diff --git a/lesson_15/tdd/tdd_app/src/main/java/com/codedifferently/lesson15/Employee.java b/lesson_15/tdd/tdd_app/src/main/java/com/codedifferently/lesson15/Employee.java
index 49aaabbd7..74e23ea67 100644
--- a/lesson_15/tdd/tdd_app/src/main/java/com/codedifferently/lesson15/Employee.java
+++ b/lesson_15/tdd/tdd_app/src/main/java/com/codedifferently/lesson15/Employee.java
@@ -45,4 +45,8 @@ public double getSalary() {
   public void setSalary(double salary) {
     this.salary = salary;
   }
+
+  public String getDetails() {
+    return id + " " + name + " " + department + " " + salary;
+  }
 }
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..f392c8eaa
--- /dev/null
+++ b/lesson_15/tdd/tdd_app/src/test/java/com/codedifferently/lesson15/EmployeeManagerTest.java
@@ -0,0 +1,76 @@
+package com.codedifferently.lesson15;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+public class EmployeeManagerTest {
+  @Test
+  public void employeeManagerTest() {
+    // Arrange
+    EmployeeManager employeeManager = new EmployeeManager();
+    Employee employee = new Employee(1, "Justin Eklund", "Software Engineer", 0);
+    // Act
+    employeeManager.addEmployee(employee);
+    // Assert
+    assertThat(employeeManager.getEmployeeCount()).isEqualTo(1);
+  }
+
+  @Test
+  public void testAddEmployee() {
+    // Arrange
+    EmployeeManager employeeManager = new EmployeeManager();
+    Employee employee = new Employee(1, "Justin Eklund", "Software Engineer", 0);
+    // Act
+    employeeManager.addEmployee(employee);
+    // Assert
+    assertThat(employeeManager.getEmployeeCount()).isEqualTo(1);
+  }
+
+  @Test
+  public void testGetEmployee() {
+    // Arrange
+    EmployeeManager employeeManager = new EmployeeManager();
+    Employee employee = new Employee(1, "Justin Eklund", "Software Engineer", 0);
+    employeeManager.addEmployee(employee);
+    // Act
+    Employee retrievedEmployee = employeeManager.getEmployee(1);
+    // Assert
+    assertThat(retrievedEmployee).isEqualTo(employee);
+  }
+
+  @Test
+  public void testUpdateEmployee() {
+    // Arrange
+    EmployeeManager employeeManager = new EmployeeManager();
+    Employee employee = new Employee(1, "Justin Eklund", "Software Engineer", 500000);
+    employeeManager.addEmployee(employee);
+    // Act
+    employee.setName("Justin Eklund Updated");
+    employeeManager.updateEmployee(employee);
+    // Assert
+    assertThat(employeeManager.getEmployee(1).getName()).isEqualTo("Justin Eklund Updated");
+  }
+
+  @Test
+  public void testRemoveEmployee() {
+    // Arrange
+    EmployeeManager employeeManager = new EmployeeManager();
+    Employee employee = new Employee(1, "Justin Eklund", "Software Engineer", 0);
+    employeeManager.addEmployee(employee);
+    // Act
+    employeeManager.removeEmployee(1);
+    // Assert
+    assertThat(employeeManager.getEmployeeCount()).isEqualTo(0);
+  }
+
+  @Test
+  public void testAssertEmployeeInCollection() {
+    // Arrange
+    EmployeeManager employeeManager = new EmployeeManager();
+    Employee employee = new Employee(1, "Justin Eklund", "Software Engineer", 0);
+    employeeManager.addEmployee(employee);
+    // Act & Assert
+    assertThat(employeeManager.getEmployee(1)).isEqualTo(employee);
+  }
+}
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..1eb48e120
--- /dev/null
+++ b/lesson_15/tdd/tdd_app/src/test/java/com/codedifferently/lesson15/EmployeeTest.java
@@ -0,0 +1,116 @@
+package com.codedifferently.lesson15;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+public class EmployeeTest {
+
+  @Test
+  public void testGetDetails() {
+    // Arrange
+    Employee employee = new Employee(1, "Justin Eklund", "Software Engineering", 5000000);
+
+    // Act
+    String details = employee.getDetails();
+
+    // Assert
+    assertThat(details).isEqualTo("1 Justin Eklund Software Engineering 5000000.0");
+  }
+
+  @Test
+  public void testGetId() {
+    // Arrange
+    Employee employee = new Employee(1, "Justin Eklund", "Software Engineering", 5000000);
+
+    // Act
+    int id = employee.getId();
+
+    // Assert
+    assertThat(id).isEqualTo(1);
+  }
+
+  @Test
+  public void testSetId() {
+    // Arrange
+    Employee employee = new Employee(1, "Justin Eklund", "Software Engineering", 5000000);
+
+    // Act
+    employee.setId(2);
+
+    // Assert
+    assertThat(employee.getId()).isEqualTo(2);
+  }
+
+  @Test
+  public void testGetName() {
+    // Arrange
+    Employee employee = new Employee(1, "Justin Eklund", "Software Engineering", 5000000);
+
+    // Act
+    String name = employee.getName();
+
+    // Assert
+    assertThat(name).isEqualTo("Justin Eklund");
+  }
+
+  @Test
+  public void testSetName() {
+    // Arrange
+    Employee employee = new Employee(1, "Justin Eklund", "Software Engineering", 5000000);
+
+    // Act
+    employee.setName("Justin Eklund");
+
+    // Assert
+    assertThat(employee.getName()).isEqualTo("Justin Eklund");
+  }
+
+  @Test
+  public void testGetDepartment() {
+    // Arrange
+    Employee employee = new Employee(1, "Justin Eklund", "Software Engineering", 5000000);
+
+    // Act
+    String department = employee.getDepartment();
+
+    // Assert
+    assertThat(department).isEqualTo("Software Engineering");
+  }
+
+  @Test
+  public void testSetDepartment() {
+    // Arrange
+    Employee employee = new Employee(1, "Justin Eklund", "Software Engineering", 5000000);
+
+    // Act
+    employee.setDepartment("Engineering");
+
+    // Assert
+    assertThat(employee.getDepartment()).isEqualTo("Engineering");
+  }
+
+  @Test
+  public void testGetSalary() {
+    // Arrange
+    Employee employee = new Employee(1, "Justin Eklund", "Software Engineering", 5000000);
+
+    // Act
+    double salary = employee.getSalary();
+
+    // Assert
+    assertThat(salary).isEqualTo(5000000);
+  }
+
+  @Test
+  public void testSetSalary() {
+    // Arrange
+    Employee employee = new Employee(1, "Justin Eklund", "Software Engineering", 5000000);
+
+    // Act
+    employee.setSalary(5000000);
+
+    // Assert
+    assertThat(employee.getSalary()).isEqualTo(5000000);
+  }
+}
diff --git a/lesson_15/tdd/tdd_app/src/test/java/com/codedifferently/lesson15/Lesson15Test.java b/lesson_15/tdd/tdd_app/src/test/java/com/codedifferently/lesson15/Lesson15Test.java
index cd6ef511e..0be6093d4 100644
--- a/lesson_15/tdd/tdd_app/src/test/java/com/codedifferently/lesson15/Lesson15Test.java
+++ b/lesson_15/tdd/tdd_app/src/test/java/com/codedifferently/lesson15/Lesson15Test.java
@@ -10,10 +10,4 @@ class Lesson15Test {
   public void testLesson15() {
     assertThat(new Lesson15()).isNotNull();
   }
-
-  @Test
-  public void testGetGreeting() {
-    // Act
-    Lesson15.main(null);
-  }
 }