Callback not fired for void when Arg.Any passed

[mkolumb]

Describe the bug
I am using the Fluent Assertions for clear assertions but it doesn't affect this bug.

I have interface with the following method

void ReduceProductAvailability(int productId, int orderedQuantity);

When I create the substitute which throws exception for this

var service = Substitute.For<IProductService>();

service
    .When(e => e.ReduceProductAvailability(Arg.Any<int>(), Arg.Any<int>()))
    .Do(x => throw new NotFoundException("XYZ"));

It not throws when in execution I use

service.ReduceProductAvailability(Arg.Any<int>(), Arg.Any<int>())

but it works if I use simple parameters

service.ReduceProductAvailability(0, 0)

To Reproduce
Compare two of the following tests

1. This works

   // Arrange
   
   var service = Substitute.For<IProductService>();
   
   service
       .When(e => e.ReduceProductAvailability(Arg.Any<int>(), Arg.Any<int>()))
       .Do(x => throw new NotFoundException("XYZ"));
   
   // Act
   
   Action result = () => service.ReduceProductAvailability(0, 0);
   
   // Assert
   
   result.Should().Throw<NotFoundException>();

2. This not

   // Arrange
   
   var service = Substitute.For<IProductService>();
   
   service
       .When(e => e.ReduceProductAvailability(Arg.Any<int>(), Arg.Any<int>()))
       .Do(x => throw new NotFoundException("XYZ"));
   
   // Act
   
   Action result = () => service.ReduceProductAvailability(Arg.Any<int>(), Arg.Any<int>());
   
   // Assert
   
   result.Should().Throw<NotFoundException>();

Expected behaviour
It should throws the exception in both cases

Environment:

• NSubstitute version: 3.1.0
• XUnit: 2.4.1
• FluentAssertions: 5.5.0
• Platform: dotnetcore2.1 project on Windows

[tpodolak]

The second examples do not work because you are using argument matcher in a real call.
See documentation . In general Arg matchers should only be used for mock setup and checking received calls. See also feature request nsubstitute/NSubstitute.Analyzers#35 (comment) for NSubstitute.Analyzers with quick description about the proper usage

[mkolumb]

Hi,

You're right.
I checked the documentation, but I didn't find this.
Thank you, I will close this issue.