C#•5mo ago

Trying to learn FluentAssertions, but have a weird result from Should().Be(new Wotsit ())

I'm trying to learn TTD and I wrote a test to compare pseudo-tuple classes after multiplication. The results seem identical, but it counts as a failure. What did I do wrong? My C# ability is decent, but I'm new to TTD and FluentAssertions

7 Replies

TheRainInSpainFalls•5mo ago

hmm... it seems to be an issue with me initialising the variable inside should be. result.Should().BeEquivelentTo(expected); works Urgh! Expected property result.Blue to be 0.04, but found 0.04000000000000001. I really should just use three seperate result.Blue.Should().BeApproximately(0.04, tolerence); I know doubles are slightly inprecise compared to decimals

dreadfullydistinct•4mo ago

You can tell fluentassertions to use different behaviour for doubled

orderDto.Should().BeEquivalentTo(order, options => options 
    .Using<DateTime>(ctx => ctx.Subject.Should().BeCloseTo(ctx.Expectation, 1.Seconds()))
    .WhenTypeIs<DateTime>());

orderDto.Should().BeEquivalentTo(order, options => options 
    .Using<DateTime>(ctx => ctx.Subject.Should().BeCloseTo(ctx.Expectation, 1.Seconds()))
    .WhenTypeIs<DateTime>());

dreadfullydistinct•4mo ago

From https://fluentassertions.com/objectgraphs/

Fluent Assertions

Object graph comparison

TheRainInSpainFalls•4mo ago

Thank you, I'll check it when I wake up.

dreadfullydistinct•4mo ago

And you could also apply that globally using the static AssertionOptions But I can’t quite remember the syntax for that

TheRainInSpainFalls•4mo ago

That'll be worth trying, non-decimals/ints rarely match perfectly.

dreadfullydistinct•4mo ago

Yeah, I mainly use it with time, when I’m asserting against the creation date of something returned from my api. Obviously it is approximately DateTime.UtcNow but +- how long the request took So I allow 1 second of tolerance

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Trying to learn FluentAssertions, but have a weird result from Should().Be(new Wotsit ())