Add test spies

Learn-Node-Tests/package.json

@@ -12,6 +12,7 @@
   "devDependencies": {
     "expect": "^1.20.2",
     "mocha": "^3.0.0",
+    "rewire": "^2.5.2",
     "supertest": "^2.0.0"
   },
   "dependencies": {

Learn-Node-Tests/spies/app.js

@@ -0,0 +1,10 @@
+var db = require('./db.js');
+
+module.exports.handleSignup = (email, password) => {
+    // Check if the email exists
+    db.saveUser({
+        email,
+        password
+    });
+    // Sends the welcome email
+};

Learn-Node-Tests/spies/app.test.js

@@ -0,0 +1,24 @@
+const expect = require('expect');
+const rewire = require('rewire');
+
+var app = rewire('./app.js');
+
+describe('App', () => {
+    var db = {
+        saveUser: expect.createSpy()
+    };
+    app.__set__('db',db);
+    it('should call saveUser with user object', () => {
+        var email = '[email protected]';
+        var password = '123abc';
+
+        app.handleSignup(email,password);
+        expect(db.saveUser).toHaveBeenCalled({email,password});
+    });
+
+    it('should call the spy correctly', () => {
+        var spy = expect.createSpy();
+        spy('Madhav',19);
+        expect(spy).toHaveBeenCalledWith('Madhav',19);
+    });
+});

Learn-Node-Tests/spies/db.js

@@ -0,0 +1,3 @@
+module.exports.saveUser = (user) => {
+    console.log('Saving the user', user);
+};