Arg.Is<object[]> is not working as expected about nsubstitute

[alexandrnikitin]

@IeuanWalker Thank you for raising this.
When NSub compares for equality (e.g. Arg.Is<>()) it relies on the default .NET behavior, meaning that arrays are object and compared by reference not their content.

new object[1].Equals(new object[1]); // false
new object[1] == new object[1]; // false

To make it work you want to provide a lambda to Arg.Is<>() that compares arrays by their content, e.g. using SequenceEqual extension or anything else that works for you.
The following test passes:

    public interface ITest
    {
        int Method(object[] args);
    }

    [Test]
    public void Test()
    {
        var test = Substitute.For<ITest>();
        test.Method(Arg.Is<object[]>(x => x.SequenceEqual(new object[1]))).Returns(2);
        Assert.AreEqual(2, test.Method([1]));
    }

Let us know if you still have questions.

[IeuanWalker]

Thanks all the info, for some reason doing it inline like you have didn't work.
But creating the array variable did work -

object[] jobIdSequence = [jobId];
_db.ReportJobs
	.FindAsync(Arg.Is<object[]>(x => x.SequenceEqual(jobIdSequence)), Arg.Any<CancellationToken>())
	.Returns(new ReportJobTbl
	{
		Id = jobId,
		Job = ReportJobEnum.AddWardToReport,
		HangfireId = 1234
	});