<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Mar 12, 2016 at 1:41 PM, David Hart via swift-evolution <span dir="ltr"><<a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">I am deeply interested in finding solutions for allowing unit-tests of preconditions. Without them, I believe we are leaving many holes in our tests and coverage. The solution found in the Swift project of forking the process seems fairly complicated to implement in XCTest.<br>
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I found a solution online that works by overriding the precondition function with a function that calls a configurable closure which defaults to the original precondition function. It would be great if the Standard Library allowed this by default so that XCTest could use it to offer full support for precondition unit tests.<br>
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<a href="http://stackoverflow.com/a/31349339" rel="noreferrer" target="_blank">http://stackoverflow.com/a/31349339</a><br>
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Is this imaginable?<br></blockquote><div><br></div><div>+1 to this being an important problem to solve, but I'm not sure about the specific solution. Are there performance or security impacts to production code by having this? Could the forked-process solution be implemented once in a framework and then everybody just uses it transparently? The forked-process approach also has the advantage of catching crashes for any other unexpected reason (eg. division by zero), and of ensuring that test executions are hermetically sealed without data leaking between test instances.</div></div></div></div>