function test_DeleteAll()
{
//Arrange
$name = "Math";
$course_number = "112";
$test_course = new course($name, $course_number);
$test_course->save();
$name2 = "The Same Exact Name";
$course_number2 = "112";
$test_course2 = new course($name2, $course_number2);
$test_course2->save();
course::deleteAll();
$result = course::getAll();
$this->assertEquals([], $result);
}
