Make Dummy ValueTuples' members Dummies, to match Tuple

Repreod in 5.2 also.

I got bitten by unexpected behavior with FakeItEasy 2.3.0 (before I updated) while I was doing some ‘refactoring’. I was trying to take advantage of the new tuple language features. Unfortunately I found this not-quite-innocent-as-it-looks change actually broke my tests.

ArmCreatableResourceFactory below is a fake that had no behavior configured for CreateStorageAccountAsync, so it got the default call behavior…

WORKS:

Tuple<StorageAccount, string> storageAccountAndId = await ArmCreatableResourceFactory.CreateStorageAccountAsync(dep, scope, resourceGroup, token, ExecCtx);
storageAccount = storageAccountAndId.Item1;
string storageAccountId = storageAccountAndId.Item2;
var x = storageAccount.AccountName;

DOESN’T WORK:

var (storageAccount, storageAccountId) = await ArmCreatableResourceFactory.CreateStorageAccountAsync(dep, scope, resourceGroup, token, ExecCtx);
var x = storageAccount.AccountName;

The reason it doesn’t work is while the code runs, it results in different state, and when you dereference storageAccount.AccountName, in the second instance it is null!

The main impact of the issue is this kind of brittleness makes the code harder to refactor.

[thomaslevesque]

@blairconrad in this code you’re not using ValueTuple at all, you’re just using tuple deconstruction. var (id, name) = await fake2.Make() is equivalent to this:

Tuple<int, string> tmp =  await fake2.Make();
tmp.Deconstruct(out int id, out string name);

(Deconstruct is an extension method on Tuple<T1, T2>)

@TimLovellSmith I’m not sure I really understand what your problem is. A complete example would help, as well as the answer to this question:

What’s the signature of CreateStorageAccountAsync? Did it change between WORKS and DOESN’T WORK?

If you didn’t change the signature, but only the call site, the problem is probably not related to FakeItEasy.

[blairconrad]

This change has been released as part of FakeItEasy 5.3.0.

Thanks, @TimLovellSmith. Look for your name in the release notes! 🏆