feat: adds david implentation of Junit Tests for Employee class and EmployeeManager class

Author: Dadenaike251

lesson_15/tdd/tdd_app/src/main/java/com/codedifferently/lesson15/Employee.java

@@ -45,4 +45,15 @@ public double getSalary() {
   public void setSalary(double salary) {
     this.salary = salary;
   }
+
+  public String getDetails() {
+    return "Employee's ID: "
+        + id
+        + " Name: "
+        + name
+        + " Department: "
+        + department
+        + " Salary: "
+        + salary;
+  }
 }

lesson_15/tdd/tdd_app/src/test/java/com/codedifferently/lesson15/EmployeeManagerTest.java

@@ -0,0 +1,97 @@
+package com.codedifferently.lesson15;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+import org.junit.jupiter.api.Test;
+
+public class EmployeeManagerTest {
+  @Test
+  public void test_EmployeeManager() {
+    // Arrange
+    EmployeeManager employeeManager = new EmployeeManager();
+    Employee employee = new Employee(1, "John Doe", "Engineering", 60000);
+
+    // Act
+    employeeManager.addEmployee(employee);
+    Employee retrievedEmployee = employeeManager.getEmployee(1);
+
+    // Assert
+    assertNotNull(retrievedEmployee);
+    assertEquals("John Doe", retrievedEmployee.getName());
+  }
+
+  @Test
+  public void test_addEmployee() {
+    // Arrange
+    EmployeeManager employeeManager = new EmployeeManager();
+    Employee employee = new Employee(2, "Jane Smith", "Marketing", 50000);
+
+    // Act
+    employeeManager.addEmployee(employee);
+
+    // Assert
+    assertEquals(1, employeeManager.getEmployeeCount());
+    assertEquals("Jane Smith", employeeManager.getEmployee(2).getName());
+  }
+
+  @Test
+  public void test_getEmployee() {
+    // Arrange
+    EmployeeManager employeeManager = new EmployeeManager();
+    Employee employee = new Employee(3, "Alice Johnson", "HR", 55000);
+    employeeManager.addEmployee(employee);
+
+    // Act
+    Employee retrievedEmployee = employeeManager.getEmployee(3);
+
+    // Assert
+    assertNotNull(retrievedEmployee);
+    assertEquals("Alice Johnson", retrievedEmployee.getName());
+  }
+
+  @Test
+  public void test_updateEmployee() {
+    // Arrange
+    EmployeeManager employeeManager = new EmployeeManager();
+    Employee employee = new Employee(4, "Bob Brown", "Finance", 70000);
+    employeeManager.addEmployee(employee);
+
+    // Act
+    Employee updatedEmployee = new Employee(4, "Bob Brown", "Finance", 75000);
+    employeeManager.updateEmployee(updatedEmployee);
+
+    // Assert
+    assertEquals(75000, employeeManager.getEmployee(4).getSalary());
+  }
+
+  @Test
+  public void test_removeEmployee() {
+    // Arrange
+    EmployeeManager employeeManager = new EmployeeManager();
+    Employee employee = new Employee(5, "Charlie White", "IT", 65000);
+    employeeManager.addEmployee(employee);
+
+    // Act
+    employeeManager.removeEmployee(5);
+
+    // Assert
+    assertEquals(0, employeeManager.getEmployeeCount());
+  }
+
+  @Test
+  public void test_getEmployeeCount() {
+    // Arrange
+    EmployeeManager employeeManager = new EmployeeManager();
+    Employee employee1 = new Employee(7, "Eve Black", "Sales", 50000);
+    Employee employee2 = new Employee(8, "Frank Blue", "Support", 52000);
+    employeeManager.addEmployee(employee1);
+    employeeManager.addEmployee(employee2);
+
+    // Act
+    int count = employeeManager.getEmployeeCount();
+
+    // Assert
+    assertEquals(2, count);
+  }
+}