public void issue_book_does_not_issue_book_to_student() { //given int randomStudentId = rnd.Next(1, TestData.Students.Count); var student = TestData.Students.Where(s => s.StudentId == randomStudentId).First(); int randomBookId = rnd.Next(1, TestData.IssuedBooks.Count); var book = TestData.Books.Where(s => s.BookId == randomBookId).First(); moqStudentService.Setup(m => m.GetStudent(It.IsAny <int>())).Returns(student); moqBookService.Setup(m => m.GetBook(It.IsAny <int>())).Returns(book); var sut = new BookStoreService(moqStudentService.Object, moqBookService.Object, moqBookAllocationService.Object); //when var result = sut.IssueBook(student.StudentId, book.BookId); //then Assert.IsInstanceOfType(result, typeof(bool)); Assert.IsFalse(result); moqStudentService.Verify(v => v.GetStudent(It.IsAny <int>()), Times.Once); moqBookService.Verify(v => v.GetBook(It.IsAny <int>()), Times.Once); }