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..63c5d11d0 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
@@ -22,6 +22,26 @@ public void setId(int id) {
     this.id = id;
   }
 
+  // Method to get all details of an employee
+  public String getDetails() {
+    return "The Employee's ID: "
+        + id
+        + " Name: "
+        + name
+        + " Department: "
+        + department
+        + " Salary: "
+        + salary;
+  }
+
+  // Method to set all employee details at once
+  public void setDetails(String name, String department, double salary, int id) {
+    this.id = id;
+    this.name = name;
+    this.department = department;
+    this.salary = salary;
+  }
+
   public String getName() {
     return name;
   }
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..209ea0810
--- /dev/null
+++ b/lesson_15/tdd/tdd_app/src/test/java/com/codedifferently/lesson15/EmployeeManagerTest.java
@@ -0,0 +1,69 @@
+package com.codedifferently.lesson15;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+public class EmployeeManagerTest {
+
+  @Test
+  public void testAddEmployee() {
+    EmployeeManager employeeManager = new EmployeeManager();
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    employeeManager.addEmployee(employee);
+    assertThat(employeeManager.getEmployeeCount()).isEqualTo(1);
+  }
+
+  @Test
+  public void testGetEmployee() {
+    EmployeeManager employeeManager = new EmployeeManager();
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    employeeManager.addEmployee(employee);
+    Employee result = employeeManager.getEmployee(1);
+    assertThat(result).isEqualTo(employee);
+  }
+
+  @Test
+  public void testUpdateEmployee() {
+    EmployeeManager employeeManager = new EmployeeManager();
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    employeeManager.addEmployee(employee);
+    employee.setName("Jane Doe");
+    employeeManager.updateEmployee(employee);
+    Employee result = employeeManager.getEmployee(1);
+    assertThat(result.getName()).isEqualTo("Jane Doe");
+  }
+
+  @Test
+  public void testRemoveEmployee() {
+    EmployeeManager employeeManager = new EmployeeManager();
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    employeeManager.addEmployee(employee);
+    employeeManager.removeEmployee(1);
+    assertThat(employeeManager.getEmployeeCount()).isEqualTo(0);
+  }
+
+  @Test
+  public void testEmployeeCount() {
+    EmployeeManager employeeManager = new EmployeeManager();
+    Employee employee1 = new Employee(1, "John Doe", "Engineering", 50000);
+    Employee employee2 = new Employee(2, "Jane Doe", "Marketing", 60000);
+    employeeManager.addEmployee(employee1);
+    employeeManager.addEmployee(employee2);
+    int result = employeeManager.getEmployeeCount();
+    assertThat(result).isEqualTo(2);
+  }
+
+  @Test
+  public void assertEmployeeInCollection() {
+    EmployeeManager employeeManager = new EmployeeManager();
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    employeeManager.addEmployee(employee);
+    try {
+      employeeManager.getEmployee(1);
+    } catch (IllegalArgumentException e) {
+      // This should not happen
+      assertThat(e.getMessage()).isEqualTo("Employee does not exist in collection with id 1");
+    }
+  }
+}
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..2327de1f7
--- /dev/null
+++ b/lesson_15/tdd/tdd_app/src/test/java/com/codedifferently/lesson15/EmployeeTest.java
@@ -0,0 +1,89 @@
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.codedifferently.lesson15.Employee;
+import org.junit.jupiter.api.Test;
+
+public class EmployeeTest {
+
+  @Test
+  public void testGetDetails() {
+    // Create an instance of Employee by adding in temporary values
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    // This will call the getDetails method and store that in a variable called result
+    String result = employee.getDetails();
+    // This will create a string that we expect the getDetails method to return
+    String expected = "The Employee's ID: 1 Name: John Doe Department: Engineering Salary: 50000.0";
+    // This will compare the result of the getDetails method to the expected string
+    assertThat(result).isEqualTo(expected);
+  }
+
+  @Test
+  public void testSetDetails() {
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    employee.setDetails("Jane Doe", "Marketing", 60000, 1);
+
+    String result = employee.getDetails();
+    String expected = "The Employee's ID: 1 Name: Jane Doe Department: Marketing Salary: 60000.0";
+    assertThat(result).isEqualTo(expected);
+  }
+
+  @Test
+  public void testGetId() {
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    int result = employee.getId();
+    assertThat(result).isEqualTo(1);
+  }
+
+  @Test
+  public void testSetId() {
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    employee.setId(2);
+    int result = employee.getId();
+    assertThat(result).isEqualTo(2);
+  }
+
+  @Test
+  public void testGetName() {
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    String result = employee.getName();
+    assertThat(result).isEqualTo("John Doe");
+  }
+
+  @Test
+  public void testSetName() {
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    employee.setName("Jane Doe");
+    String result = employee.getName();
+    assertThat(result).isEqualTo("Jane Doe");
+  }
+
+  @Test
+  public void testGetDepartment() {
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    String result = employee.getDepartment();
+    assertThat(result).isEqualTo("Engineering");
+  }
+
+  @Test
+  public void testSetDepartment() {
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    employee.setDepartment("Marketing");
+    String result = employee.getDepartment();
+    assertThat(result).isEqualTo("Marketing");
+  }
+
+  @Test
+  public void testGetSalary() {
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    double result = employee.getSalary();
+    assertThat(result).isEqualTo(50000);
+  }
+
+  @Test
+  public void testSetSalary() {
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    employee.setSalary(60000);
+    double result = employee.getSalary();
+    assertThat(result).isEqualTo(60000);
+  }
+}
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..ac2385f38 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
@@ -1,7 +1,6 @@
 package com.codedifferently.lesson15;
 
