diff --git a/.gitignore b/.gitignore
index 96606c0..c4a95ac 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,4 @@
 node_modules
-coverage
\ No newline at end of file
+coverage
+/.idea/
+.idea
\ No newline at end of file
diff --git a/app.mock.test.js b/app.mock.test.js
index 79b9449..41d6a30 100644
--- a/app.mock.test.js
+++ b/app.mock.test.js
@@ -1,22 +1,20 @@
+
 const createApp = require('./app')
 const request = require('supertest')
 const validateUsername = require('./validation/validateUsername')
 const validatePassword = require('./validation/validatePassword')
 
-//Mock validateEmail to isolate tests
-jest.mock('./validation/validateEmail', () => {
-    return jest.fn((email) => {
-        //Simulate real world simulation
-        if (!email || typeof email !== 'string') return false;
-        const re = /^[^\s@]+@[^\s@]+\.[^\s@]{2,}$/i;
-        return re.test(email);
-    })
-})
-
+// Mock the email validation to avoid the 2-second delay
+jest.mock('./validation/validateEmail')
 const validateEmail = require('./validation/validateEmail')
+
 const app = createApp(validateUsername, validatePassword, validateEmail)
 
 describe('given correct username and password', () => {
+    beforeEach(() => {
+        validateEmail.mockReturnValue(true)
+    })
+
     test('return status 200', async () => {
         const response = await request(app).post('/users').send({
             username: 'Username',
@@ -35,13 +33,39 @@ describe('given correct username and password', () => {
         expect(response.body.userId).toBeDefined();
     })
 
-    // test response content type?
-    // test response message
-    // test response user id value
-    // ...
+    test('returns correct userId value', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.body.userId).toBe('1')
+    })
+
+    test('returns success message', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.body.message).toBe('Valid User')
+    })
+
+    test('response content type is JSON', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.headers['content-type']).toMatch(/json/)
+    })
 })
 
 describe('given incorrect or missing username and password', () => {
+    beforeEach(() => {
+        validateEmail.mockReturnValue(false)
+    })
+
     test('return status 400', async () => {
         const response = await request(app).post('/users').send({
             username: 'user',
@@ -51,9 +75,220 @@ describe('given incorrect or missing username and password', () => {
         expect(response.statusCode).toBe(400)
     })
 
-    // test response message
-    // test that response does NOT have userId
-    // test incorrect username or password according to requirements
-    // test missing username or password
-    // ...
+    test('response does NOT have userId', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'user',
+            password: 'password',
+            email: 'not-an-email'
+        })
+        expect(response.body.userId).toBeUndefined()
+    })
+
+    test('returns error message', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'user',
+            password: 'password',
+            email: 'not-an-email'
+        })
+        expect(response.body.error).toBe('Invalid User')
+    })
+
+    test('rejects username that is too short', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'short',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+        expect(response.body.error).toBe('Invalid User')
+    })
+
+    test('rejects password that is too short', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Pass1',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects password without uppercase letter', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'password123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects password without lowercase letter', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'PASSWORD123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects password without number', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'PasswordABC',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects password with special characters', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password@123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects invalid email format', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123',
+            email: 'not-an-email'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects email without @ symbol', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123',
+            email: 'studentexample.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects email without domain extension', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123',
+            email: 'student@example'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects missing email', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects missing username', async () => {
+        const response = await request(app).post('/users').send({
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects missing password', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+})
+
+describe('valid username requirements', () => {
+    beforeEach(() => {
+        validateEmail.mockReturnValue(true)
+    })
+
+    test('accepts username with 6 characters', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'user12',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(200)
+    })
+
+    test('accepts username with 30 characters', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'user.name.with.dots123456789',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(200)
+    })
+
+    test('accepts username with letters and numbers', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username123',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(200)
+    })
+
+    test('accepts username with periods', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'user.name.test',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(200)
+    })
+
+    test('rejects username with special characters', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'user@name',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects username that is too long', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'user.name.with.too.many.characters.here',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+})
+
+describe('valid email requirements', () => {
+    beforeEach(() => {
+        validateEmail.mockReturnValue(true)
+    })
+
+    test('accepts valid email with .com domain', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123',
+            email: 'user@example.com'
+        })
+        expect(response.statusCode).toBe(200)
+    })
+
+    test('accepts valid email with .edu domain', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123',
+            email: 'student@university.edu'
+        })
+        expect(response.statusCode).toBe(200)
+    })
+
+    test('accepts valid email with .org domain', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123',
+            email: 'contact@organization.org'
+        })
+        expect(response.statusCode).toBe(200)
+    })
 })
\ No newline at end of file
diff --git a/app.test.js b/app.test.js
index f1b561d..67f3da4 100644
--- a/app.test.js
+++ b/app.test.js
@@ -25,10 +25,32 @@ describe('given correct username and password', () => {
         expect(response.body.userId).toBeDefined();
     })
 
