public void TeacherControllerAssignExamToGroupTest()
{
//Arrange
bool isExamAssigned = false;
var group = new Mock <Group>("Test");
group.Setup(t => t.AssignExam(It.IsAny <Exam>())).Callback(() => isExamAssigned = true);
Teacher teacher = new Teacher("Petro", "Petrov", "ID", "petrov");
TeacherController teacherController = new TeacherController(teacher);
Exam exam = new Exam("SomeExam", 1, 3, 1);
//Act
teacherController.AssignExamToGroup(exam, group.Object);
//Assert
Assert.IsTrue(isExamAssigned);
}