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 49aaabbd..1973591f 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 "Employee: " + id + " " + name + " Department: " + department + " Salary: " + salary;
+  }
 }
diff --git a/lesson_15/tdd/tdd_app/src/test/java/JosephCaballero/EmployeeManagerTest.java b/lesson_15/tdd/tdd_app/src/test/java/JosephCaballero/EmployeeManagerTest.java
new file mode 100644
index 00000000..5008863a
--- /dev/null
+++ b/lesson_15/tdd/tdd_app/src/test/java/JosephCaballero/EmployeeManagerTest.java
@@ -0,0 +1,71 @@
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import com.codedifferently.lesson15.Employee;
+import com.codedifferently.lesson15.EmployeeManager;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class EmployeeManagerTest {
+  EmployeeManager employeeManager;
+  Employee employee;
+  Employee employee2;
+
+  @BeforeEach
+  void setUp() {
+    employeeManager = new EmployeeManager();
+  }
+
+  @Test
+  void testAddEmployee() {
+    employee = new Employee(999, "Joseph", "Boxing", 150000000.5);
+    employeeManager.addEmployee(employee);
+    assertThat(employeeManager.getEmployeeCount()).isEqualTo(1);
+  }
+
+  @Test
+  void testGetEmployee() {
+    employee = new Employee(999, "Joseph", "Boxing", 150000000.5);
+    employeeManager.addEmployee(employee);
+    assertThat(employeeManager.getEmployee(999)).isEqualTo(employee);
+  }
+
+  @Test
+  void testGetEmployee_failedDueToNull() throws RuntimeException {
+    assertThatThrownBy(() -> employeeManager.getEmployee(9))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessage("Employee does not in collection with id 9");
+  }
+
+  @Test
+  void testEmployeeUpdate() {
+    employee = new Employee(999, "Joseph", "Boxing", 150000000.5);
+    employeeManager.addEmployee(employee);
+    employee2 = new Employee(99, "Angelica", "CodeDifferently", 900.55);
+    employeeManager.addEmployee(employee2);
+    employeeManager.updateEmployee(employee2);
+    assertThat(employeeManager.getEmployeeCount()).isEqualTo(2);
+  }
+
+  @Test
+  void testRemoveEmployee() throws RuntimeException {
+    employee = new Employee(999, "Joseph", "Boxing", 150000000.5);
+    employeeManager.addEmployee(employee);
+    employeeManager.removeEmployee(999);
+    assertThat(employeeManager.getEmployeeCount()).isEqualTo(0);
+  }
+
+  @Test
+  void testRemoveEmployee_errorFromNullEmployeeId() throws RuntimeException {
+    assertThatThrownBy(() -> employeeManager.removeEmployee(9))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessage("Employee does not in collection with id 9");
+  }
+
+  @Test
+  void testGetEmployeeCount_whenOneEmployeeIsInTheMap() {
+    employee = new Employee(999, "Joseph", "Boxing", 150000000.5);
+    employeeManager.addEmployee(employee);
+    assertThat(employeeManager.getEmployeeCount()).isEqualTo(1);
+  }
+}
diff --git a/lesson_15/tdd/tdd_app/src/test/java/JosephCaballero/EmployeeTest.java b/lesson_15/tdd/tdd_app/src/test/java/JosephCaballero/EmployeeTest.java
new file mode 100644
index 00000000..6ed0a595
--- /dev/null
+++ b/lesson_15/tdd/tdd_app/src/test/java/JosephCaballero/EmployeeTest.java
@@ -0,0 +1,65 @@
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+
+import com.codedifferently.lesson15.Employee;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+class EmployeeTest {
+
+  Employee employee;
+
+  @BeforeEach
+  void setUp() {
+    employee = new Employee(9, "joseph", "Boxing", 1000000.5);
+  }
+
+  @Test
+  void testGetId() {
+    assertThat(employee.getId()).isEqualTo(9);
+  }
+
+  @Test
+  void testSetId_testingIfNumberOneWorks() {
+    employee.setId(1);
+    assertThat(employee.getId()).isEqualTo(1);
+  }
+
+  @Test
+  void testGetName() {
+    assertThat(employee.getName()).isEqualTo("joseph");
+  }
+
+  @Test
+  void testSetName_testingIfPabloWorks() {
+    employee.setName("Pablo");
+    assertThat(employee.getName()).isEqualTo("Pablo");
+  }
+
+  @Test
+  void testGetDepartment() {
+    assertThat(employee.getDepartment()).isEqualTo("Boxing");
+  }
+
+  @Test
+  void testSetDepartment_testingSettingDepartmentToHome() {
+    employee.setDepartment("Home");
+    assertThat(employee.getDepartment()).isEqualTo("Home");
+  }
+
+  @Test
+  void testGetSalary() {
+    assertThat(employee.getSalary()).isEqualTo(1000000.5);
+  }
+
+  @Test
+  void testSetSalary_salaryToTwoMillionAndFiveCents() {
+    employee.setSalary(2000000.5);
+    assertThat(employee.getSalary()).isEqualTo(2000000.5);
+  }
+
+  @Test
+  void testGetDetails_testsIfWeGetSpecificDetails() {
+    assertThat(employee.getDetails())
+        .isEqualTo("Employee: 9 joseph Department: Boxing Salary: 1000000.5");
+  }
+}