-    // test response content type?
-    // test response message
-    // test response user id value
-    // ...
+    test('returns correct userId value', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.body.userId).toBe('1')
+    })
+
+    test('returns success message', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.body.message).toBe('Valid User')
+    })
+
+    test('response content type is JSON', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.headers['content-type']).toMatch(/json/)
+    })
 })
 
 describe('given incorrect or missing username and password', () => {
@@ -41,9 +63,212 @@ describe('given incorrect or missing username and password', () => {
         expect(response.statusCode).toBe(400)
     })
 
-    // test response message
-    // test that response does NOT have userId
-    // test incorrect username or password according to requirements
-    // test missing username or password
-    // ...
+    test('response does NOT have userId', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'user',
+            password: 'password',
+            email: 'not-an-email'
+        })
+        expect(response.body.userId).toBeUndefined()
+    })
+
+    test('returns error message', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'user',
+            password: 'password',
+            email: 'not-an-email'
+        })
+        expect(response.body.error).toBe('Invalid User')
+    })
+
+    test('rejects username that is too short', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'short',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+        expect(response.body.error).toBe('Invalid User')
+    })
+
+    test('rejects password that is too short', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Pass1',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects password without uppercase letter', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'password123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects password without lowercase letter', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'PASSWORD123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects password without number', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'PasswordABC',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects password with special characters', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password@123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects invalid email format', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123',
+            email: 'not-an-email'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects email without @ symbol', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123',
+            email: 'studentexample.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects email without domain extension', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123',
+            email: 'student@example'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects missing email', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects missing username', async () => {
+        const response = await request(app).post('/users').send({
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects missing password', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+})
+
+describe('valid username requirements', () => {
+    test('accepts username with 6 characters', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'user12',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(200)
+    })
+
+    test('accepts username with 30 characters', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'user.name.with.dots123456789',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(200)
+    })
+
+    test('accepts username with letters and numbers', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username123',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(200)
+    })
+
+    test('accepts username with periods', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'user.name.test',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(200)
+    })
+
+    test('rejects username with special characters', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'user@name',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+
+    test('rejects username that is too long', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'user.name.with.too.many.characters.here',
+            password: 'Password123',
+            email: 'student@example.com'
+        })
+        expect(response.statusCode).toBe(400)
+    })
+})
+
+describe('valid email requirements', () => {
+    test('accepts valid email with .com domain', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123',
+            email: 'user@example.com'
+        })
+        expect(response.statusCode).toBe(200)
+    })
+
