public void BelongsToOthersReturnsCorrectly() { //Arrange long emailId = 1; List <PersonEmails> emails = new List <PersonEmails> { new PersonEmails { EmailId = emailId }, new PersonEmails { EmailId = emailId }, new PersonEmails { EmailId = emailId + 1 }, new PersonEmails { EmailId = emailId + 2 } }; var dbSet = emails.AsQueryable().BuildMockDbSet(); context.Setup(c => c.PersonEmails).Returns(dbSet.Object); IEmailRepository repository = new EmailRepository(context.Object); //Act var result = repository.BelongToOthers(emailId).Result; //Assert Assert.IsInstanceOfType(result, typeof(bool)); Assert.IsTrue(result); }