chore: fixed one of two failing tests

Author: haldanek

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

@@ -34,7 +34,7 @@ private void assertEmployeeInCollection(int id) {
     if (this.employees.containsKey(id)) {
       return;
     }
-    throw new IllegalArgumentException("Employee does not in collection with id " + id);
+    throw new IllegalArgumentException("Employee does not exist in collection with Id " + id);
   }
 
   public int getEmployeeCount() {

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

@@ -50,6 +50,8 @@ void testUpdateEmployee() {
 
   @Test
   void testRemoveEmployee() {
+    // Arrange
+    employeeManager.addEmployee(new Employee(1, "Frankenstein", "Development", 0.0));
     // Act
     employeeManager.removeEmployee(1);
     Employee removedEmployee = employeeManager.getEmployee(1);
@@ -63,7 +65,7 @@ void testAssertEmployeeInCollection() {
     // Arrange & Act & Assert
     assertThatThrownBy(() -> employeeManager.getEmployee(52))
         .isInstanceOf(IllegalArgumentException.class)
-        .hasMessage("Employee does not exist in collection with Id 1");
+        .hasMessage("Employee does not exist in collection with Id 52");
   }
 
   @Test