+    test('accepts valid email with .edu domain', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123',
+            email: 'student@university.edu'
+        })
+        expect(response.statusCode).toBe(200)
+    })
+
+    test('accepts valid email with .org domain', async () => {
+        const response = await request(app).post('/users').send({
+            username: 'Username',
+            password: 'Password123',
+            email: 'contact@organization.org'
+        })
+        expect(response.statusCode).toBe(200)
+    })
 })
\ No newline at end of file
diff --git a/package-lock.json b/package-lock.json
index f07de70..77a5c91 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -48,6 +48,7 @@
       "resolved": "https://registry.npmjs.org/@babel/core/-/core-7.29.0.tgz",
       "integrity": "sha512-CGOfOJqWjg2qW/Mb6zNsDm+u5vFQ8DxXfbM09z69p5Z6+mE1ikP2jUXw+j42Pf1XTYED2Rni5f95npYeuwMDQA==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@babel/code-frame": "^7.29.0",
         "@babel/generator": "^7.29.0",
@@ -1211,6 +1212,7 @@
       "resolved": "https://registry.npmjs.org/acorn/-/acorn-8.8.2.tgz",
       "integrity": "sha512-xjIYgE8HBrkpd/sJqOGNspf8uHG+NOHGOw6a/Urj8taM2EXfdNAH2oFcPeIFfsv3+kz/mJrS5VuMqbNLjCa2vw==",
       "dev": true,
+      "peer": true,
       "bin": {
         "acorn": "bin/acorn"
       },
@@ -1566,6 +1568,7 @@
         }
       ],
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "baseline-browser-mapping": "^2.9.0",
         "caniuse-lite": "^1.0.30001759",
@@ -2131,6 +2134,7 @@
       "resolved": "https://registry.npmjs.org/eslint/-/eslint-8.35.0.tgz",
       "integrity": "sha512-BxAf1fVL7w+JLRQhWl2pzGeSiGqbWumV4WNvc9Rhp6tiCtm4oHnyPBSEtMGZwrQgudFQ+otqzWoPB7x+hxoWsw==",
       "dev": true,
+      "peer": true,
       "dependencies": {
         "@eslint/eslintrc": "^2.0.0",
         "@eslint/js": "8.35.0",
@@ -5920,6 +5924,7 @@
       "version": "7.29.0",
       "resolved": "https://registry.npmjs.org/@babel/core/-/core-7.29.0.tgz",
       "integrity": "sha512-CGOfOJqWjg2qW/Mb6zNsDm+u5vFQ8DxXfbM09z69p5Z6+mE1ikP2jUXw+j42Pf1XTYED2Rni5f95npYeuwMDQA==",
+      "peer": true,
       "requires": {
         "@babel/code-frame": "^7.29.0",
         "@babel/generator": "^7.29.0",
@@ -6749,7 +6754,8 @@
       "version": "8.8.2",
       "resolved": "https://registry.npmjs.org/acorn/-/acorn-8.8.2.tgz",
       "integrity": "sha512-xjIYgE8HBrkpd/sJqOGNspf8uHG+NOHGOw6a/Urj8taM2EXfdNAH2oFcPeIFfsv3+kz/mJrS5VuMqbNLjCa2vw==",
-      "dev": true
+      "dev": true,
+      "peer": true
     },
     "acorn-jsx": {
       "version": "5.3.2",
@@ -6999,6 +7005,7 @@
       "version": "4.28.1",
       "resolved": "https://registry.npmjs.org/browserslist/-/browserslist-4.28.1.tgz",
       "integrity": "sha512-ZC5Bd0LgJXgwGqUknZY/vkUQ04r8NXnJZ3yYi4vDmSiZmC/pdSN0NbNRPxZpbtO4uAfDUAFffO8IZoM3Gj8IkA==",
+      "peer": true,
       "requires": {
         "baseline-browser-mapping": "^2.9.0",
         "caniuse-lite": "^1.0.30001759",
@@ -7393,6 +7400,7 @@
       "resolved": "https://registry.npmjs.org/eslint/-/eslint-8.35.0.tgz",
       "integrity": "sha512-BxAf1fVL7w+JLRQhWl2pzGeSiGqbWumV4WNvc9Rhp6tiCtm4oHnyPBSEtMGZwrQgudFQ+otqzWoPB7x+hxoWsw==",
       "dev": true,
+      "peer": true,
       "requires": {
         "@eslint/eslintrc": "^2.0.0",
         "@eslint/js": "8.35.0",
@@ -9979,4 +9987,4 @@
       "integrity": "sha512-rVksvsnNCdJ/ohGc6xgPwyN8eheCxsiLM8mxuE/t/mOVqJewPuO1miLpTHQiRgTKCLexL4MeAFVagts7HmNZ2Q=="
     }
   }
-}
+}
\ No newline at end of file
diff --git a/validation/validatePassword.js b/validation/validatePassword.js
index 44d8a8b..50912a4 100644
--- a/validation/validatePassword.js
+++ b/validation/validatePassword.js
@@ -1,4 +1,6 @@
 function validatePassword(password) {
+  if (!password || typeof password !== 'string') return false;
+  
   const validLength = password.length >= 8;
   const hasNumber = /[0-9]/g.test(password);
   const hasUpperCaseLetters = /[A-Z]/g.test(password);
@@ -7,4 +9,4 @@ function validatePassword(password) {
 
   return validLength && hasNumber && hasLowerCaseLetters && hasUpperCaseLetters && !hasSpecialCharacters;
 }
-module.exports = validatePassword;
+module.exports = validatePassword;
\ No newline at end of file
diff --git a/validation/validateUsername.js b/validation/validateUsername.js
index 30213b1..889fbc1 100644
--- a/validation/validateUsername.js
+++ b/validation/validateUsername.js
@@ -1,7 +1,9 @@
 function validateUsername(username) {
+  if (!username || typeof username !== 'string') return false;
+  
   const validLength = username.length >= 6 && username.length <=30;
   const allowedcharacters = /^[a-zA-Z0-9.]+$/g.test(username);
 
   return validLength && allowedcharacters;
 }
-module.exports = validateUsername;
+module.exports = validateUsername;
\ No newline at end of file