feat: created tests with more than 80% code coverage

Author: Cogbonnia

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

@@ -45,4 +45,7 @@ public double getSalary() {
   public void setSalary(double salary) {
     this.salary = salary;
   }
+  public String getDetails() {
+    return "ID: " + id + ", Name: " + name + ", Department: " + department + ", Salary: " + salary;
+  }
 }

lesson_15/tdd/tdd_app/src/test/java/com/codedifferently/lesson15/Lesson15Test.java

@@ -1,19 +1,141 @@
 package com.codedifferently.lesson15;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 import org.junit.jupiter.api.Test;
 
 class Lesson15Test {
 
-  @Test
-  public void testLesson15() {
-    assertThat(new Lesson15()).isNotNull();
-  }
+    @Test
+    public void testLesson15() {
+        assertThat(new Lesson15()).isNotNull();
+    }
 
-  @Test
-  public void testGetGreeting() {
-    // Act
-    Lesson15.main(null);
-  }
+    @Test
+    public void testGetGreeting() {
+        // Act
+        Lesson15.main(null);
+    }
+
+    @Test
+    void testAddEmployee() {
+        // Arrange
+        EmployeeManager manager = new EmployeeManager();
+        Employee employee = new Employee(1, "Jane Doe", "Marketing", 65000.00);
+
+        // Act
+        manager.addEmployee(employee);
+        Employee retrievedEmployee = manager.getEmployee(1);
+
+        // Assert
+        assertThat(retrievedEmployee).isNotNull();
+        assertThat(retrievedEmployee.getName()).isEqualTo("Jane Doe");
+    }
+
+    @Test
+    void testUpdateEmployee() {
+        // Arrange
+        EmployeeManager manager = new EmployeeManager();
+        Employee employee = new Employee(1, "John Doe", "Engineering", 75000.00);
+        manager.addEmployee(employee);
+
+        // Act
+        employee.setName("John Smith");
+        manager.updateEmployee(employee);
+        Employee updatedEmployee = manager.getEmployee(1);
+
+        // Assert
+        assertThat(updatedEmployee.getName()).isEqualTo("John Smith");
+    }
+
+    @Test
+    void testEmployeeCount() {
+        // Arrange
+        EmployeeManager manager = new EmployeeManager();
+        manager.addEmployee(new Employee(1, "John Doe", "Engineering", 75000.00));
+        manager.addEmployee(new Employee(2, "Jane Doe", "Marketing", 65000.00));
+
+        // Act
+        int count = manager.getEmployeeCount();
+
+        // Assert
+        assertThat(count).isEqualTo(2);
+    }
+
+    @Test
+    void testRemoveEmployeeThrowsExceptionWhenNotFound() {
+        // Arrange
+        EmployeeManager manager = new EmployeeManager();
+
+        // Act & Assert
+        assertThatThrownBy(() -> manager.removeEmployee(99))
+            .isInstanceOf(IllegalArgumentException.class)
+            .hasMessageContaining("Employee does not in collection with id 99");
+    }
+
+    @Test
+    void testGetEmployeeThrowsExceptionWhenNotFound() {
+        // Arrange
+        EmployeeManager manager = new EmployeeManager();
+
+        // Act & Assert
+        assertThatThrownBy(() -> manager.getEmployee(99))
+            .isInstanceOf(IllegalArgumentException.class)
+            .hasMessageContaining("Employee does not in collection with id 99");
+    }
+
+    @Test
+    void testUpdateEmployeeThrowsExceptionWhenNotFound() {
+        // Arrange
+        EmployeeManager manager = new EmployeeManager();
+        Employee employee = new Employee(1, "John Doe", "Engineering", 75000.00);
+
+        // Act & Assert
+        assertThatThrownBy(() -> manager.updateEmployee(employee))
+            .isInstanceOf(IllegalArgumentException.class)
+            .hasMessageContaining("Employee does not in collection with id 1");
+    }
+
+    @Test
+    void testEmployeeCreationAndDetails() {
+        // Arrange
+        Employee employee = new Employee(1, "John Doe", "Engineering", 75000.00);
+
+        // Act
+        String details = employee.getDetails();
+
+        // Assert
+        assertThat(details).isEqualTo("ID: 1, Name: John Doe, Department: Engineering, Salary: 75000.0");
+    }
+
+    @Test
+    void testGetters() {
+        // Arrange
+        Employee employee = new Employee(1, "John Doe", "Engineering", 75000.00);
+
+        // Act & Assert
+        assertThat(employee.getId()).isEqualTo(1);
+        assertThat(employee.getName()).isEqualTo("John Doe");
+        assertThat(employee.getDepartment()).isEqualTo("Engineering");
+        assertThat(employee.getSalary()).isEqualTo(75000.00);
+    }
+
+    @Test
+    void testSetters() {
+        // Arrange
+        Employee employee = new Employee(1, "John Doe", "Engineering", 75000.00);
+
+        // Act
+        employee.setId(2);
+        employee.setName("Jane Doe");
+        employee.setDepartment("Marketing");
+        employee.setSalary(65000.00);
+
+        // Assert
+        assertThat(employee.getId()).isEqualTo(2);
+        assertThat(employee.getName()).isEqualTo("Jane Doe");
+        assertThat(employee.getDepartment()).isEqualTo("Marketing");
+        assertThat(employee.getSalary()).isEqualTo(65000.00);
+    }
 }