 import static org.assertj.core.api.Assertions.assertThat;
-
 import org.junit.jupiter.api.Test;
 
 class Lesson15Test {
@@ -11,9 +10,81 @@ public void testLesson15() {
     assertThat(new Lesson15()).isNotNull();
   }
 
+  // ------------
+  // Tests for Employee class
+  @Test
+  public void testGetDetails() {
+    // Create an instance of Employee by adding in temporary values
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    // This will call the getDetails method and store that in a variable called result
+    String result = employee.getDetails();
+    // This will create a string that we expect the getDetails method to return
+    String expected = "The Employee's ID: 1 Name: John Doe Department: Engineering Salary: 50000.0";
+    // This will compare the result of the getDetails method to the expected string
+    assertThat(result).isEqualTo(expected);
+  }
+
+
+  @Test
+  public void testGetId() {
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    int result = employee.getId();
+    assertThat(result).isEqualTo(1);
+  }
+
+  @Test
+  public void testSetId() {
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    employee.setId(2);
+    int result = employee.getId();
+    assertThat(result).isEqualTo(2);
+  }
+
+  @Test
+  public void testGetName() {
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    String result = employee.getName();
+    assertThat(result).isEqualTo("John Doe");
+  }
+
   @Test
-  public void testGetGreeting() {
-    // Act
-    Lesson15.main(null);
+  public void testSetName() {
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    employee.setName("Jane Doe");
+    String result = employee.getName();
+    assertThat(result).isEqualTo("Jane Doe");
   }
+
+  @Test
+  public void testGetDepartment() {
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    String result = employee.getDepartment();
+    assertThat(result).isEqualTo("Engineering");
+  }
+
+  @Test
+  public void testSetDepartment() {
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    employee.setDepartment("Marketing");
+    String result = employee.getDepartment();
+    assertThat(result).isEqualTo("Marketing");
+  }
+
+  @Test
+  public void testGetSalary() {
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    double result = employee.getSalary();
+    assertThat(result).isEqualTo(50000);
+  }
+
+  @Test
+  public void testSetSalary() {
+    Employee employee = new Employee(1, "John Doe", "Engineering", 50000);
+    employee.setSalary(60000);
+    double result = employee.getSalary();
+    assertThat(result).isEqualTo(60000);
+  }
+
+  // -------
+
 }