diff --git a/src/index.test.ts b/src/index.test.ts
index f3b13a9..6d75441 100644
--- a/src/index.test.ts
+++ b/src/index.test.ts
@@ -1,7 +1,134 @@
 //write tests here
+import { User, UserAPI } from "./index"
 
 describe('Tests will go here!', () => {
-  it('should pass', () => {
-    expect(true).toBeTruthy()
+    let users: UserAPI
+
+    beforeEach(() => {
+      users = new UserAPI()
+    })
+
+  it('gets a user by id', () => {
+    const result = users.getUserById(2)
+
+    expect(result).toStrictEqual({
+        id: 2,
+        name: "Vintage Aaron",
+        age: 35,
+        color: "blue",
+    }) 
+  })
+
+  it.skip('returns null if there is no user matching id', () => {
+      const result = users.getUserById(10)
+
+      expect(result).toStrictEqual(null)
+  })
+
+  it.skip('gets all users', () => {
+    const result = users.getUsers()
+
+    expect(result).toStrictEqual([
+        {
+            id: 1,
+            name: "Michelle",
+            age: 30,
+            color: "rainbow",
+        },
+        {
+            id: 2,
+            name: "Vintage Aaron",
+            age: 35,
+            color: "blue",
+        },
+        {
+            id: 3,
+            name: "Derek",
+            age: 28,
+            color: "green",
+        },
+        {
+            name: "George",
+            age: 32,
+            color: "red",
+        },
+    ]) 
+  }) 
+
+  it.skip('returns null if no users are found', () => {
+      const result = users.getUserById(10)
+
+      expect(result).toStrictEqual(null)
+  })
+
+  it.skip('creates a user', () => {
+    const newUser = {
+        id: 4,
+        name: "Yoda",
+        age: 10,
+        color: "Brown",
+    }
+    const result = users.createUser(newUser)
+
+    expect(result).toStrictEqual({
+        id: 4,
+        name: "Yoda",
+        age: 10,
+        color: "Brown",
+    }) 
+  })
+
+  it.skip('returns null if user id already exists', () => {
+      const result = users.createUser({
+          id: 1,
+          name: "Michelle",
+          color: "rainbow",
+          age: 30,
+      })
+
+      expect(result).toStrictEqual(null)
+  })
+
+  it.skip('deletes a user by id', () => {
+    const result = users.deleteUserById(1)
+
+    expect(result).toStrictEqual({
+        id: 1,
+        name: "Michelle",
+        age: 30,
+        color: "rainbow",
+    }) 
+  })
+
+  it.skip('returns null if deleted user id does not exist', () => {
+    const result = users.deleteUserById(5)
+
+    expect(result).toStrictEqual(false) 
+  })
+
+  it.skip('updates a user by id', () => {
+    const result = users.updateUser(1, { 
+        name: "Michelle",
+        age: 29,
+        color: "red",
+    })
+
+    expect(result).toStrictEqual({
+        id: 1,
+        name: "Michelle",
+        age: 29,
+        color: "red",
+    }) 
+  })
+
+  it.skip('returns null if user with same id already exists', () => {
+    const result = users.updateUser(1, { 
+        id: 2,
+        name: "Michelle",
+        age: 29,
+        color: "red",
+    })
+
+    expect(result).toStrictEqual(null) 
   })
-})
\ No newline at end of file
+})
diff --git a/src/index.ts b/src/index.ts
index bb6b54e..c8d32ce 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1 +1,60 @@
-//Define class here
\ No newline at end of file
+//Define class here
+
+export interface User {
+    readonly id?: number
+    readonly name: string
+    readonly age: number
+    readonly color: string
+}
+
+export class UserAPI {
+    private users: ReadonlyArray<User>
+
+    constructor() {
+        this.users = [
+            {
+                id: 1,
+                name: "Michelle",
+                age: 30,
+                color: "rainbow",
+            },
+            {
+                id: 2,
+                name: "Vintage Aaron",
+                age: 35,
+                color: "blue",
+            },
+            {
+                id: 3,
+                name: "Derek",
+                age: 28,
+                color: "green",
+            },
+            {
+                name: "George",
+                age: 32,
+                color: "red",
+            },
+        ]
+    }
+
+    public getUserById = (id: number): User | null => {
+        console.log("Get user by id")
+    } 
+
+    public getUsers = (): ReadonlyArray<User> | null => {
+        console.log("Get users")
+    }
+
+    public createUser = (user: User): User | null => {
+        console.log("Create user", user)
+    }
+
+    public deleteUserById = (id: number): User | null => {
+        console.log("Create user by id")
+    }
+
+    public updateUser = (id: number, user: User): User | null => {
+        console.log("Update user")
+    }
+ }