public async Task AddAssignment_WithValidationMessages_ReturnsValidationMessages()
{
var input = _fixture.Create <AddAssignmentRequest>();
var expectedValidationMessages = _fixture.CreateMany <ValidationMessage>();
_assignmentValidator
.Setup(x => x.ValidateRules(input))
.Returns(expectedValidationMessages);
AddAssignmentResult result = await _sut.AddAssignmentAsync(input);
result.Should().NotBeNull();
result.ValidationMessages.Should().BeEquivalentTo(expectedValidationMessages);
}