public void EditCentreDetailsPost_previewSignature_calls_imageResizeService() { // Given const string action = "previewSignature"; var model = new EditCentreDetailsViewModel { BannerText = "Test banner text", CentreSignature = new byte[100], CentreSignatureFile = A.Fake <IFormFile>(), }; var newImage = new byte [200]; A.CallTo(() => imageResizeService.ResizeCentreImage(A <IFormFile> ._)).Returns(newImage); // When var result = controller.EditCentreDetails(model, action); // Then result.Should().BeViewResult(); A.CallTo(() => imageResizeService.ResizeCentreImage(A <IFormFile> ._)).MustHaveHappenedOnceExactly(); var returnModel = (result as ViewResult) !.Model as EditCentreDetailsViewModel; returnModel !.CentreSignature.Should().BeEquivalentTo(newImage); }