public async Task FillEmailBody_Test() { var emailServiceMock = new Mock <IEmailService>().Object; var concreteMailServiceMock = new Mock <IConcreteMailService>().Object; var searchServiceMock = new Mock <ISearchService>().Object; var encodeDecodeServiceMock = new Mock <IEncodeDecodeService>().Object; var emailData = "1 TestGmailId"; string setInvalidEmail = null; var defaultContext = new DefaultHttpContext() { User = new ClaimsPrincipal() }; var controller = new EmailController(emailServiceMock, concreteMailServiceMock, searchServiceMock, encodeDecodeServiceMock) { ControllerContext = new ControllerContext() { HttpContext = defaultContext } }; var result = await controller.FillEmailBody(emailData, setInvalidEmail); Assert.IsInstanceOfType(result, typeof(JsonResult)); }