Support for NUnit TestContext.AddFormatter

[jakob-ledermann]

Would it be possible to support NUnits ValueFormatters configured with TestContext.AddFormatter für FsCheck.Nunit tests?

[kurtschelfthout]

Could you give an example of what you’d like to see working, but doesn’t currently?

Also to manage expectations: on FsCheck.NUnit I am happy to take PRs but unlikely to write any new features myself.

[jakob-ledermann]

Thank you for the heads up. Let me explain my problem:
`
sealed class Custom_Type {
public int ID {get;set;}
public string Name {get;set;}

public override string ToString() => "Insufficient Information to identify Data";

}

public void Setup() {
TestContext.AddFormatter(x => $"CustomType: (Id: {((Custom_Type)x).Id}, Name: {((Custom_Type)x).Name})"
}

[Property( ... )]
public Property Sample_with_custom_type(Custom_Type arg) {
Assert.Fail();
}
With the current Versions I see the following message:
Falsifiable, after 1 test (0 shrinks) (StdGen (649505996,296942915)):
Original:
Insufficient Information to identify Data
`

Instead I would prefer to see the following message:
Falsifiable, after 1 test (0 shrinks) (StdGen (649505996,296942915)): Original: CustomType: (Id: {((Custom_Type)x).Id}, Name: {((Custom_Type)x).Name})

If there is a way to achieve the second error message in this case with some configuration for FsCheck.Core I think I can integrate an adapter to the NUnit Custom formatters into FsCheck.NUnit.

[kurtschelfthout]

Yes I think this should be doable - again caveat my knowledge about NUnit is limited - but it seems like that should be a matter of routing FsCheck's output through NUnit's output system somehow: https://github.com/fscheck/FsCheck/blob/master/src/FsCheck.NUnit/FsCheckPropertyAttribute.fs#L25

We do a similar thing for FsCheck.Xunit, which has a ITestOutputHelper we write to.