
+    });
+```
+
+### Receiving a message
+`helper.getNode` returns a node instance. Any node that is defined in `testFlows` can be retrieved, including `helper` node that is automatically registered when a flow is loaded.
+Helper node is a mock node with no functionality. By adding "input" event, the helper node can receive a message from the previous node and check if its contents are the expected value.
+
+The following is a sample test case to check a message that is sent from `inject` node.
+Once the flow is loaded, "n1" inject node sends a message to "n2" helper node. "n2" node receives a message and checks if the payload is correct.
+
+```
+    it('should send a message', function(done) {
+        var testFlows = [
+            {id:"n1", type:"inject", payload:"hello world!", once: true, wires:[["n2"]] },
+            {id:"n2", type:"helper"}
+        ];
+        helper.load(testNode, testFlows, function() {
+            var n2 = helper.getNode("n2");
+            n2.on("input", function(msg) {
+                msg.should.have.property('payload', 'hello world!');
+                done();
+          });
+        });
+    });
+```
+
+### Unloading a flow
+`helper.unload` clears node registration and context, then stops a flow.
+
+### Stopping a server
+`helper.stopServer` stops a Node-RED server.
+To unload a flow then stop a server:
+
+```
+    afterEach(function(done) {
+        helper.unload().then(function() {
+            helper.stopServer(done);
+        });
+    });
+```
+
+***
+# Testing Node-RED
+
+### Running a test
+You can run test scripts with `grunt` command in the `node-red` directory that is cloned from GitHub.
+
+The following table shows the options for this command.
+
+Option       | Description  
+-------------|-------------
+`default`    | Builds editor content then runs code style checks and unit tests on all components. `default` means to run `grunt` command without option.
+`test-core`  | Runs code style check and unit tests on core runtime code.
+`test-editor`| Runs code style check on editor code.
+`test-nodes` | Runs unit tests on core nodes.
+`clean`      | Deletes build outputs
+`build`      | Builds editor contents
+`dev`        | Developer mode: runs node-red, watches for source changes and rebuilds/restart
+`coverage`   | Runs unit tests on all components, and outputs coverage reports.
+`release`    | Creates distribution zip file - this is the content that will get published to npm when do a release and make available as a zip download via GitHub.
+
+### Testing runtime
+Runtime consists of `nodes` and `red` directories.
+When modified these components, the associated test file should be modified or created if not exists.
+
+#### Running a specific test file
+To run only a specific test script, run the following command in the `node-red` directory:
+
+```
+    npm install -g mocha
+    mocha test/nodes/core/core/20-inject_spec.js
+```
+
+If you cannot install mocha command globally, run the following command as an alternative:
+
+```
+    node node_modules/mocha/bin/mocha test/nodes/core/core/20-inject_spec.js
+```
+
+#### Checking a coverage report
+If a pull request causes the code coverage to decrease it will be rejected unless there is a good reason provided. To run all test cases and output coverage report:
+
+```
+    grunt coverage
+```
+
+Once all tests finished, open `index.html` in `coverage/lcov-report` directory to see the coverage report.
+If the source code that you developed is all covered by test cases, it is ok to send a pull request.
+
+### Testing editor
+Currently, there is no test scripts for Node-RED editor.  When you modify Node-RED editor, you need to test by hand.
+You can run Node-RED with the following command to not minify and uglify scripts so that you can view a code on a browser debugger.
+
+```
+    grunt dev
+```
+
+### Sending a pull request
+After finishing the above procedure, it is ready to send a pull request.  Please read [Contributing to Node-RED](https://nodered.org/about/contribute/) again before sending a pull request.