sinon.sandbox analog?

[vovacodes]

Some test runners, e.g. ava, can execute your tests in parallel. Having a single "mocking" context might lead to race conditions when doing td.reset(). Is there a way of creating an isolated mocking context that could be restored independently of the other tests, like sinon.sandbox provides?

[searls]

There is not, but if you consider what sinon.sandbox does and what td.reset applies to, I'm not sure there's much daylight for an additional feature to exist.

Sandbox is a really odd feature, that I think is more intended to (1) scope global sinon configuration down, and (2) give some way of resetting more than one double at a time (I don't believe there is a global sinon.reset, which was the major reason I'd see anyone using the sandbox feature at all.

In fact, take a look here for why sandbox doesn't actually solve the problem you suggest it would: avajs/ava#1066 -- as long as you're globally replacing something, you can't run tests concurrently safely, full stop.

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So instead what I'd suggest is to either (1) mark your unit tests that use td.js to replace production-side code as .serial, or (2) avoid using td.replace at all for async tests and instead use traditional/manual dependency injection to get your fakes to your subject.

Fears of running serial as undercutting the value of ava are, I believe, unfounded if you're using td.js to write isolated unit tests. Since that means they're not doing any I/O, running them concurrently intra-process doesn't buy you much. Each file is still tested concurrently by ava in a separate process, but intra-file specs would be run serially for your isolated unit tests. And that advice applies to both Sinon & td.js

[searls]

I wrote more about this last year here: #131 (comment)