diff --git a/lesson_15/tdd/tdd_app/src/test/java/com/codedifferently/lesson15/EmployeeManagerTest.java b/lesson_15/tdd/tdd_app/src/test/java/com/codedifferently/lesson15/EmployeeManagerTest.java
new file mode 100644
index 000000000..d5d8cd134
--- /dev/null
+++ b/lesson_15/tdd/tdd_app/src/test/java/com/codedifferently/lesson15/EmployeeManagerTest.java
@@ -0,0 +1,55 @@
+package com.codedifferently.lesson15;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class EmployeeManagerTest {
+
+  @Test
+  public void testAddEmployee() {
+    EmployeeManager manager = new EmployeeManager();
+    Employee employee = new Employee(1, "John Doe", "Engineering", 60000);
+    manager.addEmployee(employee);
+    assertEquals(1, manager.getEmployeeCount());
+  }
+
+  @Test
+  public void testGetEmployee() {
+    EmployeeManager manager = new EmployeeManager();
+    Employee employee = new Employee(1, "John Doe", "Engineering", 60000);
+    manager.addEmployee(employee);
+    Employee retrievedEmployee = manager.getEmployee(1);
+    assertEquals(employee, retrievedEmployee);
+  }
+
+  @Test
+  public void testUpdateEmployee() {
+    EmployeeManager manager = new EmployeeManager();
+    Employee employee = new Employee(1, "John Doe", "Engineering", 60000);
+    manager.addEmployee(employee);
+    employee.setName("Jane Doe");
+    manager.updateEmployee(employee);
+    Employee updatedEmployee = manager.getEmployee(1);
+    assertEquals("Jane Doe", updatedEmployee.getName());
+  }
+
+  @Test
+  public void testRemoveEmployee() {
+    EmployeeManager manager = new EmployeeManager();
+    Employee employee = new Employee(1, "John Doe", "Engineering", 60000);
+    manager.addEmployee(employee);
+    manager.removeEmployee(1);
+    assertEquals(0, manager.getEmployeeCount());
+  }
+
+  @Test
+  public void testGetEmployeeCount() {
+    EmployeeManager manager = new EmployeeManager();
+    Employee employee1 = new Employee(1, "John Doe", "Engineering", 60000);
+    Employee employee2 = new Employee(2, "Jane Doe", "Marketing", 70000);
+    manager.addEmployee(employee1);
+    manager.addEmployee(employee2);
+    assertEquals(2, manager.getEmployeeCount());
+  }
+}
diff --git a/lesson_15/tdd/tdd_app/src/test/java/com/codedifferently/lesson15/EmployeeTest.java b/lesson_15/tdd/tdd_app/src/test/java/com/codedifferently/lesson15/EmployeeTest.java
new file mode 100644
index 000000000..c2d2c6fb9
--- /dev/null
+++ b/lesson_15/tdd/tdd_app/src/test/java/com/codedifferently/lesson15/EmployeeTest.java
@@ -0,0 +1,54 @@
+package com.codedifferently.lesson15;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class EmployeeTest {
+  private Employee employee;
+
+  @Test
+  public void testGetId() {
+    employee = new Employee(1, "John Doe", "Engineering", 60000);
+    assertEquals(1, employee.getId());
+  }
+
+  @Test
+  public void testSetId() {
+    employee = new Employee(1, "John Doe", "Engineering", 60000);
+    employee.setId(2);
+    assertEquals(2, employee.getId());
+  }
+
+  @Test
+  public void testGetName() {
+    employee = new Employee(1, "John Doe", "Engineering", 60000);
+    assertEquals("John Doe", employee.getName());
+  }
+
+  @Test
+  public void testSetName() {
+    employee = new Employee(1, "John Doe", "Engineering", 60000);
+    employee.setName("Jane Doe");
+    assertEquals("Jane Doe", employee.getName());
+  }
+
+  @Test
+  public void testGetDepartment() {
+    employee = new Employee(1, "John Doe", "Engineering", 60000);
+    assertEquals("Engineering", employee.getDepartment());
+  }
+
+  @Test
+  public void testGetSalary() {
+    employee = new Employee(1, "John Doe", "Engineering", 60000);
+    assertEquals(60000, employee.getSalary(), 0.01);
+  }
+
+  @Test
+  public void testSetSalary() {
+    employee = new Employee(1, "John Doe", "Engineering", 60000);
+    employee.setSalary(70000);
+    assertEquals(70000, employee.getSalary(), 0.01);
+  }
+}