First tests to listAllCourseMethods
Refactoring the tests and created new tests for listAllCourses() method
Adding tests to getCourseTypes() methods
Refactoring getCourseTypes() method tests
Refactoring deleteCourse() method on Course controller
Refactoring deleteCourseById() method on Course model
Adding tests to deleteCourseFromDb() method on course controller
Refactoring deleteCourseFromDb() method tests