FluentValidation: Mocking ValidationResult.IsValid - .net-core

Question

I'm using FluentValidation with WebAPI in DotNet core 2. I've written tests for the validator successfully, but now I'm trying to mock the validator for my controller. Controller as follows:
[Route("[controller]")]
public class SecurityController : Controller {
private readonly IValidator<AuthenticateRequest> _authenticateRequestValidator;
public SecurityController(IValidator<AuthenticateRequest> authenticateRequestValidator) {
_authenticateRequestValidator = authenticateRequestValidator;
}
[HttpPost]
[AllowAnonymous]
[Route("auth")]
public async Task<IActionResult> AuthenticateAsync([FromBody] AuthenticateRequest req) {
// Validate
var validator = await _authenticateRequestValidator.ValidateAsync(req);
if(!validator.IsValid) {
return BadRequest();
}
// ...snip
}
}
AuthenticateRequest looks like this:
public class AuthenticateRequest {
public string Username { get; set; }
public string Password { get; set; }
}
And the validator is as follows:
public class AuthenticateRequestValidator : AbstractValidator<AuthenticateRequest> {
/// <summary>
/// Provides a validator for <see cref="AuthenticateRequest" />
/// </summary>
public AuthenticateRequestValidator() {
RuleFor(x => x.Username)
.NotNull()
.NotEmpty()
.WithMessage("Username is required");
RuleFor(x => x.Password)
.NotNull()
.NotEmpty()
.WithMessage("Password is required");
}
}
It's being injected into the controller with dot net core's standard DI. Not posting code as it's not relevant to this issue, as its a testing issue.
I'm testing with xunit, Moq and AutoFixture. Here are two tests:
public class SecurityControllerTests {
private readonly IFixture Fixture = new Fixture().Customize(new AutoMoqCustomization {ConfigureMembers = true});
private readonly Mock<IValidator<AuthenticateRequest>> authenticateRequestValidatorMock;
public SecurityControllerTests() {
authenticateRequestValidatorMock = Mock.Get(Fixture.Create<IValidator<AuthenticateRequest>>());
}
[Fact]
public async Task Authenticate_ValidatesRequest() {
// Arrange
var request = Fixture.Create<AuthenticateRequest>();
authenticateRequestValidatorMock
.Setup(x => x.ValidateAsync(It.Is<AuthenticateRequest>(v => v == request), default(CancellationToken)))
.Returns(() => Fixture.Create<Task<ValidationResult>>())
.Verifiable();
var controller = new SecurityController(authenticationServiceMock.Object, tokenisationServiceMock.Object, authenticateRequestValidatorMock.Object);
// Act
await controller.AuthenticateAsync(request);
// Assert
authenticateRequestValidatorMock.Verify();
}
[Fact]
public async Task Authenticate_Returns400_WhenUsernameValidationFails() {
// Arrange
var request = Fixture.Create<AuthenticateRequest>();
var validationResultMock = new Mock<ValidationResult>();
validationResultMock
.SetupGet(x => x.IsValid)
.Returns(() => true);
authenticateRequestValidatorMock
.Setup(x => x.ValidateAsync(It.Is<AuthenticateRequest>(v => v == request), default(CancellationToken)))
.Returns(() => new Task<ValidationResult>(() => validationResultMock.Object));
var controller = new SecurityController(authenticationServiceMock.Object, tokenisationServiceMock.Object, authenticateRequestValidatorMock.Object);
// Act
var result = await controller.AuthenticateAsync(request);
// Assert
var badRequestResult = Assert.IsType<BadRequestObjectResult>(result);
Assert.IsType<SerializableError>(badRequestResult.Value);
}
}
I need to mock ValidationResult so I can ignore the actual validator logic (which is tested elsewhere) and test the controller logic. There are many other dependencies injected, and much more code, but the pasted code is the crux of the problem and produces the same results when everything else is stripped out.
First test passes, second runs forever when it hits the var validator = await _authenticateRequestValidator.ValidateAsync(req); line in the controller.
Its worth noting that ValidationResult.IsValid is a virtual readonly property.
What is wrong with the second test?

Answer 1

Did you try Asp.Net Core - FluentValidation integration? By this way you dont need to pass Validator depedencies to constructor.
https://github.com/JeremySkinner/FluentValidation/wiki/i.-ASP.NET-Core-integration
FluentValidation fills ModelState in case of validation error and you use it like ;
if (!ModelState.IsValid)
{
return BadRequest(ModelState);
}
For testing it you set ModelState of you Controllers Mock
var controller = new SecurityController(authenticationServiceMock.Object, tokenisationServiceMock.Object, authenticateRequestValidatorMock.Object);
controller.ModelState.AddModelError("test", "test");
// Act
IActionResult actionResult = await controller.AuthenticateAsync(request);
var badRequestObjectResult = actionResult as BadRequestObjectResult;
Assert.NotNull(badRequestObjectResult);
var serializableError = badRequestObjectResult.Value as SerializableError;
// Assert
Assert.NotNull(result);
var badRequestResult = Assert.IsType<BadRequestObjectResult>(result);
var serializableError = assert.IsType<SerializableError>(badRequestResult.Value)
Assert.True(((string[])serializableError["test"])[0] == "test");
Leaving ModelState empty would be enough to ignore the actual validator logic i think.
Also FluentValidation have built-in testing api. You can test your validation logic separately.
https://github.com/JeremySkinner/FluentValidation/wiki/g.-Testing